{"id":27283,"date":"2026-09-11T11:00:54","date_gmt":"2026-09-11T11:00:54","guid":{"rendered":"https:\/\/www.turnbull.co.uk\/cms\/?p=27283"},"modified":"2026-09-11T11:13:29","modified_gmt":"2026-09-11T11:13:29","slug":"btu-calculator-for-radiators","status":"publish","type":"post","link":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/","title":{"rendered":"What Radiator Size Do I Need? BTU Calculator and Size Guide"},"content":{"rendered":"<div class=\"wpb-content-wrapper\" id=\"wpb-content-root\"><p>[vc_row][vc_column][vc_column_text]<\/p>\n<h2 style=\"text-align: center;\">Choosing a new radiator for your home isn&#8217;t just about picking a design that looks great on your wall.<\/h2>\n<p style=\"text-align: center;\">The single most important factor when selecting a radiator is making sure it delivers the right amount of heat to keep your room warm and comfortable without wasting energy.<br \/>\nIf you are wondering what size radiator you need or how to convert BTU to watts, this guide breaks down everything you need to know about your heating system.<\/p>\n<p style=\"text-align: center;\">Estimated reading time: 3.5 minutes<br \/>\nPhoto by Ksenia Chernaya on Pexels<\/p>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_separator border_width=&#8221;2px&#8221; accent_color=&#8221;#F7BE68&#8243;][\/vc_column][\/vc_row][vc_row][vc_column width=&#8221;1\/2&#8243; css=&#8221;.vc_custom_1740481318304{background-color: #C2C2C200 !important;}&#8221;][vc_single_image image=&#8221;27339&#8243; add_caption=&#8221;yes&#8221; img_size=&#8221;400&#215;400&#8243; alignment=&#8221;center&#8221;][\/vc_column][vc_column width=&#8221;1\/2&#8243; css=&#8221;.vc_custom_1740481293684{border-color: #C2C2C200 !important;}&#8221;][vc_column_text]<\/p>\n<h2>Why BTU Matters When Selecting a Radiator<\/h2>\n<p>BTU stands for British Thermal Unit. It measures the heat energy required to raise the temperature of one pound of water by one degree Fahrenheit. The BTU rating tells you how much heat output a radiator produces per hour to offset overall heat loss.<\/p>\n<p>Getting your heat output calculation right ensures:<\/p>\n<ul>\n<li><strong>Comfort:<\/strong> No cold spots during freezing winter months.<\/li>\n<li><strong>Energy Efficiency:<\/strong> An undersized radiator works continuously without reaching the target room temperature, while an oversized radiator can waste energy.<\/li>\n<li><strong>Lower Fuel Bills:<\/strong> Balanced heating keeps boiler and heat pump systems working in their sweet spot.<\/li>\n<\/ul>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_separator style=&#8221;dotted&#8221; border_width=&#8221;2px&#8221; accent_color=&#8221;#F7BE68&#8243;][\/vc_column][\/vc_row][vc_row][vc_column width=&#8221;1\/2&#8243;][vc_column_text]<\/p>\n<h2>How to Calculate BTU for a Room: Step-by-Step<\/h2>\n<p>To calculate the required BTU rating for a room, follow this straightforward process:[\/vc_column_text][vc_column_text]<\/p>\n<h3>1. Measure the Room Volume<\/h3>\n<p>Calculate the total volume using your room dimensions <strong>in cubic feet:<\/strong><\/p>\n<p><strong>Length (ft) \u00d7 Width (ft) \u00d7 Height (ft) = Total Volume (cu ft)<\/strong>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/2&#8243;][vc_single_image image=&#8221;27299&#8243; img_size=&#8221;large&#8221; alignment=&#8221;center&#8221;][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n<h3>2. Apply the Base Heating Factor<\/h3>\n<p>Multiply the total volume by the base factor for your specific room type. Higher factors account for rooms where occupants sit still or exposed spaces prone to draughts:[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column width=&#8221;1\/3&#8243;][vc_single_image image=&#8221;27309&#8243; img_size=&#8221;300&#215;300&#8243; alignment=&#8221;center&#8221;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>Storage Rooms, Walk-In Closets and Kitchens<br \/>\nFactor 3<\/strong><\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Storage rooms need minimal background heat to prevent dampness and frost.<br \/>\nKitchens require a lower base output because appliances generate ambient heat.<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/3&#8243;][vc_single_image image=&#8221;27308&#8243; img_size=&#8221;300&#215;300&#8243; alignment=&#8221;center&#8221;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>Bedrooms<br \/>\nFactor 4<\/strong><\/p>\n<p>[\/vc_column_text][vc_empty_space height=&#8221;6px&#8221;][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Aimed at a target room temperature of 18\u00b0C (64\u00b0F) for comfortable sleeping.<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/3&#8243;][vc_single_image image=&#8221;27311&#8243; img_size=&#8221;300&#215;300&#8243; alignment=&#8221;center&#8221;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>Living Rooms, Dining Rooms and Home Offices<br \/>\nFactor 5<\/strong><\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Target room temperature around 21\u00b0C (70\u00b0F) where occupants are seated and inactive.<\/p>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column width=&#8221;1\/3&#8243;][vc_single_image image=&#8221;27306&#8243; img_size=&#8221;300&#215;300&#8243; alignment=&#8221;center&#8221;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>Hallways, Corridors and Landings<br \/>\nFactor 5<\/strong><\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Requires higher heat to counter frequent draughts from front doors and open staircases.<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/3&#8243;][vc_single_image image=&#8221;27305&#8243; img_size=&#8221;300&#215;300&#8243; alignment=&#8221;center&#8221;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>Bathrooms and En-Suites<br \/>\nFactor 6<\/strong><\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Target room temperature around 22\u201323\u00b0C (72\u201373\u00b0F) for maximum comfort when stepping out of the shower or bath.<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/3&#8243;][vc_single_image image=&#8221;27304&#8243; img_size=&#8221;300&#215;300&#8243; alignment=&#8221;center&#8221;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>Conservatories and Sunrooms<br \/>\nFactor 6 to 7<\/strong><\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Large glass areas lose heat rapidly, requiring maximum output.<\/p>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n<h3>3. Adjust for Room Insulation &amp; Features<\/h3>\n<p>Adjust your baseline estimate based on room conditions that impact heat loss:[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>Double Glazed Windows<\/strong><\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>Single Glazed Windows<\/strong><\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>External Walls<\/strong><\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>North-Facing Rooms<\/strong><\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><strong>Poor Insulation<\/strong><\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><b data-path-to-node=\"0\" data-index-in-node=\"0\">French Doors or Large Glass Areas<\/b><\/p>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column width=&#8221;1\/6&#8243;][vc_single_image image=&#8221;27321&#8243; alignment=&#8221;center&#8221;][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_single_image image=&#8221;27320&#8243; img_size=&#8221;small&#8221; alignment=&#8221;center&#8221;][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_single_image image=&#8221;27320&#8243; img_size=&#8221;small&#8221; alignment=&#8221;center&#8221;][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_single_image image=&#8221;27320&#8243; img_size=&#8221;small&#8221; alignment=&#8221;center&#8221;][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_single_image image=&#8221;27319&#8243; img_size=&#8221;small&#8221; alignment=&#8221;center&#8221;][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_single_image image=&#8221;27318&#8243; img_size=&#8221;small&#8221; alignment=&#8221;center&#8221;][\/vc_column][\/vc_row][vc_row][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Standard double glazed windows are already factored into the base calculations, so no adjustment (0%) is needed.<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Add 10% for every single-glazed window, as single glass loses significantly more heat.<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Add 10% for every exterior-facing wall.<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Add 10% for colder sun exposure.<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Add 15% if the room lacks cavity wall insulation, solid brick walls, or has less than 100mm loft insulation.<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/6&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: center;\">Add 15\u201320% to cover extra heat loss through large glass panels and frame seals.<\/p>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row gap=&#8221;0px&#8221; css_animation=&#8221;none&#8221; css=&#8221;.vc_custom_1788960277040{background-color: #DCDCDC !important;}&#8221;][vc_column][vc_column_text]<\/p>\n<h2 style=\"text-align: center; color: #000e77;\">The Complete BTU Formula at a Glance<\/h2>\n<p style=\"text-align: center; color: #000e77;\">Putting Steps 1 through 3 all together gives you the complete equation for calculating any room&#8217;s heating requirements:<\/p>\n<p style=\"text-align: center; color: #000e77;\"><strong>(Length ft\u00a0 x\u00a0 width ft\u00a0 x\u00a0 height ft)\u00a0 x\u00a0 Room Base Factor\u00a0 +\u00a0 Feature Adjustments (%)\u00a0 =\u00a0 BTU Output<\/strong><\/p>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n<p style=\"text-align: center;\" data-path-to-node=\"5\">For example, a small bedroom measuring 10ft \u00d7 10ft \u00d7 8ft, with one single-glazed window and one external wall, and good roof insulation:<\/p>\n<p style=\"text-align: center;\" data-path-to-node=\"6,0,0\"><strong>Calculate Volume:<\/strong> 10ft \u00d7 10ft \u00d7 8ft = 800 cu ft<\/p>\n<p style=\"text-align: center;\" data-path-to-node=\"6,1,0\"><strong>Apply Base Factor:<\/strong> 800 cu ft \u00d7 4 (Bedroom Factor) = 3,200 BTU baseline<\/p>\n<p style=\"text-align: center;\" data-path-to-node=\"6,2,0\"><strong>Add Feature Adjustments:<\/strong> 3,200 BTU + 20% (for window and external wall) = 3,840 BTU<\/p>\n<p style=\"text-align: center;\" data-path-to-node=\"7,0,0\"><strong>Final Heating Requirement:<\/strong> 3,840 BTU (or approx. 1,125 Watts)<\/p>\n<p>[\/vc_column_text][vc_separator style=&#8221;dotted&#8221; border_width=&#8221;2&#8243; color=&#8221;orange&#8221;][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n<h2>Quick Radiator BTU Chart<\/h2>\n<p>Need a quick baseline before adding adjustments for windows, walls, and insulation?<\/p>\n<p>Use the table below to estimate the required amount of heat.[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column width=&#8221;1\/3&#8243;][vc_column_text]Room Type[\/vc_column_text][vc_separator border_width=&#8221;1px&#8221; accent_color=&#8221;#D6D5D5&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: left;\">Small bathroom<\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: left;\">Small bedroom<\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: left;\">Medium bedroom<\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: left;\">Small Living Room<\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: left;\">Large Living Room<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/3&#8243;][vc_column_text]Average room dimensions (ft)[\/vc_column_text][vc_separator border_width=&#8221;1px&#8221; accent_color=&#8221;#D6D5D5&#8243;][vc_column_text]<\/p>\n<p style=\"text-align: left;\">10 x 10 x 8<\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: left;\">10 x 10 x 8<\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: left;\">12 x 12 x 8<\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: left;\">12 x 14 x 8<\/p>\n<p>[\/vc_column_text][vc_column_text]<\/p>\n<p style=\"text-align: left;\">15 x 20 x 8<\/p>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/3&#8243;][vc_column_text]Estimated BTU Rating needed[\/vc_column_text][vc_separator border_width=&#8221;1px&#8221; accent_color=&#8221;#D6D5D5&#8243;][vc_column_text]2,400[\/vc_column_text][vc_column_text]3,200[\/vc_column_text][vc_column_text]4,608[\/vc_column_text][vc_column_text]7,840[\/vc_column_text][vc_column_text]12,000[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_separator style=&#8221;dotted&#8221; border_width=&#8221;2&#8243; color=&#8221;orange&#8221;][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n<p style=\"text-align: center;\"><em>Disclaimer: The formulas, estimations, and BTU charts provided in this article serve as a general guide for estimation purposes only. Environmental factors, boiler flow temperatures, and specific building construction details can alter heating demands and affect the heating the room requires.<\/em><\/p>\n<p style=\"text-align: center;\"><em>Always consult a qualified heating engineer or plumbing professional before purchasing or installing new heating equipment to confirm exact room and heating requirements.<\/em><\/p>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_separator style=&#8221;dotted&#8221; border_width=&#8221;2&#8243; color=&#8221;orange&#8221;][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n<h2 style=\"text-align: left;\">Frequently Asked Questions<\/h2>\n<h3 style=\"color: #000000; text-align: left;\">How to Convert BTU to Watts?<\/h3>\n<p style=\"color: #000000; text-align: left;\">Converting between the two units is straightforward:<\/p>\n<p style=\"color: #000000; text-align: left;\"><strong>BTU to Watts:<\/strong> Divide BTU by 3.412<br \/>\n<em>(Example: 4,000 BTU \u00f7 3.412 = 1,172 Watts)<\/em><\/p>\n<p style=\"color: #000000; text-align: left;\"><strong>Watts to BTU:<\/strong> Multiply Watts by 3.412<br \/>\n<em>(Example: 1,500 Watts \u00d7 3.412 = 5,118 BTU)<\/em><\/p>\n<h3 style=\"text-align: left;\">Can I install two smaller radiators instead of one large one?<\/h3>\n<p style=\"text-align: left;\">Yes. In large or long rooms, splitting your required BTU total between two smaller radiators often provides much better distribution for the overall amount of heat than installing one single high-output radiator.<\/p>\n<h3 style=\"text-align: left;\">What happens if I buy an oversized radiator?<\/h3>\n<p style=\"text-align: left;\">Installing a slightly larger radiator than strictly necessary is generally fine if you fit a Thermostatic Radiator Valve (TRV) to maintain your desired room temperature. The TRV automatically reduces hot water flow once the room reaches your set temperature.<\/p>\n<h3 style=\"text-align: left;\">Do heat pumps require different BTU calculations?<\/h3>\n<p style=\"text-align: left;\">Heat pumps run at lower flow temperatures than gas boilers. When selecting a radiator for a heat pump heating system, you need larger radiators (or higher Delta 30 ratings) to deliver the same warmth to the room and overcome natural heat loss, even in well-insulated rooms with double glazed windows.<\/p>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_separator style=&#8221;dotted&#8221; border_width=&#8221;2px&#8221; accent_color=&#8221;#F7BE68&#8243;][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n<h2>Related Blogs<\/h2>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row gap=&#8221;0px&#8221; css_animation=&#8221;none&#8221; css=&#8221;.vc_custom_1789051482610{background-color: #DCDCDC !important;}&#8221;][vc_column width=&#8221;1\/3&#8243;][vc_single_image image=&#8221;27372&#8243; img_size=&#8221;400&#215;300&#8243; alignment=&#8221;center&#8221;][vc_column_text]<\/p>\n<h3 style=\"text-align: center;\"><a href=\"https:\/\/www.turnbull.co.uk\/cms\/information\/how-to-fit-a-thermostatic-radiator-valve\/\">How Do I Fit A Thermostatic Radiator Valve?<\/a><\/h3>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/3&#8243;][vc_single_image image=&#8221;27389&#8243; img_size=&#8221;400&#215;300&#8243; alignment=&#8221;center&#8221;][vc_column_text]<\/p>\n<h3 style=\"text-align: center;\"><a href=\"https:\/\/www.turnbull.co.uk\/cms\/information\/how-to-bleed-a-radiator\/\">How To Bleed A Radiator<\/a><\/h3>\n<p>[\/vc_column_text][\/vc_column][vc_column width=&#8221;1\/3&#8243;][vc_single_image image=&#8221;26040&#8243; img_size=&#8221;400&#215;300&#8243; alignment=&#8221;center&#8221;][vc_column_text]<\/p>\n<h3 style=\"text-align: center;\"><a href=\"https:\/\/www.turnbull.co.uk\/cms\/information\/prevent-frozen-pipes-this-winter\/\">Prevent Frozen Pipes This Winter<\/a><\/h3>\n<p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_separator border_width=&#8221;2px&#8221; accent_color=&#8221;#F7BE68&#8243;][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]<\/p>\n<h2 style=\"text-align: center; color: #000e77;\"><b data-path-to-node=\"1,3,0\" data-index-in-node=\"0\">Planning your next plumbing and heating project?<\/b><\/h2>\n<p style=\"text-align: center; color: #000e77;\">Browse our online range of radiators and valves to get reliable warmth delivered to your door<\/p>\n<p>[\/vc_column_text][vc_btn title=&#8221;Shop Radiators and Valves&#8221; align=&#8221;center&#8221; custom_background=&#8221;#FF9900&#8243; custom_text=&#8221;#fff&#8221; gradient_color_1=&#8221;turquoise&#8221; gradient_color_2=&#8221;blue&#8221; link=&#8221;url:https%3A%2F%2Fwww.turnbull.co.uk%2Fcategory%2Fplumbing-and-heating%2Fradiators-valves|title:Extra&#8221; custom_hover_background=&#8221;#f5b14b&#8221; custom_hover_text=&#8221;#f7f7f7&#8243; custom_border=&#8221;#FF9900&#8243; custom_hover_border=&#8221;#f5b14b&#8221;][\/vc_column][\/vc_row][vc_row][vc_column][vc_separator border_width=&#8221;2px&#8221; accent_color=&#8221;#F7BE68&#8243;][\/vc_column][\/vc_row]<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Calculate the radiator size and heat output your space requires using a straightforward BTU formula based on room dimensions, usage, and insulation<\/p>\n","protected":false},"author":12,"featured_media":27332,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[85,14],"tags":[251,19,20,252,24],"class_list":["post-27283","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-advice-tips","category-plumbing","tag-btu-calculator","tag-heating","tag-plumbing","tag-plumbing-and-heating","tag-radiators"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.3 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>BTU Calculator: Calculate Radiator &amp; Heating Size Fast<\/title>\n<meta name=\"description\" content=\"Use our BTU calculator to find the radiator size and heat output you need. Calculate required BTUs or Watts for any room in a few quick steps.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"BTU Calculator: Calculate Radiator &amp; Heating Size Fast\" \/>\n<meta property=\"og:description\" content=\"Use our BTU calculator to find the radiator size and heat output you need. Calculate required BTUs or Watts for any room in a few quick steps.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/\" \/>\n<meta property=\"og:site_name\" content=\"Turnbull &amp; Co Limited\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/TurnbullBuildersMerchant\/\" \/>\n<meta property=\"article:published_time\" content=\"2026-09-11T11:00:54+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-09-11T11:13:29+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.turnbull.co.uk\/cms\/app\/uploads\/2026\/09\/white-radiator-ksenia-chernaya-pexels.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"939\" \/>\n\t<meta property=\"og:image:height\" content=\"528\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Emma Bryant\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@turnbullcoltd\" \/>\n<meta name=\"twitter:site\" content=\"@turnbullcoltd\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Emma Bryant\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"6 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/\"},\"author\":{\"name\":\"Emma Bryant\",\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/#\\\/schema\\\/person\\\/b8b2cc6d5eb8a1b3bf6b9d83da2a9303\"},\"headline\":\"What Radiator Size Do I Need? BTU Calculator and Size Guide\",\"datePublished\":\"2026-09-11T11:00:54+00:00\",\"dateModified\":\"2026-09-11T11:13:29+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/\"},\"wordCount\":1986,\"publisher\":{\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/#organization\"},\"image\":{\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/app\\\/uploads\\\/2026\\\/09\\\/white-radiator-ksenia-chernaya-pexels.jpg\",\"keywords\":[\"btu calculator\",\"heating\",\"plumbing\",\"plumbing and heating\",\"radiators\"],\"articleSection\":[\"Advice &amp; Tips\",\"Plumbing\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/\",\"url\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/\",\"name\":\"BTU Calculator: Calculate Radiator & Heating Size Fast\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/app\\\/uploads\\\/2026\\\/09\\\/white-radiator-ksenia-chernaya-pexels.jpg\",\"datePublished\":\"2026-09-11T11:00:54+00:00\",\"dateModified\":\"2026-09-11T11:13:29+00:00\",\"description\":\"Use our BTU calculator to find the radiator size and heat output you need. Calculate required BTUs or Watts for any room in a few quick steps.\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/#primaryimage\",\"url\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/app\\\/uploads\\\/2026\\\/09\\\/white-radiator-ksenia-chernaya-pexels.jpg\",\"contentUrl\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/app\\\/uploads\\\/2026\\\/09\\\/white-radiator-ksenia-chernaya-pexels.jpg\",\"width\":939,\"height\":528},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/information\\\/btu-calculator-for-radiators\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"What Radiator Size Do I Need? BTU Calculator and Size Guide\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/#website\",\"url\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/\",\"name\":\"Turnbull &amp; Co Limited\",\"description\":\"Building, Plumbing and Heating Supplies\",\"publisher\":{\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/#organization\",\"name\":\"Turnbull & Compnay\",\"url\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/#\\\/schema\\\/logo\\\/image\\\/\",\"url\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/app\\\/uploads\\\/revslider\\\/turnbull-logo_blue-outline_without-tagline.png\",\"contentUrl\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/app\\\/uploads\\\/revslider\\\/turnbull-logo_blue-outline_without-tagline.png\",\"width\":2608,\"height\":538,\"caption\":\"Turnbull & Compnay\"},\"image\":{\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/#\\\/schema\\\/logo\\\/image\\\/\"},\"sameAs\":[\"https:\\\/\\\/www.facebook.com\\\/TurnbullBuildersMerchant\\\/\",\"https:\\\/\\\/x.com\\\/turnbullcoltd\",\"https:\\\/\\\/www.instagram.com\\\/turnbullkitchensbathrooms\\\/\"]},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/www.turnbull.co.uk\\\/cms\\\/#\\\/schema\\\/person\\\/b8b2cc6d5eb8a1b3bf6b9d83da2a9303\",\"name\":\"Emma Bryant\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/bb7cb7be1c8b3a108354aef7cb908b9dae5d5af73616d07c52bf6d6c9f2e306f?s=96&d=mm&r=g\",\"url\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/bb7cb7be1c8b3a108354aef7cb908b9dae5d5af73616d07c52bf6d6c9f2e306f?s=96&d=mm&r=g\",\"contentUrl\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/bb7cb7be1c8b3a108354aef7cb908b9dae5d5af73616d07c52bf6d6c9f2e306f?s=96&d=mm&r=g\",\"caption\":\"Emma Bryant\"}}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"BTU Calculator: Calculate Radiator & Heating Size Fast","description":"Use our BTU calculator to find the radiator size and heat output you need. Calculate required BTUs or Watts for any room in a few quick steps.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/","og_locale":"en_US","og_type":"article","og_title":"BTU Calculator: Calculate Radiator & Heating Size Fast","og_description":"Use our BTU calculator to find the radiator size and heat output you need. Calculate required BTUs or Watts for any room in a few quick steps.","og_url":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/","og_site_name":"Turnbull &amp; Co Limited","article_publisher":"https:\/\/www.facebook.com\/TurnbullBuildersMerchant\/","article_published_time":"2026-09-11T11:00:54+00:00","article_modified_time":"2026-09-11T11:13:29+00:00","og_image":[{"width":939,"height":528,"url":"https:\/\/www.turnbull.co.uk\/cms\/app\/uploads\/2026\/09\/white-radiator-ksenia-chernaya-pexels.jpg","type":"image\/jpeg"}],"author":"Emma Bryant","twitter_card":"summary_large_image","twitter_creator":"@turnbullcoltd","twitter_site":"@turnbullcoltd","twitter_misc":{"Written by":"Emma Bryant","Est. reading time":"6 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/#article","isPartOf":{"@id":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/"},"author":{"name":"Emma Bryant","@id":"https:\/\/www.turnbull.co.uk\/cms\/#\/schema\/person\/b8b2cc6d5eb8a1b3bf6b9d83da2a9303"},"headline":"What Radiator Size Do I Need? BTU Calculator and Size Guide","datePublished":"2026-09-11T11:00:54+00:00","dateModified":"2026-09-11T11:13:29+00:00","mainEntityOfPage":{"@id":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/"},"wordCount":1986,"publisher":{"@id":"https:\/\/www.turnbull.co.uk\/cms\/#organization"},"image":{"@id":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/#primaryimage"},"thumbnailUrl":"https:\/\/www.turnbull.co.uk\/cms\/app\/uploads\/2026\/09\/white-radiator-ksenia-chernaya-pexels.jpg","keywords":["btu calculator","heating","plumbing","plumbing and heating","radiators"],"articleSection":["Advice &amp; Tips","Plumbing"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/","url":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/","name":"BTU Calculator: Calculate Radiator & Heating Size Fast","isPartOf":{"@id":"https:\/\/www.turnbull.co.uk\/cms\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/#primaryimage"},"image":{"@id":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/#primaryimage"},"thumbnailUrl":"https:\/\/www.turnbull.co.uk\/cms\/app\/uploads\/2026\/09\/white-radiator-ksenia-chernaya-pexels.jpg","datePublished":"2026-09-11T11:00:54+00:00","dateModified":"2026-09-11T11:13:29+00:00","description":"Use our BTU calculator to find the radiator size and heat output you need. Calculate required BTUs or Watts for any room in a few quick steps.","breadcrumb":{"@id":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/#primaryimage","url":"https:\/\/www.turnbull.co.uk\/cms\/app\/uploads\/2026\/09\/white-radiator-ksenia-chernaya-pexels.jpg","contentUrl":"https:\/\/www.turnbull.co.uk\/cms\/app\/uploads\/2026\/09\/white-radiator-ksenia-chernaya-pexels.jpg","width":939,"height":528},{"@type":"BreadcrumbList","@id":"https:\/\/www.turnbull.co.uk\/cms\/information\/btu-calculator-for-radiators\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.turnbull.co.uk\/cms\/"},{"@type":"ListItem","position":2,"name":"What Radiator Size Do I Need? BTU Calculator and Size Guide"}]},{"@type":"WebSite","@id":"https:\/\/www.turnbull.co.uk\/cms\/#website","url":"https:\/\/www.turnbull.co.uk\/cms\/","name":"Turnbull &amp; Co Limited","description":"Building, Plumbing and Heating Supplies","publisher":{"@id":"https:\/\/www.turnbull.co.uk\/cms\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.turnbull.co.uk\/cms\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.turnbull.co.uk\/cms\/#organization","name":"Turnbull & Compnay","url":"https:\/\/www.turnbull.co.uk\/cms\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.turnbull.co.uk\/cms\/#\/schema\/logo\/image\/","url":"https:\/\/www.turnbull.co.uk\/cms\/app\/uploads\/revslider\/turnbull-logo_blue-outline_without-tagline.png","contentUrl":"https:\/\/www.turnbull.co.uk\/cms\/app\/uploads\/revslider\/turnbull-logo_blue-outline_without-tagline.png","width":2608,"height":538,"caption":"Turnbull & Compnay"},"image":{"@id":"https:\/\/www.turnbull.co.uk\/cms\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/TurnbullBuildersMerchant\/","https:\/\/x.com\/turnbullcoltd","https:\/\/www.instagram.com\/turnbullkitchensbathrooms\/"]},{"@type":"Person","@id":"https:\/\/www.turnbull.co.uk\/cms\/#\/schema\/person\/b8b2cc6d5eb8a1b3bf6b9d83da2a9303","name":"Emma Bryant","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/secure.gravatar.com\/avatar\/bb7cb7be1c8b3a108354aef7cb908b9dae5d5af73616d07c52bf6d6c9f2e306f?s=96&d=mm&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/bb7cb7be1c8b3a108354aef7cb908b9dae5d5af73616d07c52bf6d6c9f2e306f?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/bb7cb7be1c8b3a108354aef7cb908b9dae5d5af73616d07c52bf6d6c9f2e306f?s=96&d=mm&r=g","caption":"Emma Bryant"}}]}},"_links":{"self":[{"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/posts\/27283","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/comments?post=27283"}],"version-history":[{"count":44,"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/posts\/27283\/revisions"}],"predecessor-version":[{"id":27403,"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/posts\/27283\/revisions\/27403"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/media\/27332"}],"wp:attachment":[{"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/media?parent=27283"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/categories?post=27283"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.turnbull.co.uk\/cms\/wp-json\/wp\/v2\/tags?post=27283"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}