Find out how much heat your radiator produces with our BTU calculator. Enter room size and details to estimate radiator output and cost. Metric & imperial units.
Enter your measurements above to see the results.
First, calculate the room volume (length × width × height, in m or ft). Multiply by the room type factor and insulation factor to get kW needed. Convert kW to BTU/h (1 kW = 3412 BTU/h). The cost is required kW × price per kW.
Suppose you select Metric, a lounge of 4m x 3.5m x 2.4m, average insulation (1.0), room type lounge (1.5), and price per kW is 50 GBP. Room volume = 4 × 3.5 × 2.4 = 33.6 m³. Required kW = 33.6 × 1.5 × 1.0 / 30 = 1.68 kW. Required BTU = 1.68 × 3412 = 5731 BTU/h. Estimated cost = 1.68 × 50 = 84 GBP.
Radiator heat output depends on your room's size, type, and insulation. The calculation involves multiplying the room’s volume by adjustment factors for room use and insulation, then converting the result to BTUs or kW for easy comparison.
BTU (British Thermal Unit) and kW (kilowatts) are standard measures of heat output. Knowing the required BTU or kW ensures your radiator can adequately heat your space, making your home comfortable and energy efficient.
Selecting a radiator with the correct output not only keeps your room warm but can also save on energy bills. Oversized radiators waste energy, while undersized ones won’t provide enough heat. This calculator helps you strike the right balance.
Radiator prices vary by output and type. By entering your local currency and typical price per kW, you can estimate the cost of a suitable radiator, helping you budget for your heating upgrade.
Whether you measure rooms in metres or feet, this calculator supports both metric and imperial systems. Select your preferred unit system to see results in m³, kW, and BTU/h or the imperial equivalents.
A radiator’s heat output depends on its size, design, and the temperature of the water inside. Typical radiators produce between 500 and 3000 BTU/h (0.15–0.88 kW), but you should calculate the exact requirement for your room using a BTU calculator.
A standard single-panel radiator of average size (e.g., 600mm x 1000mm) typically produces around 2000–2500 BTU/h (0.6–0.7 kW), but output varies by manufacturer and model. Always check the product specifications.
Yes, radiators are an efficient and reliable source of heat for most homes. They provide even, controllable warmth and can be sized to suit any room using a BTU calculator.
You calculate radiator heat output by assessing the room’s volume, adjusting for room type and insulation, and converting the result to BTU/h or kW. Our calculator simplifies this process for you.
Home radiators typically operate with surface temperatures between 60–75°C (140–167°F) when heating. The exact temperature depends on your heating system’s settings and the radiator type.
