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Heat Loss BTU Calculator

Calculate heat loss per room of your home to choose the right size and style radiators.

We have comprehensive BTU (British Thermal Unit) calculators here on our website, offering both basic and advanced programs to determine the heating requirements for your space. Discover the importance of this crucial step before investing in radiators and make informed decisions tailored to your space.

Both our basic and advanced calculators are available online for convenient use. The advanced program, STARS for short, requires a login for access, allowing you to manage and duplicate previous projects effortlessly. Please use the advanced version of the programme at

Calculating BTU for radiators is a crucial step in guaranteeing your room is adequately heated. Larger rooms demand more substantial radiators or a higher quantity, while compact radiators suffice for smaller spaces. Our calculators simplify this process, providing accurate estimates based on Delta-T 50°C (Δ-T50°C) in accordance with BS EN 442 standards.

Your use of the Stelrad basic heat loss calculator is subject to these terms and conditions.

STARS – Advanced Heat Loss Programme

STARS offers a comprehensive approach to calculating heating requirements. Inputting detailed room specifications, including dimensions, materials, and insulation levels, yields instant heat loss calculations. STARS suggests suitable radiators and even extends to calculating heating needs for entire buildings, recommending appropriate boilers.

Users can print or save radiator schedules and boiler specifications for reference.

How to Calculate BTU for a Room

For accurate BTU calculations:

  1. Measure room dimensions (length, width, height) in meters.
  2. Use the BTU formula: BTU = (cubic meters) x (insulation level factor) x (temperature difference factor).
  3. Choose radiators with BTU ratings matching or exceeding calculated values.

Working Out BTU for Radiators

Determining BTU for radiators involves considering room features, insulation, and desired temperature. Our BTU calculator simplifies this complex task, providing insights into the most suitable radiators for each room based on comprehensive factors.

Enhance the accuracy of your heat loss calculations with our advanced heat loss program. Save the link for quick access to this invaluable tool today.

Heat Loss Prevention Calculate Heat Loss More Accurately

How Many BTU to Heat a Room?

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The number of BTUs needed to heat a room depends on various factors. Our BTU calculator guides you through room details, ensuring precise recommendations for efficient heating.

What is the Best Setting for Central Heating?

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Set your thermostat between 18°C and 21°C for optimal comfort, as recommended by the Energy Saving Trust[1]. Adjust the temperature to your preferences, knowing our calculators help maintain a cosy environment with the right radiators in each room.



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