Calculate Your Heater Size

Use this calculator to quickly estimate the heating requirements for a single room. Please be aware that calculating heat loss is complex, and there are many variables that can affect the final result.

Calculate Your Heater Size

Use this calculator to quickly estimate the heating requirements for a single room. Please be aware that calculating heat loss is complex, and there are many variables that can affect the final result.

Save Your Estimate to Email

Enter your email to receive your room specs, recommended wattage and radiator configuration.

Room Details

Enter the length and width of your room in metres, or click Enter Room Area Manually to enter the total area of your room in square metres.

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M2
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Windows

Tell us about your windows and glass doors. Choose from the size dropdown or manually enter the window area for the most accurate calculation.

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M2

External Walls & Doors

You can enter the number of external walls in your room, or enter the total length of your external walls for a more accurate calculation.

What is an external wall?

External walls are any that connect to the outside or a cold space such as a garage. If you share a wall with a neighbour, this does not count as an external wall.

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M

Enter the total number of standard external doors (if any). If you have glass sliding doors, include these in your window measurements instead.

Room Insulation

Select which description best describes the insulation in your room for each interior surface. If you know the exact insulation value (often found in home energy efficiency reports), enter it into the column on the right.

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Or
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Or

Need to heat several rooms or an entire building?

Use our personalised 3-step online estimate

Our expert estimators will run the numbers and calculate your precise heating needs.

Then, our heating consultant will ensure your quoted solution perfectly fits each room's unique layout.

Start A Detailed Estimate

Will take up to 7 mins+