Heating Power Calculator
Estimate a room's heating power need (kW) from volume and insulation level. Helps size a heater.
1.75 kW
Heating power need
| Volume | 50.0 m³ |
| Power need | 1.75 kW |
| In watts | 1,750 W |
The heating power calculator helps you estimate how much power your room needs to stay warm. Enter the area, ceiling height and insulation level, and you get the power need in kilowatts to guide your heater sizing.
How the calculator works and what it’s for▾
How the power need is calculated
The calculator first works out the room volume by multiplying the area by the ceiling height. It then multiplies that volume by a power factor based on the insulation level, which reflects heat loss per cubic metre.
As a rough guideline, the power need is around 25–50 watts per cubic metre: a well-insulated space needs less, a poorly insulated one needs more.
What you enter and what you get
You enter the room area in square metres, the ceiling height in metres and the insulation level. The insulation level drives the power factor used in the calculation.
The result shows the room volume in cubic metres and the power need both in kilowatts and in watts, making it easier to choose a heater.
Who it is for
The calculator suits a rough sizing of an electric heater, an infrared panel or a heat pump at home, at a cabin or in a storage space.
It gives a quick order of magnitude when you want to know whether the device you are considering is enough to heat the room.
Good to know about accuracy
The result is an indicative estimate, not exact sizing. The real power need is affected by factors such as the number of windows, air leaks, orientation and the local climate.
For precise sizing you need a building-specific heat-loss calculation that accounts for these factors in detail.
🔄 Reviewed June 2026
Frequently asked questions
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