Example 1 — Standard room
- Volume: 50 m³
- Heat demand: 40 W/m³
Heating power: 2000 W
That is about 2.00 kW
This is a straightforward example of moving from volume to an approximate heating power value.
Heating power
Estimate room heating power from room volume and unit heat demand in W/m³.
This calculator gives a fast, approximate heating power result based on room volume and an assumed W/m³ demand value. It is useful for first comparisons, but it does not replace a full heat-loss calculation. Related: room volume, insulation requirement.
Results
Enter data and click Calculate.
How the results are calculated
power (W) = room volume (m³) × heat demand (W/m³). kW = W ÷ 1000. Room type and window area are optional refinements and are not applied when left empty.
How to use this calculator
- Enter the room volume in m³.
- If the form includes additional options such as building standard or other support parameters, set them according to your calculation assumptions.
- Enter the unit heat demand in W/m³ if the calculator requires that value directly.
- Read the result in watts or kilowatts and treat it as a quick approximate estimate.
Example scenarios
Example 2 — Larger living room in a better-insulated standard
- Volume: 84 m³
- Heat demand: 35 W/m³
Heating power: 2940 W
That is about 2.94 kW
A lower W/m³ demand can offset a larger room volume if the building standard is better.
Example 3 — Small room with higher demand
- Volume: 27.3 m³
- Heat demand: 45 W/m³
Heating power: 1228.5 W
That is about 1.23 kW
A smaller room does not always mean very low heating power if the assumed demand value is higher.
FAQ
What does W/m³ mean?
It is an approximate heat demand value for each cubic metre of room volume. The higher the number, the more power is needed for the same room size.
Does this calculator provide an exact heating system selection?
No. It is a fast approximate tool, not a full detailed heat-loss calculation.
Where should I get the W/m³ value from?
Most often from simplified assumptions based on building type, insulation quality, and thermal standard. If you have design data, use that instead of guessing.
Does room volume matter a lot?
Yes. Even with the same floor area, two rooms with different heights may need different heating power.
Is it better to show the result in W or kW?
The most practical option is both. Watts are useful for calculation, while kilowatts are easier to compare with heating devices.
What most often makes the result too low?
Using a W/m³ value that is too optimistic or ignoring the real thermal condition of the building.
Is this calculator suitable for one room and for a whole house?
Yes, as a quick support tool. However, for larger systems, precise design calculations are much more complex.
Which calculator is related to this one?
Most naturally room volume, and in a broader context also insulation and building geometry tools.