Written by Maud
Edited on
20 July 2026
·
10:41
How do you choose the power of an electric heater?
The power of an electric heater indicates how powerful the heater is and how much energy it consumes. How much wattage you need depends on the room. Take a look at the size of the room and how well it's insulated. In this article, you can read how much power suits your situation. This way, you can choose the right heater for your space.
Electric heater power
The power of an electric heater shows how powerful it is. A 2000W heater heats a larger room better than a 1000W model. We calculate how much square meter the heater heats based on the power. We also take the insulation of the room into account. For a badly insulated space, you need more power than for a well-insulated room. This way, you can choose a heater that suits your situation.
Difference in power per insulation level
Poor insulation: 50W per cubic meter
Was your house built before 1975, does it have single-paned glass, thin layers of insulation, or a cat flap that opens often? We consider this poor insulation. In such a space, the heater needs 50W to heat 1m3. Do you have a 1000W heater? You can heat 20m3 in this case. This means you need more power in rooms where heat disappears quickly.
Good insulation: 35W per cubic meter
Do you live in a newly-built house or in a house with thick insulation, double-paned glass, and not many crevices? You have good insulation. In such a room, the heater needs 35W per cubic meter. With a 100W heater, you can heat about 28.5m3. This means you need less power, because the heat stays in better.
Calculate the power for your room
Do you want to know how much power your heater needs? First, calculate how big your room is: length x width x height = number of cubic meters.
Example: 6m x 5m x 2.5m = 75m3.
After that, take a look at your house. Is it well-insulated? Multiply this with 35W. Is it badly insulated? Use 50W.
Example for bad insulation: 75 x 50W = 3750W. This means you need 3750W total heater power. Most electric heaters go up to 2500W, so in this example you need at least 2.
Article by Maud
Heater Expert.
