Heater size: watts per m² explained

Choosing the right heater wattage per square meter is crucial for efficient heating without wasting energy or risking overheating. This guide explains how to calculate the necessary watts based on your room size.

Heater calculator

HVAC
Recommended heater size
— W
Rule of thumb
Base 30–50 W/m³ scaled by insulation and climate.
Rough sizing only; always check manufacturer specs. See Disclaimer.

How the estimate works

Heaters are rated in watts, indicating their power output and heat generation capacity. To determine the appropriate heater size for a given space, you need to know the area of the room in square meters (m²). A common rule is to use 50-100 watts per m² as a starting point, but this can vary depending on insulation quality and desired temperature increase. For instance, a poorly insulated room might require more watts to maintain warmth compared to an adequately insulated one.

How to reduce the cost

FAQ

The average ranges from 50 to 100 watts per square meter, depending on room insulation and desired warmth level.

Using a heater with more power than necessary can lead to overheating and increased energy costs. Stick to the calculated requirement for efficiency.

Divide the space into simpler shapes, calculate their areas separately, then sum them up to get the total area before selecting a heater.

For a general-purpose tool, see: /appliance-electricity-cost-calculator