Ensure your room stays warm efficiently with our Heater Size Calculator. By factoring in room dimensions, insulation quality, and your local climate zone, we estimate the heating power (in Watts and BTUs) needed to maintain a comfortable temperature.
Privacy Protected
Calculate Heater Size & Wattage
Calculate the required heater size in Watts and BTUs based on room size and climate. Fast, free, and 100% private. All processing happens locally.
Share Tool
About Calculate Heater Size & Wattage
1
Room Size
Enter length, width, and ceiling height.
2
Climate & Insulation
Select your climate zone and insulation quality.
3
Result
View the recommended Watts and BTUs for your space.
Key Features
Wattage & BTU Output
Get results in both Watts (for electric heaters) and BTUs (for gas/other).
Climate Adjustment
Adapts calculations for Warm, Moderate, or Cold climate zones.
Insulation Factor
Accounts for heat loss based on insulation quality.
Frequently Asked Questions
A general rule is 10 watts per square foot, but this varies significantly with climate and insulation. Our calculator provides a more precise estimate.
Watts measure electrical power, while BTUs measure heat energy. 1 Watt is approximately equal to 3.41 BTUs.
Yes, a larger heater will heat the room faster and cycle off. However, a massively oversized heater might cause temperature swings and waste energy.
Related Tools
View allLast updated on