BTU Calculator for Indoor Heaters

How many BTUs do you need to heat your work area or room? Use this handy BTU calculator to choose the best size space heater or electric fireplace stove for your needs!

Room Size (in feet):

Temperature Increase Needed:


A note about starting temperature: In order to calculate BTUs, we need to determine how much the temperature needs to increase to reach the desired temperature. Since space heaters are intended as a supplemental heat source, they will normally only need to raise the room temperature a few degrees.

On the other hand, a heater intended to be the primary heat source will need to be able to raise the room temperature higher than the outdoor temperature, which will require more BTUs.