Heat Loss Calculator

Find heat loss through a building component.

Surface area

U-value (BTU/h·ft²·°F)

Temperature difference (°F)

Heat loss (BTU/h) 2,400

Formula: heat loss = U-value × area × ΔT

Step-by-step with your numbers:

1. Values used:

2. Surface area = 200

3. U-value = 0.3 BTU/h·ft²·°F

4. Temperature difference = 40 °F

6. Heat loss = Surface area x U-value x Temperature difference = 200 x 0.3 x 40 = 2,400BTU/h

Did we solve your problem today?

Find how much heat escapes through a wall, window or roof component.

The math behind it

heat loss = U-value × surface area × temperature difference. Lower U-value = better insulation.

200 ft² wall, U 0.3, ΔT 40°F → 2,400 BTU/h.

U-value vs R-value?

U = 1 ÷ R-value. A higher R-value means lower U and less heat loss.