BTU for Room Heating Calculator
Heating BTU/hr = ft² × insulation factor × ΔT.
Result
BTU/hr needed
37,500
10.99 kW heat output.
- Area250 ft²
- Insulation factor3 BTU/ft²/°F
- ΔT50°F
- BTU/hr37,500
- kW equivalent10.99
Step-by-step
- BTU/hr = 250 × 3 × 50 = 37,500.
How to use this calculator
- Enter room area.
- Pick insulation level.
- Enter the design ΔT (typical: 50-70°F).
About this calculator
Heating load depends on three factors: room size, how well-insulated the room is, and how cold it gets outside. ΔT (delta temperature) is the design indoor temp minus the design outdoor low. Standard US design temps: 70°F inside, climate-zone-dependent low (-10°F to 30°F). For whole-home systems, use a Manual J calculation.
Frequently asked
Indoor: 70°F. Outdoor "design temp": 99% winter — see ASHRAE tables. Atlanta: 22°F → ΔT 48. Chicago: -2°F → ΔT 72. Minneapolis: -16°F → ΔT 86.
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