How many BTU per square foot for heating?

Heating & HVACACCA Manual J Principles

HVAC Heat Load Calculator (Manual J Estimate)

Estimate whole-home heating BTU/hr and cooling tonnage requirements based on square footage, climate zone, and building insulation.

Heating & HVAC Field StandardsACCA Manual J Principles

Engineering formulations calibrated to IPC, UPC & NEC specificationsSub-Zero Cold Climate Tolerances

Quick Summary & Key Answer

A 2,000 sq ft home in a cold northern climate (Zone 5-7) requires approximately 80,000 to 110,000 BTU/hr of heating capacity and 2.5 to 3.0 tons of cooling. In sub-arctic Alaska (Zone 8), heating demand increases to 115,000 to 135,000 BTU/hr due to extreme sub-zero design temperatures.

1 Ton of HVAC cooling = 12,000 BTU/hr.
Oversized furnaces cycle rapidly, causing temperature swings and premature heat exchanger cracking.
Manual J calculates heat loss through walls, windows, ceilings, and infiltration.

Interactive Calculator

Adjust inputs for real-time results

Conditioned Floor Areasq ft

sq ft

Average Ceiling Heightfeet

feet

Climate Zone (Heating Demand)

Building Insulation Quality

Calculated OutputHVAC Sized

Recommended Heating Capacity

94,500 BTU/hrBTU/hr

Recommended Furnace / Boiler Size: 95k BTU Output
Recommended AC / Heat Pump Cooling: 2.5 Tons (30,000 BTU)
Design Heat Load per Square Foot: 47.3 BTU/sq ft

Note: In cold climates like Anchorage, Alaska, heating capacity must handle extreme design temperatures of -15°F to -25°F.

Why Manual J Sizing Matters

Oversizing heating equipment wastes fuel and causes uncomfortable drafts; undersizing leaves homes cold during cold snaps.

Frequently Asked Questions

Common questions regarding this calculation and code compliance

Standard heating sizing ranges from 30 BTU/sq ft in mild southern climates to 55-65 BTU/sq ft in sub-zero northern regions.