AC Tonnage Calculator (sqft OR BTU input)

1 ton = 12,000 BTU/hr cooling. Convert sqft → tons (rule-of-thumb sizing) OR BTU → tons (direct).

Inputs

500-650 typical for US residential.

Read from equipment nameplate or Manual-J result.

Result

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General calculation reads

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How to use this calculator

  • Enter total floor area to cool.
  • Adjust ft²/ton if you know your local norm (cooler climates: 700+; hotter: 500).

About this calculator

AC capacity is measured in tons (1 ton = 12,000 BTU/hr cooling, named after melting that much ice in 24h). Sizing rule of thumb: 1 ton per 500-650 ft² for typical US homes. For precise sizing in extreme climates or homes with unusual loads, a Manual J calculation is required.

Frequently asked

Why round to ½ ton?+
AC equipment comes in 0.5-ton increments. A 2.7-ton calculation usually rounds to a 3-ton unit.
Underize or oversize?+
Slight oversize is OK for cooling capacity, but causes short-cycling and poor humidity control. Right-sized via Manual J is best.
Heat pump tons?+
Same metric — 1 ton = 12,000 BTU/hr cooling capacity. Heating capacity varies by outdoor temp.
Mini-split vs central tonnage?+
Same. A 2-ton mini-split = 2-ton central (24,000 BTU/hr). Per-zone is more efficient.
SEER affects sizing?+
SEER measures efficiency (BTU/Wh), not capacity. Higher SEER = same BTU at less electricity.

Related calculators

BTU for Room Cooling Calculator
BTU/hr needed = ft² × climate factor (20-30 BTU/ft² for typical US climates).
Furnace Size Calculator
Furnace BTU = ft² × climate-zone factor (30-60 BTU/ft²).
BTU for Room Heating Calculator
Heating BTU/hr = ft² × insulation factor × ΔT.
Heat Load Calculator (U-value method)
Heat loss = U × area × ΔT for each surface, summed.
Ductwork CFM Calculator
CFM (cubic feet per minute) = BTU/hr × 0.07. Used for sizing ducts.
kWh Cost Per Month
Cost = W × hr/day × 30 / 1000 × $/kWh.

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