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AC Size Calculator

Estimate central AC size in BTU/hr and tons from floor area and climate.

Inputs

Inputs and assumptions

Conditioned floor area. (1 sq ft = 0.093 sq m).

20 mild, 25 average, 30 hot climate.

Sunny/poor insulation: 1.1 to 1.15. Shaded/new: 0.9.

Result

Cooling needed (BTU/hr)
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AC size (tons)
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What to check

  • Conditioned floor area
  • Climate zone and insulation level

Related calculators

Rule-of-thumb screening estimate, not an ACCA Manual J calculation. Confirm with a room-by-room Manual J load calculation and installer quotes before buying equipment.

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