HVAC Tonnage Converter
Convert between BTU per hour, tons of cooling, and kilowatts for HVAC and air conditioning systems.
Type in any field and the others update.
Type in any field — the others update instantly.
HVAC cooling capacity is measured in BTU/hr, tons, and kW.
Conversion factors:
- 1 ton of cooling = 12,000 BTU/hr = 3.517 kW
- 1 kW = 3,412 BTU/hr = 0.2843 tons
- 1 BTU/hr = 0.000293 kW
Common residential AC sizes:
- 1.5 ton = 18,000 BTU/hr = 5.28 kW (small room)
- 2 ton = 24,000 BTU/hr = 7.03 kW (medium room)
- 3 ton = 36,000 BTU/hr = 10.55 kW (large room)
- 4 ton = 48,000 BTU/hr = 14.07 kW (small house)
- 5 ton = 60,000 BTU/hr = 17.58 kW (large house)
Rough sizing guide:
- About 1 ton per 500-600 sq ft of living space.
- Climate, insulation, and windows affect actual needs.
The “ton” in air conditioning has nothing to do with weight. It dates from the days of ice cooling: one ton of cooling is the rate of heat needed to melt one ton of ice in 24 hours, which works out to 12,000 BTU per hour. The unit stuck long after ice gave way to compressors.
Sizing is where this matters, and bigger is not better. An oversized AC cools the air quickly, then shuts off before it has run long enough to pull moisture out, leaving the room cold but clammy while the unit short-cycles, wears faster, and wastes energy. An undersized one runs constantly and never quite catches up on a hot day. The rough “1 ton per 500 to 600 square feet” guide is only a starting point; a proper sizing (a Manual J load calculation) accounts for insulation, windows, ceiling height, and climate, which can easily shift the answer by a full ton.
How we build and check this converter
This converter runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.