About the Refrigeration Tons to BTU Converter
This tons to BTU converter translates air-conditioner and heat-pump tonnage into BTU per hour, kilowatts and watts, and works in reverse when you start from a BTU or kW rating. A “ton” in HVAC is not a weight: it is a rate of cooling equal to 12,000 BTU per hour, the heat needed to melt one short ton of ice in 24 hours.
Use it to compare a 3-ton central AC quote with a 36,000 BTU mini-split, to read European equipment rated in kW, or to translate a load calculation into the nominal tonnage contractors talk about. Residential systems usually come in half-ton steps from 1.5 to 5 tons.
Tonnage is cooling output, not electricity used. Enter the unit’s EER (BTU/h of cooling per watt of electricity) to estimate the electrical power it draws at full load; leave it at 0 to skip that estimate.
With the default inputs, the btu per hour is 36,000 BTU/h. Change any value above to recalculate instantly.
How to use the refrigeration tons to btu converter
- 1Enter the capacity from the nameplate, quote or load calculation.
- 2Choose whether that number is in tons, BTU/h, kW or watts.
- 3Optionally enter the EER from the spec sheet to estimate electrical draw.
- 4Read BTU/h, tons and kW, and compare with the standard sizes in the chart.
Formula and method
One ton of refrigeration is defined as exactly 12,000 BTU per hour (288,000 BTU per day), originally the cooling effect of melting a short ton (2,000 lb) of ice over 24 hours. Multiplying tons by 12,000 gives BTU/h; dividing BTU/h by 12,000 gives tons.
To reach watts, the calculator uses the International Table BTU of 1,055.05585262 joules, so 1 BTU/h = 0.29307107 W and 1 ton = 3.5169 kW. The optional electrical estimate divides cooling output by the energy efficiency ratio (EER), which is the BTU/h of cooling delivered per watt drawn at a standard test condition; real draw varies with outdoor temperature.
- tons
- Refrigeration tons (12,000 BTU/h each)
- BTU/h
- British thermal units per hour of heat removed
- kW
- Kilowatts of cooling capacity
- EER
- Energy efficiency ratio, BTU/h per watt of electricity
Worked examples
3-ton central air conditioner
3 tons × 12,000 = 36,000 BTU/h. Multiplying by 0.29307 W per BTU/h gives 10.55 kW of cooling. With an EER of 12 the compressor and fans draw about 36,000 ÷ 12 = 3,000 W.
24,000 BTU mini-split in tons
24,000 ÷ 12,000 = 2 tons, which is 7.03 kW of cooling. No EER was entered, so the electrical estimate is left at 0.
5 kW European heat pump
5,000 W ÷ 0.29307 W per BTU/h = 17,061 BTU/h, or 17,061 ÷ 12,000 = 1.42 tons — between a 1-ton and 1.5-ton US unit.
Frequently asked questions
How many BTU is a ton of AC?+
One ton of air conditioning equals exactly 12,000 BTU per hour. So a 2-ton unit is 24,000 BTU/h, a 3-ton unit 36,000 BTU/h and a 5-ton unit 60,000 BTU/h.
Why is AC capacity measured in tons?+
Before mechanical refrigeration, buildings were cooled with ice. A ton of cooling is the heat absorbed by melting one short ton (2,000 lb) of ice over 24 hours, about 288,000 BTU per day or 12,000 BTU per hour.
How many kW is a 1 ton air conditioner?+
One refrigeration ton is about 3.517 kW of cooling output. That is not the electricity it uses; a typical unit with an EER of 10–13 draws roughly 0.9–1.2 kW per ton.
What size AC do I need per square foot?+
Rules of thumb of around 400–600 square feet per ton are common, but climate, insulation, windows and ceiling height change the answer a lot. A Manual J load calculation is the reliable way to size a system.
Is a refrigeration ton the same as a metric tonne?+
No. A refrigeration ton is a unit of power (12,000 BTU/h), not mass. It has nothing to do with the weight of the equipment. A rarely used Japanese or "metric" refrigeration ton (about 3.86 kW) exists, but HVAC ratings almost always mean the 12,000 BTU/h ton.