SettingsSettings for this calculationUS
The rated heating or cooling capacity, in the unit chosen below.
Take it from the data sheet or the nameplate: the capacity the machine is rated to move, not the electrical power it draws. A heat pump can carry different heating and cooling ratings, and a rating holds at the test conditions printed with it, so enter the one for the duty you are comparing.
The unit of the figure above; the result gives the other two, and the watts.
Tons and BTU/h are how US catalogues, load calculations and permits state capacity; kilowatts are how UK, European and Australian data sheets state it. A figure in watts is a thousandth of the kilowatt figure, so enter it as kilowatts. BTU/h and kilowatts are answered in tons.
Which unit the headline gives a tonnage in; the breakdown shows both either way.
BTU/h is the unit the ton is defined in and the one a US load calculation ends in; kilowatts are what a metric data sheet or a heat loss report states. The two answers are the same capacity.
Converted capacity
36,000 BTU/h
Converted by definition: one ton of refrigeration is exactly 12,000 BTU/h, and one BTU/h is 0.29307107 W, from the International Table Btu.
- In refrigeration tons
- 3 refrigeration tons
- In BTU per hour (BTU/h)
- 36,000 BTU/h
- In kilowatts (kW)
- 10.55 kW
- In watts (W)
- 10,550.56 W
They open the calculator with your figures already in it
Refrigeration Tons, BTU/h and kW Converter: 36,000 BTU/h — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B.8: British thermal unit (International Table) per hour to watt, 2.930 711 E−01; ton of refrigeration (12 000 Btu_IT/h) to watt, 3.516 853 E+03; ton, short (2000 lb), the mass unit, to kilogram 9.071 847 E+02
- NIST Special Publication 811, footnotes: the Fifth International Conference on the Properties of Steam (London, 1956) defined the International Table calorie as 4.1868 J, so the International Table Btu is exactly 1.055 055 852 62 kJ; the thermochemical Btu rests on the thermochemical calorie of exactly 4.184 J
Inputs used
- Capacity to Convert
- 3
- Converting From
- Refrigeration tons
- Show a Tonnage In
- BTU per hour (BTU/h)
Intermediate steps
- In refrigeration tons
- 3 refrigeration tons
- In BTU per hour (BTU/h)
- 36,000 BTU/h
- In kilowatts (kW)
- 10.55 kW
- In watts (W)
- 10,550.56 W
Confidence note: Converted by definition: one ton of refrigeration is exactly 12,000 BTU/h, and one BTU/h is 0.29307107 W, from the International Table Btu.
What this calculation does not cover
- The arithmetic restates a capacity; it does not measure one. A rating holds at the indoor and outdoor conditions it was tested at, and a heat pump's or air conditioner's real output moves as those change, falling in heating as the outdoor air gets colder.
- These are heat-moving capacities, not electrical loads. A heat pump delivering 3.5 kW (about 12,000 BTU/h) of heat or cooling draws a fraction of that from the supply, so neither the tons nor the kilowatts here size a circuit, a breaker or a generator.
- The ton here is the ton of refrigeration, a rate of heat flow of 12,000 BTU/h, defined from melting a short ton of ice, 2,000 lb (907 kg), in a day. It is not a mass, and it never adds to the tons the same site uses for gravel and stone.
- A size quoted as a round number of tons is a sales label rather than a measurement. Convert the certified capacity on the data sheet, and compare two machines only at the same rating conditions.
Add the equipment this sizes
This result is a specification — 36,000 BTU/h — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-10-05 · v1.0.0
Regulatory standards & verification citations2
- NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B.8: British thermal unit (International Table) per hour to watt, 2.930 711 E−01; ton of refrigeration (12 000 Btu_IT/h) to watt, 3.516 853 E+03; ton, short (2000 lb), the mass unit, to kilogram 9.071 847 E+02
- NIST Special Publication 811, footnotes: the Fifth International Conference on the Properties of Steam (London, 1956) defined the International Table calorie as 4.1868 J, so the International Table Btu is exactly 1.055 055 852 62 kJ; the thermochemical Btu rests on the thermochemical calorie of exactly 4.184 J
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A tonnage is a capacity, not a weight: one ton of refrigeration moves heat at 12,000 BTU/h, which is 3.517 kW. US catalogues size air conditioners and heat pumps in tons, so this is the conversion that sets a US machine's nameplate beside a heat loss worked in BTU/h or a UK or Australian data sheet written in kilowatts.