BTU to Tons Converter
Convert cooling capacity between BTU per hour and tons of refrigeration. Enter a value and pick the direction (BTU/hr to tons, or tons to BTU/hr) to get the equivalent in tons, BTU per hour, and kilowatts.
Example: with Convert BTU/hr → tons · Cooling capacity 24000 → Converted capacity: 2.000 tons.
- In kilowatts7.034 kW
- Rough coverageAbout 2.0 tons — roughly 1,000 sq ft of cooling (rule of thumb ~1 ton per 400–600 sq ft)
Computed by the calculator below using its default values. Change any input to see your own numbers.
One ton of refrigeration = 12,000 BTU/hr = 3.517 kW. The unit comes from the heat needed to melt one ton of ice in 24 hours — a genuinely old benchmark still used to size air conditioners.
Where the ton of cooling comes from
A ton of refrigeration is not a weight — it is a rate of heat removal. It was defined as the cooling you get from melting one short ton (2,000 lb) of ice over 24 hours. Working through the latent heat of fusion lands on 12,000 BTU per hour, and that number stuck as the standard unit for air conditioner and chiller capacity.
So converting is simple division: BTU per hour divided by 12,000 gives tons, and tons times 12,000 gives BTU per hour. A 24,000 BTU/hr system is a 2-ton unit; a 60,000 BTU/hr system is 5 tons.
Reading the number for sizing
Kilowatts offer a second view of the same capacity: one ton equals about 3.517 kW of heat removal. That is handy when comparing equipment rated in metric units or estimating electrical load, though the electrical draw of the compressor depends on efficiency, not just cooling output.
A common rule of thumb puts one ton at roughly 400 to 600 square feet of living space, but climate, insulation, windows, and ceiling height all shift that. Use it to sanity-check a quote, then rely on a proper load calculation for the final size.
How it’s calculated
1 ton of refrigeration = 12,000 BTU/hr exactly (by definition). Tons = BTU/hr ÷ 12,000; BTU/hr = tons × 12,000. Kilowatts use 1 kW = 3,412.14163 BTU/hr, so 1 ton = 3.51685 kW. Coverage estimates use a rule-of-thumb 500 sq ft per ton.
The square-footage figure is a rough rule of thumb, not a load calculation. Proper sizing (Manual J) accounts for climate, insulation, windows, orientation, and occupancy.
BTU/hr, tons, and kilowatts
| BTU/hr | Tons | Kilowatts |
|---|---|---|
| 6,000 | 0.5 | 1.76 kW |
| 12,000 | 1.0 | 3.52 kW |
| 18,000 | 1.5 | 5.28 kW |
| 24,000 | 2.0 | 7.03 kW |
| 36,000 | 3.0 | 10.55 kW |
| 60,000 | 5.0 | 17.58 kW |
Computed with 1 ton = 12,000 BTU/hr = 3.51685 kW.
Common mistakes
- Confusing tons of cooling with tons of weight — they measure heat removal, not mass.
- Mixing BTU (energy) with BTU/hr (power); air conditioners are rated in BTU per hour.
- Sizing purely by square footage and skipping insulation, windows, and climate.
- Assuming kilowatts of cooling equals the unit's electrical draw — efficiency sets the power bill.
Frequently asked questions
How do I convert BTU to tons?
Divide BTU per hour by 12,000. For example, 24,000 BTU/hr ÷ 12,000 = 2 tons. To go the other way, multiply tons by 12,000 to get BTU per hour.
How many BTU is a 1-ton AC unit?
Exactly 12,000 BTU per hour. A 2-ton unit is 24,000 BTU/hr and a 3-ton unit is 36,000 BTU/hr, since capacity scales directly with tonnage.
How many kilowatts is one ton of cooling?
About 3.517 kW of heat removal, since 12,000 BTU/hr equals 3,412.14 BTU/hr per kilowatt times 3.517. That is the cooling output, not the compressor's electrical draw.
How many square feet does a ton of AC cool?
As a rough rule of thumb, roughly 400 to 600 square feet per ton. Actual coverage depends heavily on insulation, windows, ceiling height, and climate, so treat it as a starting estimate.
Why is cooling measured in tons at all?
The unit dates to ice cooling: one ton of refrigeration equals the heat needed to melt a ton of ice in a day, which works out to 12,000 BTU per hour.