BTU to Tons of Refrigeration Converter
Enter a cooling capacity in BTU per hour, tons of refrigeration (RT), watts, or kilowatts and every other unit updates instantly. One refrigeration ton equals 12,000 BTU/hr, the heat needed to melt one short ton of ice in 24 hours. Use this converter to size HVAC systems, match chiller specs, or compare equipment ratings across unit systems.
What is a ton of refrigeration?
A ton of refrigeration (RT) is a unit of cooling power defined as the heat required to melt one short ton (2,000 lb) of ice at 32 F (0 C) over 24 hours. Working that out: one pound of ice absorbs 144 BTU when melting, so 2,000 lb absorbs 288,000 BTU over 24 hours, giving 288,000 / 24 = 12,000 BTU/hr. That is the internationally agreed value: 1 RT = 12,000 BTU/hr = 3.517 kW. In metric countries the same concept is called kilowatts of cooling or sometimes a "freezing unit," but the 12,000 BTU/hr figure is universal in North American HVAC.
How to convert BTU/hr to tons of refrigeration
The formula is straightforward: divide the cooling capacity in BTU/hr by 12,000 to get refrigeration tons. For example, a 36,000 BTU/hr central air conditioner is 36,000 / 12,000 = 3 tons. Going the other way, multiply tons by 12,000 to get BTU/hr. To convert to watts, divide BTU/hr by 3.41214 (the number of BTU/hr per watt). Kilowatts are simply watts divided by 1,000. In equation form: RT = BTU/hr / 12,000; W = BTU/hr / 3.41214; kW = BTU/hr / 3,412.14.
Sizing an HVAC system: from BTU/hr to tons
Contractors use the BTU-to-ton conversion constantly because residential equipment is sold by the ton (1.5, 2, 2.5, 3, 3.5, 4, 5 ton units are the standard sizes) while Manual J heat-gain calculations spit out a total BTU/hr load. Divide the load by 12,000 and round up to the nearest available size. Oversizing is as bad as undersizing: an over-sized unit short-cycles, raises humidity, and wears out faster. A common rough rule is 20 BTU/hr per square foot for a reasonably insulated home in a moderate climate, giving a 2,000 sq ft home a load of about 40,000 BTU/hr (3.33 tons, typically sized to a 3.5-ton unit). Actual loads vary by 20-30% depending on climate zone, insulation R-values, window area, and internal heat gains.
Refrigeration tons vs. electrical kilowatts
A common point of confusion is treating 1 RT as 1.17 kW of electrical draw. That relationship comes from the unit conversion (1 RT = 3.517 kW of heat removal; 1 kW = 1 kW of electricity input), NOT from real-world efficiency. A modern inverter-driven split system may have a COP (coefficient of performance) of 3 to 5, meaning it removes 3-5 kW of heat for every 1 kW of electricity. So a 3-RT (10.55 kW cooling) unit might draw only 2-3.5 kW of power. The RT rating tells you how much heat the unit removes from the space per hour; the electrical rating (nameplate amps times voltage) tells you how much power it consumes. Both matter for system design.
Common BTU/hr to Refrigeration Tons conversions
| BTU/hr | Tons of refrig. (RT) | kBTU/hr | Kilowatts (kW) | Typical application |
|---|---|---|---|---|
| 6000 | 0.5 | 6 | 1.758 | Small portable AC |
| 8000 | 0.667 | 8 | 2.344 | Small window AC |
| 10000 | 0.833 | 10 | 2.931 | Window AC (medium room) |
| 12000 | 1 | 12 | 3.517 | 1 RT - small room/apartment |
| 18000 | 1.5 | 18 | 5.275 | Larger room / studio |
| 24000 | 2 | 24 | 7.034 | 2 RT - 2-car garage / small home |
| 36000 | 3 | 36 | 10.55 | 3 RT - typical 1,500 sq ft home |
| 48000 | 4 | 48 | 14.07 | 4 RT - larger home |
| 60000 | 5 | 60 | 17.58 | 5 RT - large home / small office |
| 120000 | 10 | 120 | 35.17 | 10 RT - small commercial |
| 240000 | 20 | 240 | 70.34 | 20 RT - mid-size commercial |
| 600000 | 50 | 600 | 175.8 | 50 RT - large commercial chiller |
1 RT = 12,000 BTU/hr exactly. Values rounded for quick reference.
Frequently asked questions
How many BTU/hr is 1 ton of refrigeration?
1 ton of refrigeration (RT) equals exactly 12,000 BTU/hr. This is the internationally agreed standard derived from the amount of heat needed to melt one short ton (2,000 lb) of ice over 24 hours: 2,000 lb x 144 BTU/lb = 288,000 BTU, divided by 24 hours = 12,000 BTU/hr.
How do I convert BTU/hr to tons for AC sizing?
Divide the BTU/hr figure by 12,000. For example, if your Manual J calculation shows a cooling load of 30,000 BTU/hr, that is 30,000 / 12,000 = 2.5 tons. You would then shop for a 2.5-ton central AC unit. If the result falls between standard sizes (e.g. 2.67 tons), round up to the next available size (3 tons) rather than down, to ensure sufficient capacity on the hottest days.
What is the difference between a ton of refrigeration and a kilowatt?
1 ton of refrigeration equals 3.517 kW of heat-removal capacity. However, this is the cooling power delivered to the space - it is not the electrical power the compressor draws. A system rated at 1 RT may use only 0.7-1.2 kW of electricity if it has a COP of 3 to 5. Always check the unit's EER or SEER rating to understand electrical consumption, not just the tonnage.
Is "ton" in air conditioning the same as a weight ton?
No. A ton of refrigeration is a unit of power (heat-removal rate), not mass. It happens to be defined in terms of weight (the heat to melt one ton of ice per day) but the result is a rate - 12,000 BTU/hr. A 3-ton AC does not weigh 3 tons; it removes heat at a rate of 36,000 BTU/hr.
How many BTU/hr is a 3-ton air conditioner?
A 3-ton air conditioner has a cooling capacity of 3 x 12,000 = 36,000 BTU/hr, or 36 kBTU/hr. In kilowatts that is 36,000 / 3,412.14 = approximately 10.55 kW of cooling capacity. It is one of the most common residential sizes, suitable for homes of roughly 1,500 to 2,100 square feet in a moderate climate.
Can I convert BTU/hr to watts using this calculator?
Yes. Select "BTU/hr" as the input unit, enter your value, and the calculator immediately shows the equivalent in watts and kilowatts. The conversion factor is 1 BTU/hr = 0.293071 watts, or equivalently 1 watt = 3.41214 BTU/hr. This is useful when comparing equipment specs that use different unit systems.
What does kBTU/hr mean?
kBTU/hr stands for kilo-BTU per hour, meaning 1,000 BTU per hour. It is simply a more convenient scale for commercial equipment - a 100 kBTU/hr chiller is the same as 100,000 BTU/hr or 8.33 tons of refrigeration. The prefix "k" (kilo) means 1,000, the same as in kilowatt.