Refrigeration ton to kW
Convert between refrigeration tons, kW, kcal/h and Btu/h. The US ton and the Japanese ton differ by about 10 %, so both are shown side by side.
Open the full 12-category converter
What a refrigeration ton is
A refrigeration ton is the cooling rate that freezes one ton of water at 0 °C into ice in 24 hours. The "ton" is a rate of heat removal, not a weight.
The US ton (USRT) uses 2,000 lb and the latent heat of ice, 144 Btu/lb: 2,000 × 144 ÷ 24 = 12,000 Btu/h = 3.517 kW. The Japanese ton (JRT) uses 1,000 kg and 79.68 kcal/kg: 1,000 × 79.68 ÷ 24 = 3,320 kcal/h = 3.861 kW.
USRT vs JRT
1 JRT ÷ 1 USRT = 3.861 ÷ 3.517 = 1.098, so the Japanese ton is about 9.8 % larger. For a 100-ton chiller that is 351.7 kW (USRT) against 386.1 kW (JRT), a 34 kW gap.
US-rated equipment (chillers, packaged units, cooling towers) uses USRT. Korean and Japanese textbooks and exam problems often state 1 RT = 3,320 kcal/h. Check whether a figure comes from Btu/h or kcal/h before converting it.
Conversion formulas
- kW = USRT × 3.5169 (1 USRT = 12,000 Btu/h)
- kW = JRT × 3.8612 (1 JRT = 3,320 kcal/h)
- kcal/h = kW × 859.85 (1 kcal = 4.1868 kJ), about 860
- Btu/h = kW × 3,412.14 (1 Btu = 1.05506 kJ)
- USRT = kW ÷ 3.5169, JRT = kW ÷ 3.8612
Cooling capacity kW vs power input kW
The kW you convert to tons is the heat the unit removes (capacity), not the electric power on the bill. Their ratio is COP = capacity ÷ power input; a 10-ton (35.2 kW) unit with a COP of 3.5 draws about 10 kW.
"One horsepower per ton" is an old compressor rule of thumb, not a unit equality: 1 HP is 0.746 kW of shaft power, 1 ton is 3.517 kW of cooling.
Refrigeration ton table (1 to 100 tons)
kW, kcal/h and Btu/h for the same ton figure read as US tons and as Japanese tons. Same factors as the converter above.
| Tons (RT) | USRT kW | USRT kcal/h | USRT Btu/h | JRT kW | JRT kcal/h | JRT Btu/h |
|---|---|---|---|---|---|---|
| 1 | 3.517 | 3,024 | 12,000 | 3.861 | 3,320 | 13,175 |
| 2 | 7.034 | 6,048 | 24,000 | 7.722 | 6,640 | 26,350 |
| 3 | 10.551 | 9,072 | 36,000 | 11.583 | 9,960 | 39,524 |
| 4 | 14.067 | 12,096 | 48,000 | 15.445 | 13,280 | 52,699 |
| 5 | 17.584 | 15,120 | 60,000 | 19.306 | 16,600 | 65,874 |
| 6 | 21.101 | 18,144 | 72,000 | 23.167 | 19,920 | 79,049 |
| 7 | 24.618 | 21,168 | 84,000 | 27.028 | 23,240 | 92,224 |
| 8 | 28.135 | 24,192 | 96,000 | 30.889 | 26,560 | 105,399 |
| 9 | 31.652 | 27,216 | 108,000 | 34.750 | 29,880 | 118,573 |
| 10 | 35.169 | 30,239 | 120,000 | 38.612 | 33,200 | 131,748 |
| 15 | 52.753 | 45,359 | 180,000 | 57.917 | 49,800 | 197,622 |
| 20 | 70.337 | 60,479 | 240,000 | 77.223 | 66,400 | 263,496 |
| 25 | 87.921 | 75,599 | 300,000 | 96.529 | 83,000 | 329,371 |
| 30 | 105.506 | 90,718 | 360,000 | 115.835 | 99,600 | 395,245 |
| 40 | 140.674 | 120,958 | 480,000 | 154.446 | 132,800 | 526,993 |
| 50 | 175.843 | 151,197 | 600,000 | 193.058 | 166,000 | 658,741 |
| 60 | 211.011 | 181,437 | 720,000 | 231.670 | 199,200 | 790,489 |
| 70 | 246.180 | 211,676 | 840,000 | 270.281 | 232,400 | 922,238 |
| 80 | 281.348 | 241,916 | 960,000 | 308.893 | 265,600 | 1,053,986 |
| 90 | 316.517 | 272,155 | 1,080,000 | 347.504 | 298,800 | 1,185,734 |
| 100 | 351.685 | 302,395 | 1,200,000 | 386.116 | 332,000 | 1,317,482 |
kW to refrigeration ton table
Common catalogue cooling capacities in kW, converted to tons and kcal/h.
| Capacity kW | USRT RT | JRT RT | kcal/h | Btu/h |
|---|---|---|---|---|
| 1 | 0.284 | 0.259 | 860 | 3,412 |
| 2.5 | 0.711 | 0.647 | 2,150 | 8,530 |
| 3.5 | 0.995 | 0.906 | 3,009 | 11,942 |
| 5 | 1.422 | 1.295 | 4,299 | 17,061 |
| 7 | 1.990 | 1.813 | 6,019 | 23,885 |
| 10 | 2.843 | 2.590 | 8,598 | 34,121 |
| 14 | 3.981 | 3.626 | 12,038 | 47,770 |
| 20 | 5.687 | 5.180 | 17,197 | 68,243 |
| 28 | 7.962 | 7.252 | 24,076 | 95,540 |
| 35 | 9.952 | 9.065 | 30,095 | 119,425 |
| 50 | 14.217 | 12.949 | 42,992 | 170,607 |
| 70 | 19.904 | 18.129 | 60,189 | 238,850 |
| 100 | 28.435 | 25.899 | 85,985 | 341,214 |
| 175 | 49.760 | 45.323 | 150,473 | 597,125 |
| 350 | 99.521 | 90.646 | 300,946 | 1,194,250 |
| 500 | 142.173 | 129.495 | 429,923 | 1,706,071 |
| 1,000 | 284.345 | 258.990 | 859,845 | 3,412,142 |
Sources
- ASHRAE Handbook, Fundamentals (SI), chapter "Units and Conversions": 1 ton of refrigeration = 12,000 Btu/h = 3.517 kW
- Fifth International Conference on the Properties of Steam, 1956 (IT calorie 4.1868 J, IT Btu 1055.05585262 J)
- Japanese refrigeration ton, 3,320 kcal/h: conventional value in Japanese and Korean refrigeration practice (79.68 kcal/kg × 1,000 kg ÷ 24 h)
Frequently asked questions
How many kW is a 10-ton unit?
With US tons, 10 × 3.5169 = 35.17 kW (120,000 Btu/h). With Japanese tons, 10 × 3.8612 = 38.61 kW (33,200 kcal/h). Equipment catalogues almost always use US tons.
How do I convert an air conditioner kW rating to tons?
Divide the cooling capacity in kW by 3.5169 to get US tons: a 7 kW unit is about 2.0 tons and a 28 kW system about 8.0 tons. Use the cooling capacity, not the power input.
Is a refrigeration ton the same as a horsepower?
No. Horsepower is shaft power (1 HP = 0.746 kW) and a ton is cooling capacity (1 US ton = 3.517 kW). The old saying that one compressor horsepower gives about one ton is only a rule of thumb.
Last updated 2026-10-12.