Power Unit Conversion
Quick answer: 1 kW = 1,000 W ≈ 1.34 hp ≈ 1.36 PS ≈ 3,412 BTU/h ≈ 860 kcal/h; 1 hp = 745.7 W, 1 PS = 735.5 W and 1 ton of refrigeration = 3.517 kW.
Watts, kilowatts, megawatts, horsepower (PS and hp), BTU/h, kcal/h and tons of refrigeration – enter a value and see every conversion at once.
How the calculation works
Enter a power and choose the starting unit (for example kW, hp or BTU/h). The table shows the same power in watts, kilowatts and megawatts, in metric (PS) and mechanical (hp) horsepower, in BTU/h and kcal/h and in tons of refrigeration. With “Show all” you also see electrical and boiler horsepower, BTU/s, kcal/s, cal/s, erg/s and ft·lbf/s.
Formula and assumptions
The base unit is the watt (1 W = 1 J/s). 1 hp (mechanical) = 550 ft·lbf/s = 745.69987 W; 1 PS (metric horsepower, CV) = 75 kgf·m/s = 735.49875 W; electrical hp = 746 W. Heat units use the International Table calorie and BTU: 1 kcal/h = 1.163 W, 1 BTU/h = 0.29307107 W, 1 ton of refrigeration = 12,000 BTU/h = 3,516.85 W.
More worked examples
- A 110 kW engine in hp: 110 ÷ 0.74569987 ≈ 147.5 hp.
- A 12,000 BTU/h air conditioner in kW: 12,000 × 0.29307 ≈ 3.52 kW.
- A 24 kW boiler in kcal/h: 24,000 ÷ 1.163 ≈ 20,636 kcal/h.
- A 5 hp generator in kW: 5 × 0.7457 ≈ 3.73 kW.
Units of power
| Unit | in W | Other |
|---|---|---|
| 1 W | 1 | 1 J/s |
| 1 kW | 1,000 | ≈ 1.341 hp ≈ 3,412.14 BTU/h |
| 1 hp | 745.700 | 550 ft·lbf/s |
| 1 PS (metric hp) | 735.499 | 75 kgf·m/s |
| 1 BTU/h | 0.293071 | ≈ 0.252 kcal/h |
| 1 kcal/h | 1.163 | ≈ 3.968 BTU/h |
| 1 TR | 3,516.85 | 12,000 BTU/h |
Common mistakes
- Mixing up metric horsepower (PS = 735.5 W) and mechanical horsepower (hp = 745.7 W) – they differ by about 1.4 %.
- Confusing power (kW) with energy (kWh): kWh is energy used, not power.
- For air conditioners, confusing cooling capacity (BTU/h, kW) with the electrical power the unit draws.
- Rounding a ton of refrigeration to 3.5 kW on larger systems instead of 3.517 kW.
Frequently asked questions
How many horsepower is 1 kW?
1 kW = 1,000 ÷ 745.69987 ≈ 1.341 hp (or 1.36 PS). Conversely, 1 hp = 0.7457 kW, so a 100 hp engine is about 74.6 kW.
What is the difference between PS and hp?
PS (CV, ch) is metric horsepower of 735.5 W, while hp is mechanical (imperial) horsepower of 745.7 W. For the same engine the figure in hp is about 1.4 % lower than in PS.
How many kW is 12,000 BTU/h?
12,000 BTU/h × 0.29307 W ≈ 3,517 W, or about 3.5 kW. That is also exactly one ton of refrigeration (TR).
How many kcal/h is 1 kW?
1 kW = 1,000 ÷ 1.163 ≈ 860 kcal/h. Older boilers and heaters were often rated in kcal/h.
Is kW the same as kWh?
No. kW is power (how fast energy is used or produced) and kWh is energy: a 2 kW appliance running for 3 hours uses 6 kWh. The converter only converts units of power.
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