Power Converter (W, kW, hp, BTU/h)
Type in either box to turn hp into kW, BTU/h into watts, PS into hp or any pair of power units, with the answer in every unit at once.
Type in either box. Tap a unit under a box to change it.
Uses the power above. Energy = power × time; cost = kWh × your price per unit of electricity.
Power factor is 1 for heaters and kettles, about 0.8 to 0.95 for motors. For kVA, amps and kVAR use the kVA, kW and amps converter.
Decibels can be negative (−30 dBm is 1 µW), so they have their own box.
hp (mech) to kW table
Common values both ways. Change the units above and the table follows.
| hp (mech) | kW |
|---|---|
| 1 | 0.7456999 |
| 2 | 1.4914 |
| 5 | 3.728499 |
| 10 | 7.456999 |
| 25 | 18.6425 |
| 50 | 37.28499 |
| 75 | 55.92749 |
| 100 | 74.56999 |
| 150 | 111.855 |
| 200 | 149.14 |
| 250 | 186.425 |
| 300 | 223.71 |
| 400 | 298.2799 |
| 500 | 372.8499 |
| 750 | 559.2749 |
| 1,000 | 745.6999 |
| kW | hp (mech) |
|---|---|
| 1 | 1.341022 |
| 2 | 2.682044 |
| 5 | 6.70511 |
| 10 | 13.41022 |
| 25 | 33.52555 |
| 50 | 67.0511 |
| 75 | 100.5767 |
| 100 | 134.1022 |
| 150 | 201.1533 |
| 200 | 268.2044 |
| 250 | 335.2555 |
| 300 | 402.3066 |
| 400 | 536.4088 |
| 500 | 670.511 |
| 750 | 1,005.767 |
| 1,000 | 1,341.022 |
Common examples
- Person cycling hard (generic)250 W = 0.25 kW = 0.3 hp (mech)
- Kettle (typical)2,000 W = 2.00 kW = 2.7 hp (mech)
- Small city car engine (generic)75 PS = 55.16 kW = 74.0 hp (mech)
- Family car engine (generic)150 hp (mech) = 111.85 kW = 150.0 hp (mech)
- Sports car engine (generic)500 hp (mech) = 372.85 kW = 500.0 hp (mech)
- Pool pump motor (generic)1.5 hp (elec) = 1.12 kW = 1.5 hp (mech)
- Split AC unit (typical)12,000 BTU/h = 3.52 kW = 1.00 TR
- Small light aircraft engine (generic)180 hp (mech) = 134.23 kW = 180.0 hp (mech)
- Wind turbine (typical onshore)3 MW = 3,000 kW = 4,023 hp (mech)
- Wi-Fi router transmit power (typical)100 mW = 0.0001 kW = 0.1 W
“Generic” and “typical” figures are everyday illustrations, not the output of any one engine, car or device.
The four horsepowers
| Type | Watts | In kW | Where it’s used |
|---|---|---|---|
| Mechanical (imperial) hp | 745.69987 | 0.7457 | 550 ft·lbf/s. US and UK car and aircraft engines |
| Metric hp (PS, CV, ch, pk) | 735.49875 | 0.7355 | 75 kgf·m/s. Cars in Europe, Japan, India |
| Electrical hp | 746 | 0.7460 | Electric motor nameplates |
| Boiler hp | 9,809.5 | 9.8095 | Steam boilers: about 33,471 BTU/h |
How your power is converted
Every unit goes into watts first, then out to the unit you want.
- 1
Your power
100 hp (mech) →
kW - 2
Into watts
100 × 745.6999 =
74,569.99 W - 3
Out to kW
74,569.99 ÷ 1,000 =
74.56999 kW - 4
The shortcut
1 hp (mech) =
0.7456999 kW
Read more: the formula, a worked example, the four horsepowers, AC tons, dBm and volts × amps
The formula
watts = your number × watts in one of your unit
answer = watts ÷ watts in one of the unit you want
hp → kW: kW = hp × 0.7457
kW → hp: hp = kW × 1.341
BTU/h → kW: kW = BTU/h × 0.00029307
dBm = 10 × log₁₀(milliwatts)
Worked example
100 mechanical hp in kW. First into watts, where 1 hp is 745.69987 W: 100 × 745.69987 = 74,569.987 W. Then out to kW, where 1 kW is 1,000 W: 74,569.987 ÷ 1,000 = 74.569987 kW, about 74.57 kW. As a shortcut, 1 hp = 0.7457 kW.
With metric horsepower instead: 100 PS × 735.49875 W = 73,549.875 W = 73.55 kW. An air conditioner of 12,000 BTU/h: 12,000 × 0.29307107 = 3,516.85 W = 3.517 kW, which is exactly 1 ton of refrigeration.
AC tons, BTU/h and kW
| AC size | BTU/h | kW of cooling |
|---|---|---|
| 0.75 TR | 9,000 | 2.64 |
| 1 TR | 12,000 | 3.52 |
| 1.5 TR | 18,000 | 5.28 |
| 2 TR | 24,000 | 7.03 |
| 2.5 TR | 30,000 | 8.79 |
| 3 TR | 36,000 | 10.55 |
| 5 TR | 60,000 | 17.58 |
Volts × amps
DC: watts = volts × amps. Single-phase AC: watts = volts × amps × power factor. Three-phase AC: watts = √3 × volts × amps × power factor, with the line-to-line voltage. Example: 400 V × 10 A × 0.8 × 1.7321 = 5,542.6 W = 5.54 kW. Without the power factor you get apparent power: 6.93 kVA.
dBm and dBW
Radio and audio engineers use decibels: dBm = 10 × log₁₀(power ÷ 1 mW) and dBW = dBm − 30. So 0 dBm = 1 mW, 20 dBm = 100 mW, 30 dBm = 1 W and 60 dBm = 1 kW. Add 3 dB and the power roughly doubles; add 10 dB and it is 10 times more.
Power or energy?
Power (W, hp, BTU/h) is how fast energy is used. Energy (Wh, kWh, BTU, joules) is the amount. A 1.5 kW heater for 3 hours uses 1.5 × 3 = 4.5 kWh. For energy units, use the energy converter.
Factors: mechanical hp = 550 ft·lbf/s = 745.69987158 W; metric hp = 735.49875 W; electrical hp = 746 W; boiler hp = 9,809.5 W; BTU/h uses the International Table BTU (1,055.05585262 J), so 1 BTU/h = 0.29307107 W and 1 TR = 12,000 BTU/h = 3,516.8528 W; kcal/h uses the IT kilocalorie, so 1 kcal/h = 1.163 W. Checked 15 October 2026 against NIST Special Publication 811.
Common questions
How many kW is 1 horsepower?
One mechanical (imperial) horsepower is 0.7457 kW (745.7 W). One metric horsepower (PS) is 0.7355 kW, and one electrical horsepower is exactly 0.746 kW. To turn hp into kW, multiply by 0.7457; to turn kW into hp, multiply by 1.341.
What is the difference between hp and PS?
PS (Pferdestärke, also CV or ch) is metric horsepower: 735.5 W. Mechanical hp is 745.7 W, about 1.4% bigger. So 100 PS is 98.6 hp, or 73.55 kW. European and Asian car brochures often give PS; US and UK ones give hp.
How many kW is 12,000 BTU/h?
12,000 BTU per hour is 3.517 kW, which is 1 ton of refrigeration. Multiply BTU/h by 0.00029307 to get kW. This is cooling power, not the electricity the AC uses, which is usually 3 to 4 times lower.
How do I work out kW from volts and amps?
For DC, kW = volts × amps ÷ 1,000. For single-phase AC, multiply by the power factor too. For three-phase, multiply by √3 (1.732) as well, using the line-to-line voltage: 400 V × 10 A × 0.8 × 1.732 = 5.54 kW. Advanced does this for you.
How do I convert watts to dBm?
dBm = 10 × log₁₀(power in milliwatts). So 1 mW is 0 dBm, 100 mW is 20 dBm and 1 W is 30 dBm. Every 3 dB is about double the power. dBW is the same idea relative to 1 watt, so dBW = dBm − 30.
Is a watt the same as a watt-hour?
No. A watt is power, how fast energy is used. A watt-hour is energy, the amount used. A 2,000 W kettle running for 3 minutes (0.05 h) uses 2,000 × 0.05 = 100 Wh, or 0.1 kWh. Advanced works out energy and cost from any power.
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