66 horsepower works out to 49.21619152 kW. The calculation is 66 × 0.7456998716, and the unrounded result is 49.2161915244 kilowatts, which is the number to use if this feeds into anything else.
49.2162 kW is 66 mechanical horsepower and 66.92 metric PS. Put that through a 1,400 kg car at 80% drivetrain efficiency and the energy needed to reach 100 km/h — 540.1 kJ — takes about 13.7 seconds to deliver, which is a floor rather than a real figure because it ignores drag and traction limits.
The result sits 0.7838 kW short of 50 kW, so if you need a round figure to quote, 50 kW is the honest nearest one. Plenty of people do this in their head: divide by 1.3 instead of using the exact factor 0.7456998716. At 66 that shortcut gives 50.769231 kilowatts, off by 1.553 kilowatts or about 3.16%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
The formula
66 hp- The quantity being converted
0.7456998716- Exact kilowatts in one horsepower
49.21619152 kW- The converted result
How it works, step by step
- Start with 66 horsepower.
- Multiply by 0.7456998716, the exact number of kilowatts in one horsepower.
- That gives 49.2161915244 kilowatts.
- To reverse it, divide by 0.7456998716 instead: 49.21619152 kW ÷ 0.7456998716 returns 66 hp.
Worked examples
The calculation
66 hp × 0.7456998716 = 49.2161915244 kW. One multiplication, with no rounding until the value reaches the screen.
Checking it backwards
49.21619152 kW ÷ 0.7456998716 = 66 hp. Recovering the original number is the fastest way to confirm the factor was not applied upside down.
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Frequently asked questions
What is 66 horsepower in kilowatts?
66 horsepower is exactly 49.21619152 kW. Carried to full precision that is 49.2161915244 kilowatts.
How do you convert horsepower to kilowatts?
One step: multiply the horsepower figure by 0.7456998716. Here that is 66 × 0.7456998716 = 49.21619152 kilowatts.
What is 49.21619152 kilowatts back in horsepower?
It goes back to 66 horsepower. The reciprocal of the factor is 1.34102209, so multiplying by that works just as well as dividing.
How much is 66 hp in practice?
49.2162 kW is 66 mechanical horsepower and 66.92 metric PS. Put that through a 1,400 kg car at 80% drivetrain efficiency and the energy needed to reach 100 km/h — 540.1 kJ — takes about 13.7 seconds to deliver, which is a floor rather than a real figure because it ignores drag and traction limits. Compare it against the surrounding values in the table below.
What is a horsepower?
Mechanical horsepower, defined by James Watt as 550 foot-pounds per second.
What is a kilowatt?
The rating unit for motors, EV chargers and solar arrays.
66 hp in kilowatts — nearby values
| Horsepower | Kilowatts | Unrounded |
|---|---|---|
| 60 hp | 44.741992 | 44.74199229 |
| 61 hp | 45.487692 | 45.48769217 |
| 62 hp | 46.233392 | 46.23339204 |
| 63 hp | 46.979092 | 46.97909191 |
| 64 hp | 47.724792 | 47.72479178 |
| 65 hp | 48.470492 | 48.47049165 |
| 66 hp | 49.216192 | 49.21619152 |
| 67 hp | 49.961891 | 49.9618914 |
| 68 hp | 50.707591 | 50.70759127 |
| 69 hp | 51.453291 | 51.45329114 |
| 70 hp | 52.198991 | 52.19899101 |
| 71 hp | 52.944691 | 52.94469088 |
| 72 hp | 53.690391 | 53.69039075 |
Exact factor: 1 horsepower = 0.745699871582 kilowatts. The row for 66 hp is the value this page is about.