hp to Torque Converter
An engine making 100 hp at 3,000 rpm produces about 175 lb-ft of torque.
Quick answer: Multiply the horsepower by 5,252, then divide by the rpm. For example, 100 hp at 3,000 rpm is 175.07 lb-ft, 300 hp at 5,000 rpm is 315.13 lb-ft and 50 hp at 1,800 rpm is 145.89 lb-ft.
The hp to torque formula
Torque in lb-ft equals horsepower times 5,252 divided by rpm.
Multiply the lb-ft by 1.3558 to get newton metres.
Take 100 hp at 3,000 rpm. 100 × 5,252 ÷ 3,000 gives 175.07 lb-ft.
Take 300 hp at 5,000 rpm. 300 × 5,252 ÷ 5,000 gives 315.13 lb-ft.
Where 5,252 comes from
One horsepower is 33,000 foot-pounds per minute. Dividing by 2 pi radians per turn gives the constant 5,252 (Wikipedia: Horsepower).
So torque in lb-ft times rpm divided by 5,252 equals horsepower, and the formula here runs the other way.
How to convert hp to torque step by step
- Read the power in horsepower and the engine speed in rpm.
- Multiply the horsepower by 5,252.
- Divide by the rpm to get lb-ft.
- Multiply by 1.3558 if you want N m.
Example 1: 100 hp at 3,000 rpm
- Start with 100 hp at 3,000 rpm.
- 100 × 5,252 ÷ 3,000 = 175.07.
- The torque is 175.07 lb-ft.
100 hp at 3,000 rpm = 175.07 lb-ft
Example 2: 300 hp at 5,000 rpm
- Start with 300 hp at 5,000 rpm.
- 300 × 5,252 ÷ 5,000 = 315.13.
- The torque is 315.13 lb-ft.
300 hp at 5,000 rpm = 315.13 lb-ft
Example 3: 50 hp at 1,800 rpm
- Start with 50 hp at 1,800 rpm.
- 50 × 5,252 ÷ 1,800 = 145.89.
- The torque is 145.89 lb-ft.
50 hp at 1,800 rpm = 145.89 lb-ft
The three examples below use common sizes.
Each one shows the sum in full.
hp to torque conversion table
| Power and speed | Torque (lb-ft) | Torque (N m) |
|---|---|---|
| 10 hp at 1,800 rpm | 29.178 lb-ft | 39.561 N m |
| 20 hp at 3,000 rpm | 35.014 lb-ft | 47.473 N m |
| 50 hp at 1,800 rpm | 145.89 lb-ft | 197.8 N m |
| 75 hp at 3,000 rpm | 131.3 lb-ft | 178.02 N m |
| 100 hp at 2,000 rpm | 262.61 lb-ft | 356.05 N m |
| 100 hp at 3,000 rpm | 175.07 lb-ft | 237.36 N m |
| 100 hp at 5,252 rpm | 100 lb-ft | 135.58 N m |
| 150 hp at 4,000 rpm | 196.95 lb-ft | 267.03 N m |
| 200 hp at 6,000 rpm | 175.07 lb-ft | 237.36 N m |
| 300 hp at 5,000 rpm | 315.13 lb-ft | 427.25 N m |
| 400 hp at 6,500 rpm | 323.21 lb-ft | 438.21 N m |
| 500 hp at 7,000 rpm | 375.15 lb-ft | 508.64 N m |
The highlighted row is the default of the calculator. The last column gives N m.
A quick mental shortcut for hp to torque
At 5,252 rpm, the torque in lb-ft equals the horsepower. So 300 hp at 5,252 rpm is 300 lb-ft.
Below that speed the torque number is bigger than the hp number, and above it the torque number is smaller (Firgelli: Horsepower to Torque Converter).
The crossover at 5,252 rpm
At 5,252 rpm the formula gives the same number for horsepower and torque in lb-ft. Every dyno chart that plots both curves shows them crossing there.
It is a result of the units, not of any engine.
Metric units
In metric, torque in N m equals 9,549 times the power in kW divided by the rpm (Firgelli: Horsepower to Torque Converter). The table on this page already shows N m in the last column.
Both routes give the same answer.
Peak power and peak torque
An engine rarely makes its peak torque and peak power at the same speed. Use the rpm where each peak occurs.
A figure at the wrong rpm will mislead you.
Quick conversion answers
| Conversion | Result |
|---|---|
| 100 hp at 2,000 rpm | 262.61 lb-ft |
| 100 hp at 3,000 rpm | 175.07 lb-ft |
| 100 hp at 5,252 rpm | 100 lb-ft |
| 300 hp at 5,000 rpm | 315.13 lb-ft |
Where this conversion is used
Tuners turn a power figure into torque at a chosen rpm.
Buyers compare engines that quote only one of the two.
Common mistakes to avoid
- Using the wrong rpm. Torque depends on the speed you pick.
- Mixing lb-ft and N m. Multiply by 1.3558 to move to N m.
- Using this for electric motors in kW. Convert to hp first or use the kW form.
- Treating lb-ft and ft-lbs per minute as the same. Torque is not power.
Related converters
More power and speed pairs
5 hp at 1,200 rpm is 21.88 lb-ft. 15 hp at 1,800 rpm is 43.77 lb-ft. 40 hp at 2,500 rpm is 84.03 lb-ft.
60 hp at 3,600 rpm is 87.54 lb-ft. 120 hp at 4,500 rpm is 140.1 lb-ft. 180 hp at 5,500 rpm is 171.9 lb-ft.
250 hp at 6,000 rpm is 218.8 lb-ft. 350 hp at 6,500 rpm is 282.8 lb-ft. 450 hp at 7,000 rpm is 337.6 lb-ft.
Doubling the first number
10 hp at 1,200 rpm is 43.77 lb-ft. 30 hp at 1,800 rpm is 87.54 lb-ft. 80 hp at 2,500 rpm is 168.1 lb-ft.
120 hp at 3,600 rpm is 175.1 lb-ft. 240 hp at 4,500 rpm is 280.1 lb-ft. 360 hp at 5,500 rpm is 343.8 lb-ft.
500 hp at 6,000 rpm is 437.7 lb-ft. 700 hp at 6,500 rpm is 565.6 lb-ft. 900 hp at 7,000 rpm is 675.3 lb-ft.
Same power at different speeds
100 hp at 1,000 rpm is 525.2 lb-ft. 100 hp at 2,500 rpm is 210.1 lb-ft. 100 hp at 5,252 rpm is 100 lb-ft.
100 hp at 7,000 rpm is 75.03 lb-ft.
Frequently asked questions
How do I convert hp to torque?
Multiply the horsepower by 5,252, then divide by the rpm. The answer is in lb-ft.
How much torque is 100 hp at 3,000 rpm?
About 175 lb-ft, or 237 N m.
Why is 5,252 used?
It is 33,000 divided by 2 pi, the link between work per minute and turns per minute.
When are hp and torque equal?
At 5,252 rpm, when torque is in lb-ft.
Can I use kW instead of hp?
Yes. Multiply kW by 9,549 and divide by rpm to get N m.
Is this the peak torque?
No. It is the torque at the rpm you enter.
Sources
- Wikipedia: Horsepower (en.wikipedia.org)
- Firgelli: Horsepower to Torque Converter (firgelliauto.com)
