Torque to Horsepower Calculator
One Number Changes the Other, at a Fixed Rate
Torque and horsepower describe the same rotating output measured two different ways — torque is the twisting force itself, horsepower is that force scaled by how fast it's spinning. Because the relationship is fixed by a single conversion constant, any torque and RPM pair converts to exactly one horsepower figure, with no ambiguity. This calculator is built for that direct conversion: plug in a torque reading and the RPM it was taken at, and get the equivalent horsepower back immediately.
The Formula
Metric: kW = (Torque[Nm] × RPM) ÷ 9550, then HP = kW × 1.34102
The divisor 5252 comes directly from the definition of horsepower (33,000 ft-lb per minute) divided by 2π, which is why torque and horsepower curves always cross at exactly 5,252 RPM on a dyno chart.
Where This Matters
- Reading spec sheets — manufacturers publish both peak torque and peak horsepower, each at a different RPM; converting one at the other's RPM shows how the two curves actually compare.
- Quick dyno pull checks — a dyno operator can spot-check any single torque/RPM data point against the horsepower trace to confirm the conversion is being plotted correctly.
- Gear and RPM planning — because horsepower rises with RPM even as torque falls, this conversion clarifies why higher-revving engines can out-power a torquier engine that spins to a lower redline.
- Cross-checking aftermarket parts claims — a torque figure quoted at a specific RPM converts to a horsepower number that can be checked against a separately advertised horsepower rating.
Horsepower at 4,000 RPM by Torque
| Torque (lb-ft) | Horsepower |
|---|---|
| 150 | 114.2 HP |
| 200 | 152.3 HP |
| 250 | 190.4 HP |
| 300 | 228.5 HP |
| 350 | 266.6 HP |
| 400 | 304.6 HP |
Computed directly from HP = (Torque × RPM) ÷ 5252 at a constant 4,000 RPM.
How to Use This Calculator
- Select Imperial (lb-ft) or Metric (Nm) for the torque unit.
- Enter the torque value.
- Enter the RPM at which that torque figure applies.
- Select Calculate to see the equivalent horsepower.
Related Calculations
For a fuller dyno-style breakdown including a trap-speed estimation mode, see the Horsepower Calculator, or work backward from a target horsepower with the Torque Calculator.