Enter a non‑negative value.
Revolutions per minute.
Horsepower (hp)
—
Power (kW)
—
Formula snapshot
hp = (Tlb‑ft × RPM) / 5252 |
kW = (TN·m × RPM) / 9549.297
Results are rounded to 4 decimal places. Logged into the table below.
Conversion History
| # | Timestamp | Torque | Unit | RPM | hp | kW |
|---|
Example Data
These examples illustrate typical power outputs across common automotive and industrial scenarios.
| # | Torque | Unit | RPM | hp | kW | Notes |
|---|
Quick Reference (lb‑ft): hp & kW at Common RPM
| # | Torque (lb‑ft) | RPM | hp | kW |
|---|---|---|---|---|
| 1 | 100 | 1500 | 28.5605 | 21.2976 |
| 2 | 100 | 3000 | 57.1211 | 42.5952 |
| 3 | 150 | 3000 | 85.6816 | 63.8928 |
| 4 | 200 | 3000 | 114.2422 | 85.1904 |
| 5 | 250 | 3000 | 142.8027 | 106.4880 |
| 6 | 300 | 3000 | 171.3633 | 127.7856 |
| 7 | 300 | 4500 | 257.0449 | 191.6784 |
Quick Reference (N·m): hp & kW at Common RPM
| # | Torque (N·m) | RPM | hp | kW |
|---|---|---|---|---|
| 1 | 100 | 1500 | 21.0647 | 15.7080 |
| 2 | 100 | 3000 | 42.1294 | 31.4159 |
| 3 | 200 | 3000 | 84.2589 | 62.8319 |
| 4 | 300 | 3000 | 126.3883 | 94.2478 |
| 5 | 400 | 3000 | 168.5178 | 125.6637 |
| 6 | 500 | 3000 | 210.6472 | 157.0796 |
Formula Used
Imperial (lb‑ft → hp)
hp = ( Tlb‑ft × RPM ) / 5252
Constant 5252 derives from 1 hp = 550 ft·lbf/s and ω = 2π·RPM/60.
Metric (N·m → kW, hp)
kW = ( TN·m × RPM ) / 9549.297
hp = kW × 1.34102209 ≈ ( TN·m × RPM ) / 7120.91
hp = kW × 1.34102209 ≈ ( TN·m × RPM ) / 7120.91
The 9549.297 constant comes from ω = 2π·RPM/60 and 1 kW = 1000 W.
Notes
- Use consistent units: lb‑ft for the 5252 relation, N·m for the 9549.297 relation.
- Results assume steady‑state rotational speed and neglect drivetrain losses.
How to Use This Calculator
- Enter torque value.
- Select the torque unit: lb‑ft or N·m.
- Enter RPM.
- Click Calculate to see hp and kW.
- Each calculation logs into the history table automatically.
- Use the CSV or PDF buttons to export history or examples.
- Click Copy Link to share prefilled inputs.
FAQs
It comes from combining mechanical horsepower definition with angular speed in radians per second. Specifically, hp = T × ω / 550 and ω = 2π·RPM/60, giving 5252 in the denominator.
Yes. The app computes kW using kW = T × RPM / 9549.297 and then converts to hp using hp = kW × 1.34102209, which is equivalent to hp ≈ T × RPM / 7120.91.
Values are rounded to four decimal places by default. Internally, calculations use double‑precision floats and the constants shown above.
Displaying both is convenient for mixed specifications. Some datasheets use horsepower, others use kilowatts. Showing both reduces conversion steps and potential rounding differences.
No. The formulas compute shaft power at the point of torque measurement. Real systems may deliver less usable power due to losses downstream.
Use the history table as you calculate. The CSV and PDF buttons export all rows currently listed. You can clear the table to keep only desired runs.