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Enter your values, then click Calculate result.How this calculator helps
This horsepower calculator converts torque and rotational speed at the same operating point into shaft power. Enter torque in newton metres and speed in revolutions per minute. The result reports kilowatts, mechanical horsepower and metric horsepower so the unit definition remains visible. It does not estimate engine output from vehicle weight, acceleration or advertised peak torque. A torque measurement and an rpm measurement must describe the same shaft under the same conditions; pairing unrelated maxima creates a fictional operating point.
How to use it
- 1
Read the labeled input units and select the supported calculation mode where available.
- 2
Enter the values established from the source records described below; do not substitute a different measurement basis.
- 3
Click Calculate result to calculate from the supplied inputs.
- 4
Read the main output together with the checks and limitations. After editing inputs, click Calculate again to update the stored result.
Formula and methodology
Power W = torque N·m × rpm × 2π/60. Mechanical hp = W/745.6998715822702. Metric PS = W/735.49875.
The calculator applies the displayed arithmetic to the values entered on this device. It does not silently load a local tax rate, currency conversion or commercial assumption.
Worked calculation example
At 200 N·m and 3,000 rpm, angular speed is 100π rad/s and shaft power is approximately 62.831853 kW, 84.258903 mechanical hp or 85.427546 PS.
How to interpret your result
Read the kilowatt result as torque multiplied by angular speed. The two horsepower outputs are alternative units for that same power, not separate measurements. The page keeps the direct operating-point calculation separate from vehicle elapsed-time estimates and motor-efficiency analysis. A result is meaningful only when both inputs describe a common shaft and operating condition.
For different inputs or formulas, use Torque Converter; Megawatt Calculator; Quarter Mile Calculator.
Related questions this calculator covers
- horsepower calculator
Scenario comparison
| Scenario | What it shows |
|---|---|
| Zero rpm with 200 N·m | zero shaft power. |
| 100 N·m at 6,000 rpm | the same power as 200 N·m at 3,000 rpm. |
| One kW | approximately 1.341022 mechanical hp and 1.359622 PS. |
Common mistakes to avoid
- Pairing peak torque with an unrelated maximum rpm.
- Treating metric PS as identical to mechanical hp.
- Calling electrical input power measured shaft output without efficiency evidence.
Independently calculate 2π times rpm divided by sixty, then multiply by torque. Convert the watt result using the labeled horsepower definition. Scaling either torque or rpm by two should scale every power output by two. Compare only matching measurement locations and do not introduce a hidden loss factor.
Authoritative reference. NIST lists power-unit definitions. The torque × angular-speed identity is implemented directly; no empirical vehicle model is used.What can affect the result?
Match torque with its operating speed
An engine specification may list peak torque at one speed and peak power at another. Use the torque actually associated with the entered rpm, rather than combining the highest number in each column. A dynamometer trace or a documented motor operating point provides a more meaningful pair. The formula describes instantaneous steady operating power; it does not integrate a changing torque curve across a drive cycle or establish average fuel consumption. Retain the shaft and measurement conditions with the calculation.
Mechanical horsepower and metric PS
Mechanical horsepower and metric horsepower are different unit definitions. A number marked PS or metric hp should not automatically be compared with a number marked mechanical hp as though they were identical. The calculator derives both from the same watt result instead of silently renaming one unit. This distinction changes the displayed number without changing the physical power. Electrical input power, shaft output power and brake horsepower also describe different measurement locations, even when each is expressed using a power unit.
Why torque alone is insufficient
A high static torque can occur while a shaft is not rotating. At zero rpm the modeled mechanical power is zero because angular speed is zero. At a fixed torque, doubling rpm doubles power. At a fixed rpm, doubling torque also doubles power. These are relationships within the supplied operating model, not predictions that a motor can sustain every torque and speed combination. Equipment limits, thermal behavior and control conditions determine which operating points can actually occur.
Do not infer losses or vehicle performance
The calculation has no automatic drivetrain-loss correction, chassis weight, tyre grip or gearing model. Wheel torque and engine torque must not be substituted for one another without an independently established measurement basis. A peak horsepower number does not by itself determine a quarter-mile time or towing capability. If you use the related quarter-mile calculator, keep its empirical coefficient and effective-power assumptions separate from this direct torque-and-speed identity. Neither result is a guarantee of a real vehicle outcome.
Rounding and measurement quality
The interface displays several decimal places to help reconcile arithmetic, but the source torque and speed determine practical accuracy. A torque measurement rounded to the nearest ten newton metres does not support reporting a highly precise physical output. For a manual check, first convert rpm to radians per second, multiply by torque and then apply the required unit factor. Preserve unrounded intermediate values when comparing with another application, and round only the final report to a precision justified by the measurements.
Privacy and browser processing
Values entered on this page are processed in the current browser session. SolvePilot does not require an account and does not receive the values entered into the calculator. Refreshing or closing the page clears the working values unless the browser itself restores a previous session. Avoid entering identifying or account information because the calculation needs summary values only.
Accuracy and verification
Accuracy depends first on input quality. Confirm definitions, scales, dates and source information before entering a value. Keep an independent record of any result used for planning because this page does not create an official statement or retain a calculation history.
Limits of this estimate
Read the kilowatt result as torque multiplied by angular speed. The two horsepower outputs are alternative units for that same power, not separate measurements. The page keeps the direct operating-point calculation separate from vehicle elapsed-time estimates and motor-efficiency analysis. A result is meaningful only when both inputs describe a common shaft and operating condition. The interface displays several decimal places to help reconcile arithmetic, but the source torque and speed determine practical accuracy. A torque measurement rounded to the nearest ten newton metres does not support reporting a highly precise physical output. For a manual check, first convert rpm to radians per second, multiply by torque and then apply the required unit factor. Preserve unrounded intermediate values when comparing with another application, and round only the final report to a precision justified by the measurements.
Sources and review information
Frequently asked questions
Can torque alone give horsepower?＋
No. Rotational speed at the same operating point is also required. Static torque with zero speed gives zero modeled shaft power.
Are hp and PS the same?＋
No. Mechanical horsepower and metric horsepower use different watt factors. The page labels both rather than treating the names as interchangeable.
Can I enter peak torque and peak rpm?＋
Only if that torque actually occurs at that rpm. Unrelated maxima do not define a real measured operating point.
Does this calculate wheel horsepower?＋
It calculates power for whichever shaft your torque and speed describe. No drivetrain-loss percentage is supplied or inferred.
Can I calculate negative power?＋
This worksheet accepts non-negative torque and speed magnitudes. Signed power-flow analysis requires a model with explicit directional conventions.