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Horsepower Calculator

Use this horsepower calculator to convert compatible units or encoded values for horsepower.

Primary answer
Horsepower
Inputs to verify
Solve for, Torque, and Torque unit
Use type
Use as an estimate that depends on assumptions.
Keyword intent
horsepower calculator

Calculator

Horsepower Calculator

Calculates horsepower from solve for, torque, torque unit. Defaults are filled in so you can review a working example before changing inputs.

Choose the unknown value in rotational power.

Known torque. Required unless solving for torque.

Unit for the torque input.

rpm

Known rotational speed. Required unless solving for RPM.

hp

Known mechanical horsepower. Required unless solving for horsepower.

Result

Result reflects the current submitted inputs.

  • Risk B
  • Reviewed 2026-05-26
  • 3 sources
Horsepower228.4795 hp
Power170.3771 kW
Power170,377.1082 W
Torque300 lb-ft
Torque406.7454 N-m
Rotational speed4,000 rpm
  • Mechanical horsepower is used.
  • Torque and RPM describe the same shaft and same operating point.
  • The calculator is educational and does not certify motor, machine, vehicle, or safety ratings.
  • Intermediate values are not rounded; raw outputs are rounded to 10 decimals for stability.

Accuracy notes

Risk level
B
Reviewed
2026-05-26
Sources
3
Primary result
Horsepower

Formula logic is kept in a pure calculator module with fixtures, source notes, and page-visible assumptions.

Categories

What the result means

Use Horsepower as the headline answer for horsepower. Mechanical horsepower. Read the converted value first, then verify the source unit, target unit, and factor before reusing the number. Use power, torque, and rotational speed to explain why horsepower moved when an input changed. Keep the original value next to the converted value when using it in a workflow. Check source unit, target unit, dimension compatibility, exchange or conversion rate, and rounding precision before treating the result as final.

HorsepowerMechanical horsepower.
PowerPower in kilowatts.
PowerPower in watts.
TorqueTorque normalized to pound-foot.

Use the result this way

  1. Start with Horsepower, then use supporting outputs only to explain the primary answer.
  2. Verify solve for, torque, and torque unit before copying the result.
  3. Choose the mode or method first because it can change which formula is applied, keep units consistent with the labels shown in the form, and stay within the documented minimum and maximum ranges.
  4. Keep the original value next to the converted value when using it in a workflow.

User job

How to use this calculator

Use Horsepower Calculator when you need horsepower, then use power and power to check the context for unit checks, engineering notes, recipes, travel, shopping, and measurement cleanup.

Best for

  • Converting compatible units
  • Auditing the factor used for a repeated conversion
  • Reviewing a default example before entering your own solve for and torque.

Check before relying

  • Make sure the source and target units measure the same kind of quantity.
  • Mechanical horsepower is used.
  • Torque and RPM describe the same shaft and same operating point.
  • Source context: National Institute of Standards and Technology, reviewed 2026-05-26.

Next useful step

Formula

Power in watts is torque in N-m multiplied by angular speed in radians per second. Mechanical horsepower is watts divided by 745.699871582. Key assumptions: Mechanical horsepower is used. Torque and RPM describe the same shaft and same operating point. The calculator is educational and does not certify motor, machine, vehicle, or safety ratings.

  • Power in watts is torque in N-m multiplied by angular speed in radians per second. Mechanical horsepower is watts divided by 745.699871582.
  • Mechanical horsepower is used.
  • Torque and RPM describe the same shaft and same operating point.
  • Primary source context: National Institute of Standards and Technology.

Inputs

Enter solve for, torque, torque unit, and rotational speed for unit checks, engineering notes, recipes, travel, and measurement cleanup. Before calculating, choose the mode or method first because it can change which formula is applied, keep units consistent with the labels shown in the form, and stay within the documented minimum and maximum ranges. Solve for: Choose the unknown value in rotational power. Torque: Known torque. Required unless solving for torque. Torque unit: Unit for the torque input. Rotational speed: Known rotational speed. Required unless solving for RPM.

Solve forChoose the unknown value in rotational power.
TorqueKnown torque. Required unless solving for torque.
Torque unitUnit for the torque input.
Rotational speedKnown rotational speed. Required unless solving for RPM.
HorsepowerKnown mechanical horsepower. Required unless solving for horsepower.

Example

Using the default inputs, Horsepower Calculator returns horsepower of 228.4795 hp. Adjust solve for, torque, torque unit, and rotational speed to match your own scenario.

FAQ

How is horsepower calculated here?

Power in watts is torque in N-m multiplied by angular speed in radians per second. Mechanical horsepower is watts divided by 745.699871582. The first assumption to check is: Mechanical horsepower is used.

What does Horsepower mean for horsepower?

Read the converted value first, then verify the source unit, target unit, and factor before reusing the number. Secondary values such as power, torque, and rotational speed are there to explain the primary answer, not to replace it.

What should I enter for Solve for?

Choose the unknown value in rotational power. Choose the mode or method first because it can change which formula is applied, keep units consistent with the labels shown in the form, and stay within the documented minimum and maximum ranges.

How does Torque change horsepower?

Known torque. Required unless solving for torque. Changing it can alter horsepower because the formula uses the submitted inputs together. Also compare source unit, target unit, dimension compatibility, exchange or conversion rate, and rounding precision.

Why does the horsepower example show 228.4795 hp for horsepower?

The default inputs produce 228.4795 hp for horsepower. Treat that as a format and scale check, then replace every default value with your own inputs.

How do I avoid a horsepower unit-direction mistake?

Keep the original value beside the converted value, confirm both units measure the same quantity, and check whether rounding is acceptable for the task.

Sources

Last reviewed: 2026-05-26

  • Reviewed 2026-05-26
    NIST Guide to the SI, Appendix B.8: Factors for Units Listed AlphabeticallyNational Institute of Standards and Technology. Mechanical horsepower to watt, pound-force, foot, newton, meter, and revolutions-per-minute conversion context.
    Scope
    Unit conversion factors.
    Supports
    Mechanical horsepower to watt, pound-force, foot, newton, meter, and revolutions-per-minute conversion context.
  • Reviewed 2026-05-26
    NIST Guide to the SI, Chapter 8: Rules and Style ConventionsNational Institute of Standards and Technology. Use of watt and SI-compatible unit expression for source-backed output labels.
    Scope
    SI expression and unit usage guidance.
    Supports
    Use of watt and SI-compatible unit expression for source-backed output labels.
  • Reviewed 2026-05-26
    OpenStax University Physics Volume 1 - Rotational Kinetic EnergyOpenStax. Power equals torque multiplied by angular velocity for rotational motion.
    Scope
    Physics textbook derivation of rotational work and power.
    Supports
    Power equals torque multiplied by angular velocity for rotational motion.

Disclaimer

This calculator is an educational estimate based on the inputs and assumptions shown on the page.