MyCalcul LogoMyCalcul

Horsepower Calculator

Calculate engine horsepower from torque and RPM.

Engineering
Horsepower Calculator
Calculate engine horsepower from torque and RPM.

Advertisement

Related Calculators

Ohm's Law Calculator
Calculate voltage, current, resistance, and power using Ohm's Law.
Concrete Calculator
Estimate the amount of concrete needed for a project.
Resistor Color Code Calculator
Determine the resistance value from resistor color bands.
Voltage Divider Calculator
Calculate output voltage in a voltage divider circuit.

Advertisement

Understanding Engine Performance

This calculator determines an engine's horsepower (HP) using the standard industry formula. It relates torque (the rotational force of the engine) and engine speed (RPM). It's a fundamental tool for auto enthusiasts, mechanics, and mechanical engineers to understand engine performance.

The Horsepower Formula Explained

Horsepower is a measure of the rate at which work is done. The formula used is: Horsepower (HP) = (Torque (lb-ft) × RPM) / 5252

  • Torque: The twisting force of the engine, measured in pound-feet (lb-ft).
  • RPM: Revolutions Per Minute, the speed at which the engine's crankshaft is spinning.
  • 5252: A constant that makes the units compatible. It comes from the conversion of torque and RPM into horsepower (1 HP = 33,000 ft-lb/min).

How to Use the Calculator

  1. Torque (lb-ft): Enter the engine's torque value.
  2. RPM: Enter the engine speed at which that torque was measured.
  3. Calculate: The tool will display the calculated horsepower.

Real-World Example

An engine produces 350 lb-ft of torque at 4,500 RPM.

  • Calculation: (350 * 4500) / 5252 ≈ 299.8 HP
  • The engine is producing approximately 300 horsepower at that specific RPM.

Frequently Asked Questions (FAQ)

  • Why do torque and horsepower curves always cross at 5252 RPM? Because of the constant in the formula. At 5252 RPM, the(RPM) / 5252 part of the equation equals 1, so Horsepower = Torque. Below 5252 RPM, torque is always numerically higher than horsepower; above it, horsepower is always higher.
  • What's more important, torque or horsepower? It depends on the application. Torque is the raw twisting force that gets a vehicle moving (important for towing and acceleration from a stop). Horsepower is the rate at which that work can be done, which relates to top speed and high-speed acceleration.
  • Can I use different units? This calculator is specifically for torque in lb-ft. If you have torque in another unit like Newton-meters (N·m), you must first convert it to lb-ft (1 N·m ≈ 0.737 lb-ft).