# Horsepower Calculator

Calculate horsepower from torque and RPM using the standard formula HP = (Torque x RPM) / 5252. Also solve for torque or RPM and convert HP to kilowatts.

## What this calculates

Calculate engine horsepower from torque and RPM, or work backward to find torque or RPM from a known HP figure. This calculator uses the standard mechanical horsepower formula and includes a kilowatt conversion for international comparisons.

## Inputs

- **Solve For** — options: Horsepower (from torque & RPM), Torque (from HP & RPM), RPM (from HP & torque) — Choose which value to calculate
- **Torque** (lb-ft) — min 0, max 50000 — Torque (used when solving for HP or RPM)
- **RPM** — min 0, max 30000 — Engine revolutions per minute (used when solving for HP or torque)
- **Horsepower** (HP) — min 0, max 10000 — Horsepower value (used when solving for torque or RPM)

## Outputs

- **Horsepower** — Mechanical (brake) horsepower
- **Torque** (lb-ft) — Output torque
- **Power in Kilowatts** — Equivalent power in kilowatts (1 HP = 0.7457 kW)

## Details

The fundamental relationship between horsepower, torque, and RPM is: HP = (Torque in lb-ft x RPM) / 5252. The constant 5252 comes from the definition of one horsepower (33,000 ft-lbs of work per minute) divided by 2π. At exactly 5,252 RPM, horsepower and torque are equal.

This formula applies to mechanical (brake) horsepower as measured at the crankshaft or wheels. Wheel horsepower is typically 15-20% less than crank horsepower due to drivetrain losses. Dynamometer (dyno) results usually report both.

The kilowatt conversion (1 HP = 0.7457 kW) is used in most countries outside the US. Electric vehicles are commonly rated in kW, while combustion engines in the US market still use horsepower.

## Frequently Asked Questions

**Q: Where does the 5252 constant come from?**

A: One mechanical horsepower is defined as 33,000 foot-pounds of work per minute. Since torque is a rotational force, the formula includes 2π to convert revolutions to linear distance. 33,000 / (2 × π) = 5,252.11, rounded to 5,252.

**Q: What is the difference between HP and torque?**

A: Torque is the rotational force the engine produces, measured in pound-feet. Horsepower is the rate at which that force does work (power = force x speed). Think of torque as the strength and horsepower as how fast that strength is applied.

**Q: What is the difference between crank HP and wheel HP?**

A: Crank (brake) horsepower is measured at the engine output shaft. Wheel horsepower is measured at the wheels and is typically 15-20% lower due to losses in the transmission, differential, and driveline.

**Q: How many HP does a typical car have?**

A: A compact car typically has 130-180 HP, a mid-size sedan 180-250 HP, a sports car 300-500 HP, and a supercar 500+ HP. Trucks and SUVs commonly range from 250-400 HP depending on the engine.

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Source: https://vastcalc.com/calculators/everyday/horsepower
Category: Everyday Life
Last updated: 2026-04-21