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Brake Horsepower Calculator

Convert wheel HP to brake HP or calculate from torque and RPM.

Last updated: June 13, 2026

Calculator

Calculation Method

Wheel Horsepower (WHP)

Drivetrain

Results

Brake Horsepower (BHP)294 HP

Wheel Horsepower250 HP

Drivetrain Loss15%

~44 HP lost

How to Use This Calculator

1Select your calculation method: from dyno or from torque.
2For dyno method: enter wheel HP and drivetrain type.
3For torque method: enter torque and RPM.
4View brake horsepower and drivetrain loss.

Formula Explanation

BHP is the power measured at the engine crankshaft. Dyno readings at the wheels are reduced by drivetrain losses.

BHP = WHP ÷ (1 - Drivetrain Loss) or BHP = (Torque × RPM) ÷ 5252

Variables:

WHPWheel horsepower from a dyno test

Drivetrain Loss12% FWD, 15% RWD, 20% AWD typical losses

Torque/RPMFor direct calculation method

Worked Examples

250 WHP on RWD vehicle

1. BHP = 250 ÷ (1 - 0.15) = 250 ÷ 0.85

Result: BHP ≈ 294 HP (44 HP lost to drivetrain)

Why Use This Calculator

Understand true engine output from dyno results.
Accounts for drivetrain type.
Two calculation methods for flexibility.
Compare your car to factory BHP ratings.

336 × 280 Large Rectangle

300 × 250 Medium Rectangle

Tips & Best Practices

Dyno results vary between dynamometer types (inertia vs. load).
Temperature and altitude affect dyno readings.
Factory ratings are typically measured with SAE J1349 correction factors.

Common Mistakes to Avoid

❌ Comparing wheel HP between different drivetrain types.

✅ AWD cars show 20% less at the wheels. Convert to BHP for fair comparisons.

❌ Assuming all dynos read the same.

✅ Different dyno brands and types can show 5-10% variation. Compare results from the same dyno.

Frequently Asked Questions

What is the difference between BHP and WHP?

BHP (brake horsepower) is measured at the engine. WHP (wheel horsepower) is measured at the wheels after drivetrain losses. WHP is what actually moves the car.

Why does my car make less WHP than the factory BHP rating?

Factory BHP is at the engine. Your dyno reads at the wheels after 12-20% drivetrain losses. 250 WHP from a 300 BHP car is perfectly normal.

336 × 280 Large Rectangle

300 × 250 Medium Rectangle

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Disclaimer: This calculator is provided for informational and educational purposes only. Results are estimates and should not be used as a substitute for professional advice. RediCalc.com makes no guarantees regarding the accuracy, completeness, or suitability of any calculations. Always consult a qualified professional before making financial, health, construction, or other important decisions.

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