🔧 Engine Horsepower Calculator
A typical naturally aspirated engine makes roughly one horsepower per 15 cc of displacement. This estimator applies that rule to your engine's size for a quick ballpark figure.
Treat it as a rough estimate only: turbocharging, tuning, fuel and engine design move real output far from the rule of thumb.
How to use this calculator
Enter your engine's displacement in cc and get a rough horsepower ballpark from the one-HP-per-15cc rule of thumb.
- Find your engine's displacement in cc from the manual or badge.
- Enter the Displacement value.
- Optionally set the cylinder count for reference.
- Read the estimated horsepower and the basis of the estimate.
Frequently asked questions
How is the horsepower estimated?
The calculator divides displacement in cc by 15, the rough rule that a typical naturally aspirated engine makes about one horsepower per 15 cc.
Can you give a worked example?
A 2000 cc engine estimates to about 133.3 horsepower.
How accurate is this?
It is a ballpark, not a measurement. Turbocharging, tuning, fuel quality and engine design move real output far from the rule of thumb.
What gives the true number?
A dynamometer run measures actual wheel or crank horsepower. Use this estimate only for casual comparison.