Turbo Boost Horsepower Gain Calculator

About this calculator

A rough estimate of boosted horsepower from a naturally aspirated baseline uses the ratio of absolute pressure with boost to atmospheric pressure alone: boosted HP ≈ naturally aspirated HP × (atmospheric pressure + boost pressure) ÷ atmospheric pressure — so, using standard sea-level atmospheric pressure of roughly 14.7 psi, 7 psi of boost theoretically adds about 48% more air (and therefore roughly 48% more potential power) before accounting for real-world losses.

Car tuners and enthusiasts use this calculation as a starting estimate when planning a turbo or supercharger install, understanding that the real-world gain typically falls short of the theoretical figure because of intercooler efficiency losses, fuel system limits, ignition timing constraints and the engine's mechanical ability to handle the added cylinder pressure — the calculation gives a ceiling to plan around, not a guaranteed dyno number.

This calculator takes your naturally aspirated horsepower and boost pressure, and returns the estimated boosted power and the horsepower gain.