Fuel Pump Flow Calculator

About this calculator

Fuel pump sizing starts from how much fuel an engine actually burns to produce power, expressed as BSFC (brake-specific fuel consumption), typically in lb of fuel per horsepower-hour. Required fuel flow is simply target horsepower multiplied by BSFC, giving a mass flow rate that the pump and injectors must be able to deliver.

Because pumps and fuel lines are usually rated in volume rather than mass, that mass flow is converted to a volumetric flow using the fuel's density (roughly 6.0–6.3 lb/gal for pump gasoline, lower for E85), producing figures in L/h, gal/h and lb/hr that tuners compare against a pump's rated flow at system pressure.

Engine builders and tuners use this to avoid fuel starvation under boost or high RPM — sizing the pump with margin above the calculated demand (commonly 20–30%) so injector duty cycle and pump output stay safely within limits at the target power level.