Rocket Burn Time Calculator

About this calculator

A rocket engine’s burn time is simply its total propellant mass divided by its mass flow rate — the rate at which the engine consumes propellant, usually expressed in kilograms or pounds per second. A larger mass flow rate produces more thrust but empties the propellant tanks faster, so burn time is one of the core trade-offs engineers balance against thrust and specific impulse when sizing an engine for a given mission.

Aerospace engineers and propulsion designers use burn time calculations when selecting or designing a motor for a given vehicle, since it determines how long an engine can accelerate a rocket before staging or shutdown, and model rocketry hobbyists use the same math, scaled down, to match motor selection to a rocket’s flight profile and to predict apogee. It’s a foundational calculation that feeds directly into the rocket equation for estimating achievable velocity change (delta-v).

This calculator takes your total propellant mass and mass flow rate and returns how long the engine will burn before running out of propellant.