Calculate the efficiency of a rocket engine (Isp), its thrust, or propellant flow rate.
Input Parameters
Calculation Results
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About this calculator
Quick Reference
FThrust in Newtons
ṁMass flow rate in kg/s
g0Standard gravity (9.80665 m/s²)
veIsp * g0 (Exhaust Velocity)
Overview
Specific impulse (Isp) is a measure of how efficiently a rocket engine uses its propellant. It is defined as the thrust per unit mass flow rate of propellant.
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Pro Tips
Standard gravity (g0) is usually taken as 9.80665 m/s².
A higher specific impulse means more thrust is produced per kilogram of propellant.
Specific impulse is often expressed in seconds (unit of time).
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Fun Facts
"Liquid hydrogen/liquid oxygen engines usually have a vacuum Isp around 450 seconds."
"Ion thrusters have much higher specific impulses, potentially exceeding 3,000 seconds, but very low thrust."
"The Space Shuttle Main Engines had a sea-level Isp of about 366 seconds."
