Rocket Equation Calculator

Enter the exhaust velocity, initial mass, and final mass of a rocket to calculate the change in velocity of that rocket.

• Instantaneous Velocity Calculator
• Acceleration Calculator
• Orbital Speed Calculator

Rocket Equation Formula

The following equation is used by the calculator above to calculate the change of velocity of a rocket.

Δv = ev * ln(mi / mf)

• Where Δv is the change in velocity
• ev is the exhaust velocity
• mi is the initial mass
• mf is the final mass after all propellants have been burned.

Conceptually this formula can be described as the change of velocity being the difference between the initial and final velocity which are dependent on the masses and the escape velocity of the exhaust. In this case, the initial velocity is assumed to be 0 since the rocket has not launched yet.

Another important aspect in this equation to keep in mind is that since the velocity is dependent on the natural log of a ratio of masses, the masses should be the same units, but the units don’t affect the outcome.

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