Rocket Mass Ratio Calculator

Enter delta-v and specific impulse (Isp) to compute the required mass ratio and propellant fraction using the Tsiolkovsky rocket equation.

Inputs

Total velocity change required for the mission.

Engine efficiency. Kerosene/LOX ≈ 311 s; H₂/LOX ≈ 450 s.

If provided, calculates propellant and dry mass.

Mass Ratio (m₀ / m₁)

—

Initial mass ÷ Final (dry) mass

Propellant Mass Fraction

—

Fraction of initial mass that is propellant

Tsiolkovsky Rocket Equation

Δv = Isp × g₀ × ln(m₀ / m₁)

g₀ = 9.80665 m/s² (standard gravity)

Summary

Enter delta-v and specific impulse (Isp) to compute the required mass ratio and propellant fraction using the Tsiolkovsky rocket equation.

How it works

  1. Enter the required delta-v — the total velocity change needed for the mission.
  2. Enter the specific impulse (Isp) of the propellant/engine combination.
  3. Select units: delta-v in m/s or km/s; Isp in seconds.
  4. The calculator applies the Tsiolkovsky equation: mass ratio = e^(Δv / (Isp × g₀)).
  5. Results show the mass ratio, propellant mass fraction, and a breakdown for any chosen initial mass.

Use cases

  • Estimate propellant requirements for orbital maneuvers.
  • Compare engine types by plugging in different Isp values.
  • Determine whether a single-stage rocket design is feasible.
  • Verify delta-v budgets for mission planning.
  • Understand staging trade-offs by analyzing multi-burn mass ratios.
  • Teach or study the Tsiolkovsky rocket equation interactively.

Frequently Asked Questions

Last updated: 2026-06-15 · Reviewed by Nham Vu