Rocket Equation Calculator

Calculate delta-v using the Tsiolkovsky rocket equation for spacecraft and rocket design

Tsiolkovsky Rocket Equation

Total mass including rocket and propellant

kg

Dry mass after propellant is consumed

Speed of exhaust gases relative to rocket

Rocket Performance Results

4.828 km/s
Delta-V (Δv)
Change in velocity
5.00
Mass Ratio
m₀/mf ratio
80.0 t
Propellant Mass
80.0%
Propellant Fraction
306 s
Effective Isp

Formula: Δv = ve × ln(m₀/mf)

Effective Exhaust Velocity: 3.00 km/s

Performance Analysis

✓ Capable of reaching low Earth orbit (LEO requires ~9.4 km/s)

Historical Rocket Examples

Saturn V First Stage

Mass Ratio: 3.5

3.76 km/s
Delta-V

Saturn V Second Stage

Mass Ratio: 5

4.83 km/s
Delta-V

Saturn V Third Stage

Mass Ratio: 4.8

4.71 km/s
Delta-V

Space Shuttle Main Tank

Mass Ratio: 8

6.24 km/s
Delta-V

Falcon 9 First Stage

Mass Ratio: 3.3

3.58 km/s
Delta-V

Equation Components

Delta-V (Δv)

Change in velocity achieved by the rocket

Exhaust Velocity (ve)

Speed of propellant ejection relative to rocket

Mass Ratio (m₀/mf)

Ratio of initial mass to final mass

Specific Impulse (Isp)

Engine efficiency: ve = Isp × g₀

Typical Rocket Values

Chemical Rockets

Isp: 200-450s, ve: 2-4.5 km/s

Ion Drives

Isp: 3000-10000s, ve: 30-100 km/s

Solid Fuel

Isp: 180-250s, ve: 1.8-2.5 km/s

Liquid Fuel

Isp: 300-450s, ve: 3-4.5 km/s

Key Formulas

Rocket Equation

Δv = ve × ln(m₀/mf)

Exhaust Velocity

ve = Isp × g₀

Mass Ratio

R = m₀/mf = e^(Δv/ve)

Propellant Fraction

pf = (m₀-mf)/m₀

Understanding the Tsiolkovsky Rocket Equation

What is the Rocket Equation?

The Tsiolkovsky rocket equation, also known as the ideal rocket equation, describes the fundamental relationship between a rocket's mass, exhaust velocity, and the velocity change it can achieve. It's the cornerstone of astronautics and rocket design.

Key Principles

  • Conservation of momentum drives rocket motion
  • Higher exhaust velocity = better performance
  • Exponential relationship between mass ratio and delta-v
  • No external forces assumed (ideal vacuum)

Applications & Limitations

Applications

  • • Spacecraft mission planning
  • • Rocket stage optimization
  • • Propulsion system comparison
  • • Orbital maneuver calculations

Limitations

  • • Ignores gravity losses
  • • Ignores atmospheric drag
  • • Assumes constant exhaust velocity
  • • Ideal vacuum conditions only

Note: Real rockets need 30-50% more delta-v than theoretical due to gravity losses, drag, and steering losses.