Launch Vehicle Selection Calculator

Payload capacity comparison across launch providers.

Inputs

Payload mass (kg)

Required delta-v (km/s)

Specific impulse (sec)

Dry mass fraction (%)

Cost per kg to orbit ($)

Tab to move between fields

Results

Propellant mass (kg)

104,021

Total launch mass (kg)

120,579

Launch cost ($M)

13.6

Mass ratio (m₀/m_f)21.8

Structural mass (kg)11,558

Payload fraction (%)4.15

Propellant fraction (%)86.27

Exhaust velocity (km/s)3.05

How to Use This Calculator

Enter payload mass (kg) and required delta-V (km/s) for your target orbit.
Set propellant specific impulse (sec) and dry mass fraction (%) for the launch vehicle stage.
Enter cost per kg to orbit ($) for the candidate launch vehicle.
Review mass ratio, propellant mass, structural mass, total launch mass, and payload fraction.
Compare payload fraction across launch vehicle options to identify the most mass-efficient choice.

How the result changes with Specific impulse (sec)

Specific impulse (sec)	Propellant mass (kg)	Total launch mass (kg)	Launch cost ($M)
590	20,383	27,648	13.6
1,815	3,479	8,865	13.6
3,285	1,694	6,882	13.6
4,510	1,184	6,316	13.6

What each input means

Payload mass (kg): Mass of the payload to be delivered to the target orbit.
Required delta-v (km/s): Total velocity change needed. LEO ~9.4, GTO ~12, Moon ~15.9, Mars ~16.5 km/s from surface.
Specific impulse (sec): Engine Isp. RP-1/LOX ~311s, LH2/LOX ~450s, ion ~3000s, solid ~260s.
Dry mass fraction (%): Structural mass as percentage of (structure + propellant). Modern rockets: 5-12%.
Cost per kg to orbit ($): Launch cost per kg of payload. Falcon 9: ~$2,720/kg, Atlas V: ~$13,200/kg, Electron: ~$26,000/kg.

What each result means

Mass ratio (m₀/m_f): Tsiolkovsky mass ratio: initial mass / final mass.
Propellant mass (kg): Required propellant mass from the rocket equation.
Structural mass (kg): Rocket dry structure mass (tanks, engines, fairings).
Total launch mass (kg): Payload + propellant + structure.
Payload fraction (%): Payload as percentage of total launch mass.
Propellant fraction (%): Propellant as percentage of total launch mass.
Exhaust velocity (km/s): Effective exhaust velocity = Isp x g₀.
Launch cost ($M): Estimated launch cost in millions of dollars.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Payload mass (kg) = 5000, Required delta-v (km/s) = 9.4, Specific impulse (sec) = 311, Dry mass fraction (%) = 10 = 5 input(s) provided
Calculate Propellant mass
Propellant mass = m_initial - m_final
104021 = 104021
Calculate Total launch mass
Total launch mass = payloadMassKg + propellantMassKg + structuralMassKg
120579 = 120579
Calculate Launch cost
Launch cost = (payloadMassKg * costPerKgUSD) / 1_000_000
13.6 = 13.6
Calculate Mass ratio
21.804 = 21.804
Calculate Structural mass
Structural mass = (propellantMassKg / (1 - dryFraction)) * dryFraction
11558 = 11558

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