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Delta V Budget Calculator

Calculate the total delta-v budget needed for a space mission between two bodies. Enter values for instant results with step-by-step formulas.

Reviewed by Daniel Agrici, Founder & Lead Developer

Reviewed by Daniel Agrici, Founder & Lead Developer

Formula

Delta-v = Ve x ln(m0 / mf) = Isp x g0 x ln(m0 / mf)

The Tsiolkovsky rocket equation gives the maximum velocity change (delta-v) a rocket can achieve. Ve is the effective exhaust velocity, m0 is the initial wet mass, mf is the final dry mass, Isp is the specific impulse, and g0 is standard gravity (9.80665 m/s^2).

Worked Examples

Example 1: GEO Satellite Mission

Problem:A 2,000 kg satellite with 4,500 kg propellant and an engine with 321s Isp. Can it reach GEO from LEO?

Solution:Effective Ve = 321 x 9.80665 = 3,147.9 m/s\nInitial mass = 2,000 + 4,500 = 6,500 kg\nMass ratio = 6,500 / 2,000 = 3.25\nDelta-v = 3,147.9 x ln(3.25) = 3,147.9 x 1.1787 = 3,711 m/s\n\nRequired: LEO-GTO (2,440) + GTO-GEO (1,470) = 3,910 m/s\nMargin = 3,711 - 3,910 = -199 m/s (insufficient!)

Result:Available: 3,711 m/s | Required: 3,910 m/s | Shortfall: 199 m/s

Example 2: Lunar Mission Budget

Problem:A 5,000 kg spacecraft with 15,000 kg propellant and 316s Isp. Budget for LEO to Lunar orbit.

Solution:Effective Ve = 316 x 9.80665 = 3,098.9 m/s\nMass ratio = 20,000 / 5,000 = 4.0\nDelta-v = 3,098.9 x ln(4.0) = 3,098.9 x 1.3863 = 4,295 m/s\n\nRequired: LEO to Lunar Orbit = 3,900 m/s\nMargin = 4,295 - 3,900 = 395 m/s (10.1% margin)\nPropellant fraction = 75%

Result:Available: 4,295 m/s | Required: 3,900 m/s | Margin: 395 m/s (10.1%)

Frequently Asked Questions

What is delta-v and why is it important for space missions?

Delta-v (change in velocity) is the fundamental measure of a spacecraft's capability to perform maneuvers in space. It represents the total amount of velocity change a rocket can produce from its propulsion system. Every orbital maneuver, from launching to orbit, transferring between orbits, and landing on other bodies, requires a specific amount of delta-v. Mission planners create a delta-v budget that lists all required maneuvers and their costs, then ensure the spacecraft carries enough propellant to achieve the total. If a spacecraft's available delta-v exceeds the mission requirement, the mission is feasible. Insufficient delta-v means the spacecraft cannot complete its planned trajectory.

What are typical delta-v requirements for common space missions?

Delta-v requirements vary significantly by destination. Reaching Low Earth Orbit from the surface requires about 9,400 m/s including gravity and drag losses. From LEO, a transfer to geostationary orbit needs about 3,900 m/s. A lunar transfer from LEO costs about 3,900 m/s, with lunar orbit insertion adding 800 m/s and landing requiring another 1,700 m/s. A Mars transfer from LEO needs roughly 3,600 m/s, with Mars orbit capture adding 900 m/s. Interplanetary missions to Jupiter require about 6,300 m/s from LEO. These costs can be reduced using gravity assists from planets, which is why missions like Voyager used flybys.

References

Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy