Delta-V Budget Calculator
Add up the velocity changes of every leg of a mission, apply a margin, and turn the total into propellant for a given dry mass and engine — the delta-v budget that every mission plan starts from.
Each manoeuvre — launch, transfer, capture, landing — costs a velocity change, and they add.
How the delta-v budget calculator works
Each manoeuvre — launch, transfer, capture, landing — costs a velocity change, and they add. A margin of a few per cent covers navigation errors and off-nominal burns. The total then goes into the rocket equation with the engine's specific impulse and the vehicle's dry mass to give the propellant, which is usually most of the vehicle.
The legs' shares show where the budget goes, and the largest is the one worth attacking with a gravity assist or aerobraking.
Formula: Δv_total = (1 + margin) Σ Δvᵢ; propellant = m_dry (e^(Δv / (Isp g₀)) − 1)
Worked examples
| Inputs | Total delta-v with margin (m/s) | Note |
|---|---|---|
| Launch, escape, capture, landing | 15,435 | launch dominates |
| From orbit only | 5,565 | far less propellant |
| A hydrogen stage | 5,565 | less again |
FAQFrequently asked questions
What is a delta-v budget?
The list of every velocity change a mission needs, summed with a margin. It is the currency of mission design: every kilogram of payload is paid for in delta-v.
Why do the legs simply add?
Because each burn changes velocity by its own amount, and the rocket equation is exponential in the total — which is also why the order of burns does not change the propellant.
What margin is typical?
Three to ten per cent for navigation, gravity losses and contingencies. Crewed missions and long cruises sit at the top of the range.
Where do the numbers come from?
Launch to low Earth orbit about 9.4 km/s; escape from there about 3.2; Mars capture roughly 0.9 to 2; a powered landing 0.5 to 1.5. The Hohmann page gives orbit-to-orbit legs.
How do missions cut the budget?
Gravity assists, aerobraking on arrival, and staging so that empty tanks are not carried. The largest leg is where a few hundred metres per second saved matters most.
Where these figures come from
- NIST — CODATA 2018 fundamental physical constants — G and the speed of light
- IAU 2015 Resolution B3 — nominal solar and planetary conversion constants — the astronomical unit, solar mass and planetary radii
- CSIRO Space and Astronomy — Australia's national science agency
Last checked: September 2026. Constants are CODATA 2018 (G, c) and IAU 2015 nominal values (solar and planetary parameters).