Delta-V Calculator

The Currency of Spaceflight Mission Planning

Mission planners don't budget spacecraft trajectories in fuel mass or burn time — they budget in delta-v, the total velocity change a vehicle can deliver across every maneuver of its mission. A Mars mission profile, for example, is planned as a sequence of delta-v requirements (launch, trans-Mars injection, orbit insertion, landing) added together, then checked against what the vehicle's engine and propellant load can actually supply.

The Formula

This is the same Tsiolkovsky relationship used for a single-burn delta-v figure, applied here with an explicit propellant mass readout — useful when the question is "how much propellant does this maneuver cost" rather than just the resulting velocity change.

Where This Calculation Matters

• Total mission budgeting — summing delta-v requirements across every planned maneuver, from launch to final orbit, against the vehicle's total delta-v capacity.
• Propellant margin analysis — converting a delta-v requirement into a propellant mass shows exactly how much margin (or shortfall) exists in the tank budget.
• Trajectory tradeoffs — comparing delta-v cost between a direct transfer and a more fuel-efficient but slower gravity-assist trajectory.
• Station-keeping planning — satellites budget a delta-v allowance for years of small orbit-maintenance burns, which this same formula scales down to compute.

Delta-v and Propellant Cost by Mass Fraction

How to Use This Calculator

1. Enter the specific impulse (Isp) of the propulsion system in seconds.
2. Enter the initial (wet) mass in kilograms.
3. Enter the final (dry) mass in kilograms.
4. Select Calculate to get the delta-v and the propellant mass consumed.

Related Calculations

Compute the required orbital velocity target with the Orbital Insertion Velocity Calculator, or double-check the underlying Isp with the Specific Impulse Calculator.