Ideal Rocket Equation Calculator
Calculate ideal delta-v, propellant fraction and mass ratio from initial mass, final mass and effective exhaust velocity.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Convert both masses and effective exhaust velocity to consistent units, form the initial-to-final mass ratio and apply the natural logarithm in the ideal rocket equation.
Δv=vₑ ln(m₀/mf)
Worked example
Initial mass 10,000 kg, final mass 4,000 kg and effective exhaust velocity 3,000 m/s give mass ratio 2.5 and ideal delta-v about 2,748.87 m/s.
Assumptions and input details
Initial and final masses must be positive and initial mass must exceed final mass. Effective exhaust velocity is entered directly and must be positive. The ideal equation assumes one equivalent exhaust velocity and no gravity, drag, steering, pressure variation, staging interaction, residual propellant or finite-burn trajectory loss. It does not establish vehicle performance or mission feasibility.
References: NASA Glenn Research Center: Ideal Rocket Equation
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
The 19 mass definitions distinguish avoirdupois and troy measures, metric and regional measures. Japanese kin is 600 g; mainland Chinese shijin is 500 g.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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