Inputs
Formulas
Δv = ve ln(m0 / mf)
ve = Isp · g₀
R = m0 / mf = eΔv / ve
mp = m0 − mf = mf(R − 1)
ve = Isp · g₀
R = m0 / mf = eΔv / ve
mp = m0 − mf = mf(R − 1)
All computations use natural logarithms and SI units internally. Ensure masses are in the same unit.
Results
Enter inputs and click Compute to see results.
Tips
- Use Isp in seconds for convenience or ve directly for theoretical studies.
- Switch Δv between m/s and km/s to match mission needs.
- mf should include structure and payload for single stage estimates.
- Results assume constant Isp and no gravity or drag losses.
Frequently Asked Questions
What does the Tsiolkovsky equation calculate?
It relates achievable delta v to exhaust velocity and the ratio of initial to final mass. It is the core sizing relation for rockets under idealized conditions.
Should I enter Isp or effective exhaust velocity?
Enter either. If you provide Isp in seconds the tool multiplies by g₀ to get exhaust velocity. If you already know ve you can input it directly.
Do these results include gravity or atmospheric losses?
No. They are ideal vacuum values. Real missions require additional delta v margins to cover gravity drag steering and ascent profile losses.
What is mass ratio?
It is m0 divided by mf. A higher mass ratio means more propellant relative to dry mass and enables larger delta v for a given exhaust velocity.
Can I model multiple stages?
This single page focuses on one stage. For multi stage vehicles compute each stage separately then sum the stage delta v to get the total ideal value.