Donaldson R F Hohmann Transfer Delta-v Calculator
The cheapest way between two circular orbits: two burns, one coasting ellipse. Pick a body and two altitudes.
How this is worked out
A Hohmann transfer moves a spacecraft between two circular orbits around the same body using the least propellant possible, with exactly two instantaneous burns and an elliptical coasting orbit in between whose perigee touches the lower orbit and apogee touches the higher one. Each burn's size comes from the vis-viva equation, v² = GM(2/r − 1/a), applied once on the circular orbit and once on the transfer ellipse at the same point: the first burn raises (or lowers) the spacecraft onto the transfer ellipse, and the second circularises it at the target orbit. This is the idealised, two-body, coplanar, impulsive-burn case — a real mission also has to match the target orbit's plane (a separate, often costly manoeuvre not included here) and burns take a little time rather than being instant.
Frequently asked questions
Is a Hohmann transfer always the best choice?
It's the lowest-delta-v option between two circular orbits when there's no rush, but it's also the slowest practical option (half an orbit of the transfer ellipse) — faster transfers exist, they just cost more delta-v.
Why two separate burns?
The first burn only changes the spacecraft's speed at its current altitude, stretching the orbit into an ellipse reaching the new altitude; the spacecraft is still moving too fast (or slow) for a circular orbit when it gets there, so a second burn is needed to circularise it.
Related tools: Orbital & Escape Velocity Calculator, Kepler's Third Law Calculator, Rocket Equation Calculator.
Source / Last verified: the vis-viva equation is classical two-body orbital mechanics (a direct consequence of conservation of energy for a Keplerian orbit), the same textbook framework already used by this site's Orbital & Escape Velocity Calculator. The gravitational constant G = 6.674 30 × 10&supminus;¹&sup9; m³kg&supminus;¹s&supminus;² is the CODATA 2022 value (NIST, physics.nist.gov). Body masses and radii are from NASA/GSFC, "Planetary Fact Sheet – Metric" (nssdc.gsfc.nasa.gov/planetary/factsheet). All read 1 October 2026. The default 300 km → 35,786 km (geostationary altitude) Earth example reproduces the commonly-quoted figures for this transfer: about 2.4 km/s + 1.5 km/s = 3.9 km/s total, over roughly 5h17m.