Hohmann Transfer Calculator

It is the most fuel-efficient two-burn manoeuvre between two coplanar circular orbits. The first burn stretches the orbit into an ellipse that just touches the target radius, and the second burn at the far side circularises it.

With mu = G times M and semi-major axis a = (r1 + r2) / 2, the circular speeds are sqrt(mu/r1) and sqrt(mu/r2) and the ellipse speeds come from the vis-viva equation sqrt(mu times (2/r - 1/a)). Each burn is the difference between the circular and ellipse speed at that radius.

It uses the Newtonian gravitational constant G = 6.674e-11 N m^2/kg^2. Multiplying by your central mass gives the standard gravitational parameter mu that drives every speed in the calculation.

Radius, measured from the centre of the central body. For a 300 km Earth orbit you add Earth's radius of about 6.371e6 m to get roughly 6.671e6 m, which is why the LEO preset uses that figure.

It is half the orbital period of the transfer ellipse, t = pi times sqrt(a^3 / mu), the coast time from the departure burn to the arrival burn. For LEO to GEO that is about 18987 seconds, near 5.27 hours.

Departing low Earth orbit onto the ellipse costs about 2427.68 m/s and circularising at geostationary radius adds about 1467.51 m/s, for a total near 3895.19 m/s, or 3.9 km/s.

Not for the total. Swapping radius 1 and radius 2 swaps which burn is larger and reverses the direction, but the sum of the two delta-v values and the transfer time are identical because the ellipse is the same.

It assumes ideal instantaneous burns between perfectly circular, coplanar orbits around a single point mass. It ignores plane changes, orbital eccentricity, atmospheric drag, finite burn duration and the gravity of other bodies, so treat it as an ideal lower bound on the budget.

No. Every number is computed locally in your browser, so your mission parameters stay on your own device.