Orbital Transfer Delta-V Calculator
The Hohmann transfer is the minimum energy two-impulse maneuver for transferring between two coplanar circular orbits. This calculator uses NASA's standard gravitational parameter for Earth (mu = 398,600 km3/s2) and computes the delta-V for each burn, the total delta-V, the transfer orbit semi-major axis, and the transfer time. Enter orbit radii from the center of Earth (radius + altitude above Earth surface). Earth mean radius is 6,371 km.
Hohmann transfer delta-V formulas
v_c1 = sqrt(mu / r1) (circular speed at r1)
v_c2 = sqrt(mu / r2) (circular speed at r2)
a_transfer = (r1 + r2) / 2 (semi-major axis)
v_perigee = sqrt(mu x (2/r1 - 1/a)) (transfer perigee speed)
v_apogee = sqrt(mu x (2/r2 - 1/a)) (transfer apogee speed)
dV1 = |v_perigee - v_c1|
dV2 = |v_c2 - v_apogee|
t_transfer = pi x sqrt(a^3 / mu) (half period)
These formulas come from the vis-viva equation v^2 = mu x (2/r - 1/a), derived from conservation of energy and angular momentum. The gravitational parameter mu = 398,600 km3/s2 for Earth is the NASA standard value from the 2020 Astronomical Almanac.
Common orbital transfer examples
- LEO to GEO: r1 = 6,571 km (200 km altitude), r2 = 42,164 km. Total delta-V approximately 3.9 km/s.
- LEO to lunar orbit: requires approximately 3.1 km/s plus lunar orbit insertion.
- Earth to Mars Hohmann: approximately 2.9 km/s departure from Earth. Transfer time approximately 8.5 months.
- Deorbit burn from ISS (408 km): approximately 70-100 m/s retrograde delta-V to initiate reentry.
Orbital transfer delta-V calculator: frequently asked questions
What is a Hohmann transfer?
A Hohmann transfer is the most fuel-efficient two-burn maneuver for transferring a spacecraft between two coplanar circular orbits. The first burn raises (or lowers) the orbit to an elliptical transfer orbit. The second burn at the other apse circularizes the orbit at the target altitude. It was described by Walter Hohmann in 1925 and remains the basis for most orbital transfers.
What is delta-V?
Delta-V (delta-v) is the change in velocity required for a spacecraft maneuver. It is measured in metres per second and is the key currency of orbital mechanics: every maneuver costs delta-V, and the available delta-V is determined by propellant mass and specific impulse via the Tsiolkovsky rocket equation. Lower delta-V means less propellant required.
How is Hohmann transfer delta-V calculated?
For a Hohmann transfer from orbit r1 to orbit r2 around a central body of gravitational parameter mu: v1 = sqrt(mu/r1) is the circular orbit speed at r1. Transfer orbit perigee speed = sqrt(mu x (2/r1 - 1/(r1+r2)/2)). Delta-V1 = transfer perigee speed - v1. Delta-V2 is the similar calculation at the apogee. Total delta-V = |delta-V1| + |delta-V2|.
What is the gravitational parameter (mu)?
The gravitational parameter mu = G x M, where G is the gravitational constant (6.674e-11 m3/(kg x s2)) and M is the mass of the central body. For Earth, mu = 398,600 km3/s2 (NASA standard). For the Moon, mu = 4,904.87 km3/s2. For the Sun, mu = 1.327e11 km3/s2. Using mu directly avoids separately knowing G and M.
What is transfer time for a Hohmann orbit?
Transfer time = pi x sqrt(a^3 / mu), where a is the semi-major axis of the transfer ellipse = (r1 + r2) / 2. For a low Earth orbit to geostationary orbit transfer, a = (6,571 + 42,164) / 2 = 24,367 km. Transfer time = pi x sqrt(24,367^3 / 398,600) = approximately 5.25 hours (one half-period of the transfer ellipse).
Official sources
- NASA: Orbital Mechanics (NASA Small Spacecraft Technology).
- NASA Jet Propulsion Laboratory: Planetary Physical Parameters (JPL) - gravitational parameters.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.