Hohmann Transfer Calculator (Travel Time to Mars and Other Planets)
How long does it take to get to Mars, Venus or Jupiter? Compute the Hohmann transfer time, heliocentric delta-v, launch phase angle and launch-window interval between any two planets.
How it works
a_t = (r₁ + r₂) ÷ 2 · transfer time t = π √(a_t³ ÷ μ☉), μ☉ = 1.32712 × 10²⁰ m³/s² · Δv₁ = √(μ/r₁) (√(2r₂/(r₁+r₂)) − 1) · Δv₂ = √(μ/r₂) (1 − √(2r₁/(r₁+r₂))) · phase angle = 180° × [1 − ((r₁+r₂)/(2r₂))^1.5] · synodic period = 1 ÷ |1/T₁ − 1/T₂|
A Hohmann transfer is the most fuel-efficient two-burn path between two circular, coplanar orbits: half of an ellipse that touches the inner orbit at its closest point and the outer orbit at its farthest. Its duration is half the period of that ellipse, from Kepler’s third law. Planets’ orbits are treated as circles at their mean distances, and the Δv values are relative to the Sun — they leave out escaping Earth’s gravity and being captured at the destination. Launches must wait until the planets have the right phase angle, which recurs every synodic period (about 26 months for Mars).
Worked example
Earth (1.000 AU) to Mars (1.524 AU): a_t = 1.262 AU, so t = π √(a_t³ ÷ μ) = 259 days (8.5 months). The departure burn is 2.94 km/s and the arrival burn 2.65 km/s (5.59 km/s in total, relative to the Sun). Mars must be 44.3° ahead of Earth at launch, which happens every 780 days.
Sources: NASA JPL — Basics of Space Flight, chapter 4: Interplanetary trajectories · NASA — Planetary fact sheet (mean orbital distances)
Frequently asked questions
How long does it take to get to Mars?
About 259 days (8.5 months) on a minimum-energy Hohmann transfer. Real missions take roughly 6–9 months; NASA’s Perseverance took 203 days on a faster, more energetic path.
How long would it take to reach Jupiter or Neptune?
A Hohmann transfer to Jupiter takes about 2.7 years and to Neptune about 30.7 years. Real probes use gravity assists to arrive much sooner — Voyager 2 reached Neptune in 12 years.
Why can we only launch to Mars every 26 months?
Mars must be about 44° ahead of Earth when the spacecraft leaves so that both arrive at the meeting point together. That geometry repeats every synodic period, about 780 days.
Does the delta-v include leaving Earth?
No. These are heliocentric burns. Departing from low Earth orbit needs about 3.6 km/s for Mars because the Oberth effect lets the rocket gain the 2.94 km/s excess speed while still deep in Earth’s gravity well.
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This calculator is for educational purposes. Double-check important results before acting on them.