Mars Launch Window Calculator
Find the next opportunity to launch from Earth to Mars using a Hohmann transfer orbit.
Opens Nov 18, 2026 · Optimal Dec 3, 2026
Until window opens
Next window — Hohmann transfer parameters
- Window opens
- Nov 18, 2026
- Optimal departure
- Dec 3, 2026
- Window closes
- Dec 18, 2026
- Estimated arrival
- Aug 19, 2027
- Transit time
- ~259 days (8.5 months)
- Next window after this
- ~26 months later
Next 8 Earth–Mars launch opportunities
| Optimal Departure | Window Open | Window Close | Arrival at Mars |
|---|---|---|---|
| Dec 3, 2026 Next | Nov 18, 2026 | Dec 18, 2026 | Aug 19, 2027 |
| Jan 6, 2029 | Dec 22, 2028 | Jan 21, 2029 | Sep 22, 2029 |
| Feb 8, 2031 | Jan 24, 2031 | Feb 23, 2031 | Oct 25, 2031 |
| Mar 18, 2033 | Mar 2, 2033 | Apr 2, 2033 | Dec 1, 2033 |
| May 9, 2035 | Apr 24, 2035 | May 24, 2035 | Jan 23, 2036 |
| Jul 26, 2037 | Jul 11, 2037 | Aug 10, 2037 | Apr 11, 2038 |
| Oct 5, 2039 | Sep 20, 2039 | Oct 20, 2039 | Jun 20, 2040 |
| Nov 19, 2041 | Nov 4, 2041 | Dec 4, 2041 | Aug 5, 2042 |
How It Works
A Hohmann transfer orbit is the most fuel-efficient path between two planets. It is an elliptical orbit whose perihelion (closest point to the Sun) is at Earth's orbit and whose aphelion (farthest point) is at Mars's orbit. A spacecraft follows this half-ellipse for approximately 259 days before arriving at Mars.
For this trajectory to work, Mars must already be at the arrival point when the spacecraft gets there — which only happens at specific times. These opportunities are called launch windows and recur roughly every 26 months (the synodic period: how long until Earth and Mars return to the same relative positions).
This calculator uses simplified Keplerian orbital elements from the NASA/JPL J2000 model to compute planetary positions. The windows shown are Hohmann-optimal dates; actual mission launch windows are determined by C3 (launch energy) budgets and may shift by several weeks. Real missions to Mars — including Curiosity (2011), InSight (2018), and Perseverance (2020) — all launched during windows computed with this method.