Distance Between Planets Calculator
How close two planets get and how far apart they can be, from their average distances to the Sun.
- Closest approach (million km)78.3
- Farthest separation (million km)377.5
- Light travel time at closest (minutes)4.4
Inputs used
- First planetEarth
- Second planetMars
About this calculator
Planets don't sit still, so "how far is Mars?" has no single answer — the distance swings enormously as both planets circle the Sun. Treating orbits as circles at each planet's average distance, the closest the two can come is the difference of those distances, and the farthest is their sum, when they sit on opposite sides of the Sun.
For Earth and Mars that gives a range of about 78 to 378 million km — a five-fold swing, which is why Mars missions launch only in the brief window every 26 months when the gap is near its minimum.
Real orbits are slightly elliptical, so extremes can beat these circular-orbit figures: Mars's eccentric orbit let it come within a record 55.8 million km of Earth in 2003. Distances use each planet's semi-major axis from NASA's planetary fact sheet.
Quick reference
Closest approach to Earth
Circular-orbit geometry (difference of average solar distances), in millions of km.
| Second planet | Closest approach (million km) |
|---|---|
| Mercury | 91.7 |
| Venus | 41.4 |
| Mars | 78.3 |
| Jupiter | 628.9 |
| Saturn | 1,282.4 |
| Uranus | 2,717.4 |
| Neptune | 4,365.4 |
| Pluto | 5,756.8 |
Frequently asked questions
How close does Mars get to Earth?
About 78 million km on average-orbit geometry, but Mars's stretched orbit allows closer passes: the 2003 approach was 55.8 million km, the nearest in almost 60,000 years. At the other extreme the two planets can be 378 million km apart.
Which planet is closest to Earth?
Venus comes closest (about 41 million km at nearest approach), but averaged over time Mercury is the closest planet to Earth — and to every other planet — because it hugs the Sun and is never far from anyone's neighbourhood.
Why do Mars missions launch every 26 months?
Because that's how often Earth catches up to Mars and the distance between them collapses toward its minimum. Launching outside that window would mean chasing Mars across hundreds of millions of extra kilometres.
Results are informational only — not financial, medical or legal advice.