Your age depends entirely on what you are counting with. On Earth we measure age in trips around the Sun — one orbit takes 365.25 days. But Mars takes almost twice as long to complete an orbit: 687 Earth days. If you lived on Mars, you would celebrate a birthday only about once every two Earth years, which means a 30-year-old Earthling would be roughly 16 in Martian years.
Curious about your age on another world? Use our Astronaut Age Calculator to see your age in Martian years, lunar years, and more — instantly, based on your birth date.
How Long Is a Year on Each Planet?
Each planet orbits the Sun at a different speed and distance, so a “year” means something different everywhere:
| Planet | Orbital Period (Earth days) | Your Age at 30 Earth Years |
|---|---|---|
| Mercury | 88 | ~124 “years” old |
| Venus | 225 | ~49 |
| Earth | 365.25 | 30 |
| Mars | 687 | ~16 |
| Jupiter | 4,333 | ~2.5 |
| Saturn | 10,759 | ~1 |
Your age on Mars is simply your age in Earth days divided by 687. The Astronaut Age Calculator does this for any birth date, so you can find out how many Mars birthdays you have already had.
Does Space Travel Actually Change Your Age?
Yes — a little. According to Einstein’s theory of relativity, time passes slightly slower for objects moving at high speed or in weaker gravity. Astronauts on the International Space Station, orbiting at about 28,000 km/h, age a few milliseconds less than people on Earth over a six-month mission. It is nowhere near enough to matter for birthdays, but it is a real, measurable effect.
For a long Mars mission, the effect would still be measured in seconds or minutes over a multi-year trip — interesting for physics, irrelevant for cake candles.
Fun Ways to Use the Astronaut Age Calculator
- Find out how many Mars birthdays you have had — and when your next one is.
- Compare your age in Earth years, Martian years, and lunar years side by side.
- Figure out how old you will be on Mars when a planned mission lands (the 2030s).
- Settle the argument: are you “younger” on Jupiter? Technically yes — in Jupiter years.
Age is just a number — especially when the planet changes. Check your space age now with our free Astronaut Age Calculator.
