A year is not the same everywhere
A year is the time a planet takes to go once around the Sun. Earth needs 365.25 days, but Mercury, close to the Sun, needs only 88 days, while Neptune takes almost 165 Earth years. So your age depends on which planet’s calendar you use: younger than a toddler on Jupiter, a centenarian on Mercury.
How it is calculated
- Count the days between your birth date and the chosen date.
- Divide by the length of each planet’s year in Earth days.
| Planet | Year length (Earth days) | In Earth years |
|---|---|---|
| Mercury | 87.97 | 0.24 |
| Venus | 224.70 | 0.62 |
| Earth | 365.25 | 1 |
| Mars | 686.98 | 1.88 |
| Jupiter | 4,332.59 | 11.86 |
| Saturn | 10,759.22 | 29.46 |
| Uranus | 30,688.5 | 84.0 |
| Neptune | 60,182 | 164.8 |
The calculator also finds the date of your next birthday on Mars, when a whole new Martian year since your birth is complete.
Worked example
Someone born on June 15, 1995 has lived 11,464 days by November 3, 2026.
| Planet | Age |
|---|---|
| Earth | 31.39 years |
| Mercury | 130.32 |
| Venus | 51.02 |
| Mars | 16.69 |
| Jupiter | 2.65 |
| Saturn | 1.07 |
| Uranus | 0.37 |
| Neptune | 0.19 |
Their 17th Martian birthday falls on June 6, 2027. On Saturn they just turned one; on Neptune they will never reach their first birthday.
Fun facts
- Neptune was discovered in 1846 and completed its first full orbit since then only in 2011.
- A day on Venus, one turn on its axis, lasts 243 Earth days, longer than its year of 225 days.
- Jupiter’s year is close to 12 Earth years, which is why the planet moves through roughly one zodiac constellation per year in the night sky.
- Martian missions keep time in sols, Martian days of 24 hours 39 minutes, and a Martian year has about 668.6 sols.
Year versus day
This calculator uses each planet’s orbital period (its year). The length of a planet’s day is a different measure, the time it takes to spin once on its axis: about 10 hours on Jupiter and 24 hours 37 minutes on Mars.