Science / Space
How Old Are You on Other Planets? Age Calculator
Enter your date of birth to see your age in Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune years, how long a year lasts on each planet, and the date of your next birthday there.
How Old Are You on Other Planets? Age Calculator: A planet's year is the time it takes to go once round the Sun: 88 Earth days for Mercury, 687 for Mars, and almost 165 Earth years for Neptune. Your age there is the number of days you have lived divided by that planet's year, and your next birthday comes when the count reaches the next whole year. Runs 100% locally in your browser with zero server file uploads.
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A year is one trip around the Sun, so a planet closer in has short years and one further out very long ones: Mercury goes round in 88 days, Neptune in almost 165 Earth years. Your age on another planet is the days you have been alive divided by the length of that planet's year.
Orbital periods
The sidereal periods used, in Earth days: Mercury 87.97, Venus 224.70, Earth 365.26, Mars 686.98, Jupiter 4,332.59, Saturn 10,759.22, Uranus 30,688.5, and Neptune 60,182.
Weight too
Gravity differs as much as the years; see what you would weigh on each planet with the planet weight calculator.
How to use it
- Enter your date of birth.
- Read your age on each planet.
- Find your next birthday on Mars, or wait a lifetime for one on Neptune.
Privacy & limitations
Your date of birth stays in your browser.
Related tools
Frequently asked questions
Why am I so old on Mercury?
Mercury is closest to the Sun and goes round in only 88 days, so a 10-year-old has had more than 41 Mercury birthdays.
Will anyone have a birthday on Neptune?
Not in a lifetime: one Neptune year is almost 165 Earth years, so it has been round only once since it was discovered in 1846.
Do planet days matter?
Not for this: age counts trips around the Sun, not spins on the planet's axis.
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