What is this tool for

This app will let you calculate how old would you be living on other planets.

Different Years

Planets circle the Sun at different paces and follow different orbits, thus their years and days vary from ours. Earth needs 365 days to go round the Sun, Mercury only 90 days, but for Pluto, it takes 250... years. See the animation below, where everything is sped up, where Earth's year lasts just a couple of seconds.

From nearest to Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

This animation is just to show planets' revolution speed relative to each other. Their size, orbits, and Sun aren't at the right scale. If you want to see the solar system at a proper scale, see our resources page

Different Days

Similarly with days. A day is a full planet rotation on its axis. It takes 24 hours for the Earth to do so, but Venus needs 243 earth days to make just one spin. Have a look at the video below.

Film przedstawia względną szybkość obrotu oraz nachylenie osi planet.

We can see that the fastest is Jupiter, thus it will lead at the number of days counted from the day you were born. Venus, being the slowest, has 243 times lower the day count than Earth.


Let's assume that today is your 18th birthday. Since you were born the Earth circled the Sun exactly 18 times. But Earth also spins around its axis. Before it circles the sun it will spin 365 times (a bit more actually) and that's how many days we have in Earth's year.

By multiplying that value by the number of years you live, we'll get the number of days that passed since you were born. In our case, it will be exactly 6575 days. You can say that you live for 18 years or 6575 days.

But because other planets rotate around the Sun and spin around their axis faster or slower than Earth - years and days count differently there.

Let's take Mercury, the planet closest to the Sun. Since your birthdate, it managed to rotate around the Sun almost 75 times, but only 112 times around its axis. We can say that you live for 75 Mercurian years, but only for 112 Mercurian days.

PlanetAge in yearsAge in days
Earth18 years6575 days
Mercury75 years112 days

Have a look here for more about calculations.

Makes your head spin?

No worries, we got you covered. We'll do the math for you.



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