Age on Other Planets Calculator – How Old Would You Be on Mars, Jupiter & Pluto?

Age on Other Planets Calculator

Generally, people can be divided into two groups – those who love celebrating their birthdays and those who don't 😉 Let's say you're one of the latter, approaching the magic number 40. Sounds like a midlife crisis is incoming. If only there were a way to be young again…

But what if we told you there is? The solution is simple – judge your age by extraterrestrial standards! Doing it might be a good idea for those on the other side of the birthday barricade, too – there are places in our Solar System where you can celebrate twice as often!

This calculator is an interactive tool designed to help you figure out your age, no matter the planet you're on. Use it to see when you'll celebrate your next birthday once we colonize Mars, and play around with it to see the differences between the planets of our Solar System.

How to use this calculator

This calculator is a simple, intuitive tool, and using it should prove no difficulties. All you need to do to get your age on other planets estimated is:

1. Pick what you want your calculations to be based on. You have the following two options:
   • Your birthday 🎂; and
   • Your age 🕐.
2. Input your date of birth or your age (in Earth years), depending on the option you choose.

And that's it! Our calculator will do all the work for you. You will get your age on all the planets of our Solar System – plus the Moon and Pluto – together with the date of your next birthday on each of them.

💡 See that little fact box below the results table? It changes for each celestial body! Pick different planets in the form, and enjoy a collection of fun facts about our Solar System.

How to count days and years on other planets

You might be asking yourself: why does our age even differ on the other planets? To understand this, we have to go through some basics about the way the planets move.

Days

The day-night cycle (or, in the case of the farther-out planets, where it's hard to distinguish between the two – simply counting days) depends on a sphere's rotation. Each planet spins on its own axis. For example, it takes the Earth around 24 hours (23 hours, 56 minutes, and 4.1 seconds, to be more specific), while on Mercury, it's a staggering 1,407.5 hours!

The specific rotation speeds and the differences between planets stem from none other than angular momentum. In short, when our Solar System first formed, it was from giant clouds of interstellar dust and gas, which spun around the supposed center point. Upon formation, this cloud separated into smaller pieces, each carrying a part of the initial momentum, dictating the rotation speed of each of the planets. So, in general, the planets closer to the Sun now have much longer days than their more distant neighbors.

Years

A year is the time a planet needs to complete one full orbit around the Sun. The farther away from the Sun a planet is, the longer the path it has to travel and the slower it moves – so the outer planets have enormously long years. Mercury zips around the Sun in just 88 Earth days, while distant Neptune needs almost 165 Earth years for a single lap.

Your age in "planet years" is therefore simply:

age on planet = your age in Earth days ÷ length of the planet's year (in Earth days)

A subjective ranking of our Solar System's planets

Mercury

The record-holder for the shortest year: only 88 Earth days. If you are 30 Earth years old, you are over 124 Mercury years old – and you get a birthday roughly every three Earth months. Paradoxically, Mercury spins so slowly (one rotation every 1,407.5 hours) that its day is longer than its year.

Venus

The strangest clock in the Solar System. Venus rotates backwards, and does it so slowly that a single rotation (243 Earth days) takes longer than its whole year (225 Earth days). On Venus, the Sun rises in the west – if you could see it through the clouds.

Earth

Our baseline: one year = 365.26 days. Nothing new here – except that the extra 0.26 of a day is exactly why we need a leap year every four years.

Mars

The future second home of humanity. A Martian year lasts about 687 Earth days, so your Mars age is roughly half of your Earth age – an instant rejuvenation! A Martian day (called a sol) is 24 hours and 37 minutes, pleasantly close to ours.

Jupiter

The giant is also the fastest spinner: a Jupiter day lasts under 10 hours. Its year, however, takes almost 12 Earth years – you probably haven't had many Jovian birthdays yet.

Saturn

With a year of about 29.5 Earth years, most people celebrate their first Saturn birthday around the same time as their Earth-side thirtieth. A "sweet sixteen" on Saturn would take almost five Earth centuries.

Uranus

The sideways planet rolls around the Sun on its side once every 84 Earth years. Each pole gets 42 years of continuous daylight followed by 42 years of night. Turning 1 on Uranus is a genuine achievement.

Neptune

Neptune's year lasts 164.8 Earth years. Since its discovery in 1846, it has completed just one full orbit – its first "discovery birthday" was celebrated in 2011.

The Moon

Not a planet, but our loyal companion. The Moon circles the Earth once every 27.3 days, so if we count each orbit as a "lunar year", you are already hundreds of Moon years old. Happy belated birthdays!

Pluto

The demoted dwarf planet takes about 248 Earth years to orbit the Sun. Nobody in recorded history has ever lived a single Pluto year – and since its discovery in 1930, Pluto hasn't completed even half of one orbit.

Milestones on other planets

Here is when some classic Earth milestones happen if you count them in other planets' years:

So if turning 40 on Earth feels heavy, remember: on Mars you're barely 21, on Jupiter you're a toddler of 3, and on Neptune you haven't even had your first birthday yet. 🎂🪐

FAQ

How old am I on Mars?

Divide your age in Earth days by 687 (the length of the Martian year in Earth days). A 30-year-old Earthling is about 15.9 Mars years old.

On which planet would I be the oldest?

On Mercury – its year is the shortest in the Solar System (88 Earth days), so your Mercury age is about 4.15 times your Earth age.

Why is a day on Venus longer than its year?

Venus rotates extremely slowly (and backwards): one full rotation takes 243 Earth days, while a full orbit around the Sun takes only 225 Earth days. So a Venusian day really is longer than a Venusian year.

Does this calculator use exact astronomical values?

Yes – it uses the sidereal orbital periods and rotation periods of each body (for example, 87.969 Earth days for Mercury's year and 1,407.6 hours for its rotation). The results are precise enough for any birthday party in the Solar System.