Age on Other Planets Calculator

Created by Juhi Raj, PhD candidate and Maria Kluziak
Reviewed by Dominik Czernia, PhD and Steven Wooding
Last updated: Nov 20, 2022

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.

💡 Don't forget to check our birthday calculator if you're interested to discover the brief history of celebrating birthdays.

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:

  • Pick what you want your calculations to be based on. You have the following two options:
    • Your birthday 🎂; and
    • Your age 🕐.

Input your date of birth, or your age, depending on the option you chose. If you pick your birthday, please make sure to follow this format: YYYY/MM/DD (year - month - day, for example, 1992/10/11).

And that’s it! Our calculator will do all the work for you. Below the first box, you will find the results – your age on all the planets of our solar system. And if you click on the advanced mode button at the bottom of the calculator, you’ll even see the exact day you’ll celebrate your birthday across our galactic neighborhood!
Note that you’re not limited to modifying the values in the first box. We encourage you to play around with any part of the calculator, and the rest will change accordingly!

💡 See that little fact box below the calculator? It changes for each planet! Feel free to play around with it, pick different celestial bodies, 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.


The day-night cycle (or, in the case of the further out planets, where it’s hard to distinguish between the too – simply counting days) depends on a sphere’s rotations. Each planet spins on its own axis. For example, it takes the Earth around 24h (23 hours, 56 minutes, and 4.1 seconds, to be more specific), while on Mercury, it’s a staggering 1407.5 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. This speed is dependent on where a planet formed in relation to the start of the angular momentum of the interstellar cloud that created them. So, in general, the planets closer to the Sun now have much longer days than their more distant neighbors.


Day length in hours


















On the other hand, years depend on a planet’s revolutions around the Sun. This is a much easier, more intuitive concept – a sphere simply takes this and that much time to complete a circle (or, to be more specific, an ellipse) around our life-giving star. The farther a planet is from the Sun, the more time it will likely need to go around its whole orbit. On top of the distance, the Sun's gravitational pull plays an important role here – planets close to the Sun, such as Mercury, need to go pretty darn fast to avoid being sucked up by the star; hence a Mercurian year is only 88 Earth-days long. Saturn, on the other hand, is being pulled much more weakly, so it moves significantly slower, and thus its years are over 10,000 days long.


Year length in Earth days

















A subjective ranking of our solar system's planets

Calculating your age on other planets is fun and all, but if you want to, say, celebrate your birthday on Mars – you would have to be there! Have you ever wondered what life on the other planets of our Solar system would look like? And – is it even possible for humans to live there in the first place? Let’s take a moment to get a closer look at our cosmic neighborhood and try to answer these questions! In this paragraph, you’ll find short overviews of the planets in our system, as well as our own totally subjective rating of how much we would like to colonize them 😉

Solar system


The average distance from the Sun: 36 million miles | 58 million kilometers
Type of surface: Terrestrial. It’s basically a rough, rocky ball.
Size: 2.6x smaller than Earth. Compared to Mercury, our planet looks like a giant!
Our will to colonize: 2/10.
You would think a small, rocky planet with a surface similar to our own Earth would be perfect. Too bad this planet’s hot to cold balance is absolutely crazy! Overall, the temperature on Mercury averages to a balmy 354 ºF / 180 ºC. That sounds sort of manageable – theoretically, we could build shelters that would be able to withstand that kind of heat, yes? Well, no – because you have to remember that is just the average! In reality, the temperature varies from freezing -330 ºF / -200 ºC during nighttime 🥶, to a scorching 800 ºF / 425 ºC on the sunny side 🥵! Talk about temperature fluctuations...


The average distance from the Sun: 67 million miles | 108 million kilometers
Type of surface: Terrestrial. Interestingly, on average, Venus’s surface is very young! It has tons of mountains and volcanoes, meaning that it’s still tectonically active.
Size: 1.1x smaller than Earth. That’s why some people call Venus our twin!
Our will to colonize: 1/10.
You thought Mercury was bad in terms of temperature? Prepare to hear about Venus… ok, ok. We have to admit; it’s more stable than its smaller neighbor. Is it really an improvement, though, when the temperature stabilizes at what is the solar system’s heat record? Venus can reach an astounding 900 ºF / 482 ºC! 🔥 That’s hot enough to melt lead, making it notoriously difficult for us to put infrastructure there. Combine that with a CO2-rich atmosphere and stinky, sulfuric clouds… no thanks. Even the admittedly fascinating, “backward” sunrises and sunsets (caused by the fact that Venus, for some mysterious reason, rotates in the opposite direction to the other planets) would not compensate for that!


The average distance from the Sun: 93 million miles | 150 million kilometers
Type of surface: Some water, some mountains, even some forests here and there… you know the drill!
Our will to colonize: 10/10.
We love our home!


The average distance from the Sun: 142 million miles | 228 million kilometers
Type of surface: Terrestrial. It’s small and rocky! Notably, despite its small size, Mars is home to Olympus Mons – the largest known mountain in the whole solar system.
Size: 1.9x smaller than Earth. Not quite as small as Mercury, but it’s no biggie either!
Our will to colonize: 8/10.
Who hasn’t watched or read at least one story about colonizing Mars? 👨‍🚀 This little red planet has been on our minds for decades, if not even longer! Although it’s not exactly welcoming – with its thin, CO2-rich atmosphere and planet-spanning deserts – it looks like it’s our best candidate for colonization for now. Relatively close, similar to Earth and, importantly, with its own water supply – after all, we can clearly see the ice caps covering its poles! The road ahead to making Mars habitable is long and winding, but we’ve already taken the first steps.


The average distance from the Sun: 484 million miles | 778 million kilometers
Type of surface: Gas. You could argue that Jupiter has no surface in the traditional sense at all!
Size: 11x larger than Earth. Jupiter is the biggest planet in the solar system! The “gas giant” name is definitely earned.
Our will to colonize: 3/10.
It might be hard to live on a giant ball of gas… Not to mention the gigantic storm ⛈️ haunting the planet. That storm cell has raged for over 100 years and is twice the size of Earth! We don’t know about you, but we wouldn’t like to find ourselves in the middle of that. However, while colonization per se is probably out of question, some people tentatively consider making use of Jupiter someday in the future. Ideas of “windbots” floating over the planet’s surface and harvesting the abundant gas for our benefit have been present in the minds of scientists for a few years. Sounds like science-fiction? Maybe, but hey – not too long ago, things we now consider everyday necessities like phones and cars were in that realm too. And if all else fails, there are 79 moons to choose from!


The average distance from the Sun: 886 million miles | 1.4 billion kilometers
Type of surface: Gas. Like Jupiter, Saturn is mostly made out of hydrogen and helium.
Size: 9.1x larger than Earth. Saturn is the second-largest planet in our neighborhood.
Our will to colonize: 4/10.
The situation here is pretty much the same as on Jupiter, minus the giant storm, which makes it a little bit more welcoming than its bigger neighbor. Then again, Saturn has one additional feature that makes the idea of living there sound pretty romantic. Can you imagine looking up to the sky and seeing these spectacular rings every day? Saturn has the most impressive ring system in our galactic neighborhood, with seven rings and several gaps and divisions between them. Another fascinating thing about this planet is that it’s practically its own little system, with a record number of as many as 82 moons! 🌙 Some of them have been confirmed to hold water, and could possibly support life.


The average distance from the Sun: 1.8 billion miles | 2.9 billion kilometers
Type of surface: Ice! Uranus’s surface is mostly composed of icy materials – water, ammonia, and methane - coving a small rocky core.
Size: 4x larger than Earth. It’s significantly smaller than its gas predecessors but still considerably larger than our home.
Our will to colonize: 4/10.
On the one hand – given its relatively solid surface, it would be much easier to try and build something here than on the gas giants we’ve covered before (duh!). On the other – brrrr! 🥶 All that ice must mean the temperatures on Uranus are less than welcoming. Indeed, on average, the planet gets as cold as -353 ºF / -214 ºC! Interestingly, Uranus is similar to Venus in the sense that it also rotates “backward”, that is, east to west. To add to that, it also rotates on its side!


The average distance from the Sun: 2.8 billion miles | 4.5 billion kilometers
Type of surface: Ice. The surface of Neptune is pretty much the same as Uranus.
Size: 3.9x larger than Earth. Neptune is very similar to Uranus in many aspects, including the size.
Our will to colonize: 4/10.
Here, the situation is pretty much the same as on Uranus – except that it’s even colder! On average, the temperature on Neptune can go as low as -373 ºF / -225 ºC. That’s way too cold for our liking! 🧊 It’s also important to remember that Neptune is the furthest planet from the Sun in our solar system, meaning that the days there are not exactly what we’re used to. Even the faint rings that can be seen from the planet’s surface are not convincing enough to try and live there!


The Moon

Distance from the Earth: ~238,855 miles | ~384,400 kilometers
Type of surface: Rocky.
Size: 3.7x smaller than Earth
Our will to colonize: 10/10
Chances are, we wouldn’t even be here today without our trusty satellite. It keeps the Earth from wobbling, moderates our climate, and takes care of the tides. Some theories even suggest it affects women’s menstrual cycles!
If we ever want to get serious about space exploration, colonizing our Moon is inevitable! While it’s not exactly the best place to live, it’s already being considered as a sort of a transit point between our own planet and the rest of the solar system. Imagine a giant, interstellar airport – not too far from Stanley’s Kubrick classic vision from 2001: A Space Odyssey. Who knows – we might see that vision come to life sometime in the not-too-far future 🚀


The average distance from the Sun: 3.7 billion miles | 5.9 billion kilometers
Type of surface: Rocky, but covered in ice.
Size: 5.5x smaller than Earth. Pluto’s surface area is roughly the same as Russia's.
Our will to colonize: 2/10.
We don’t care what they say, Pluto. You will always be a planet in our hearts 💕
Nevertheless, Pluto would probably not be a great place to live. There’s a good reason why it was reclassified as a dwarf planet in 2006. Tiny by space standards, it’s little more than an ice-covered rock floating at the outskirts of our solar system. On average, Pluto's temperature is -387 °F / -232 °C – way too low for our liking! Interestingly, it gains atmosphere periodically. When its orbit takes it a bit closer to the Sun, the ice caps thaw a little bit – enough to free some hydrogen, which creates a thin layer covering the surface.

Check out our lunar age calculator to find out your age in the Chinese and Hijri calculators. Or our birthday paradox calculator for fascinating trivia about the probability of people in a group having the same birthday.

Milestones on other planets

Now that you know what your age would be on the other planets, you’re probably curious about “real life” implications. So, when would you celebrate the important milestones if you were not on the Earth? Take a look at this short table and find out!

Average baby learning to walk

1st year of school in the US

Driver's license in the US

Legal age in the US

Minimum age of the US president

















































🔎 Now, are you wondering, "how about the effects of gravitational time dilation on my age?" Try to find that out be checking out our gravitational time dilation calculator.

Juhi Raj, PhD candidate and Maria Kluziak
Learn how your age would vary if you calculated it on different planets of the solar system!👶🏻🧓🏽
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Planets in our solar system
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Dwarf planet & the Moon
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Fun fact about planet Earth.
Earth is the fifth largest planet of our solar system and has one large natural satellite, the Moon.
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