---
title: "Age on Other Planets Calculator | Orbit Whisper"
description: "How old are you on Mars, Jupiter or Mercury? Enter your birth date for your age in each planet's years and the date of your next planetary birthday."
url: https://orbitwhisper.buzz/
---

Planetary birthdays

# Your age on other planets

Mercury races round the Sun in 88 days; Neptune takes nearly 165 years. Enter your birth date to see how many times each planet has circled the Sun in your lifetime, and when your next planetary birthday falls.

## How a planetary age is worked out

A year is one trip around the Sun, so your age on another planet is the number of days you have lived divided by the length of that planet's orbit in Earth days. Someone who has lived 9,799 days is 9,799 ÷ 686.98 = 14.26 Mars years old, but more than a hundred in Mercury years.

The calculator uses each planet's **sidereal** orbital period, one full circuit measured against the distant stars, from NASA's planetary fact sheets. A planetary birthday is the day that circuit completes, counted from midnight at the start of your birth date. Your Earth age follows the ordinary calendar, so it changes on your real birthday; a 29 February birthday falls on 28 February in other years.

The **Its days lived** column counts that planet's solar days, sunrise to sunrise: Mars sols last 24.66 hours, while one Venus day lasts 116.75 Earth days. Pluto is included as the best-known dwarf planet. Copy the table, or download it as a spreadsheet-friendly CSV.

## Sources

- Sidereal orbit periods and day lengths: [NASA Planetary Fact Sheets](https://nssdc.gsfc.nasa.gov/planetary/factsheet/) (David R. Williams, NASA Goddard Space Flight Center), the individual sheet for each planet.
- Definitions of the orbital and day-length figures: [NASA Planetary Fact Sheet notes](https://nssdc.gsfc.nasa.gov/planetary/factsheet/planetfact_notes.html).

## More space calculators

- [Weight on other planets](https://orbitwhisper.buzz/weight-on-other-planets/): What a bathroom scale would show on the Moon, Mars or Jupiter, and how high you could jump. Weigh in
- [Light travel time](https://orbitwhisper.buzz/light-travel-time/): How long light and radio take to reach the Moon, the Sun, every planet and the nearest stars. Send a signal
- [Solar System scale model](https://orbitwhisper.buzz/scale-solar-system/): Make the Sun a beach ball and find out how small the planets are and how far apart to place them. Build a model
- [Orbital period calculator](https://orbitwhisper.buzz/orbital-period-calculator/): Kepler's third law: the period from an orbit's size and mass, the size from a period, or weigh a planet. Do the orbit
- [Where is the ISS?](https://orbitwhisper.buzz/iss-tracker/): The space station's position right now on a world map, with day and night and its next 90 minutes. Find the station

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## Questions and answers

**Why am I younger on Mars and older on Mercury?**

A Mars year lasts 686.98 Earth days, almost twice as long as ours, so fewer Mars years fit into your life. Mercury needs only 87.97 days per orbit, so you have had about four Mercury birthdays for every Earth one.

**Why don't the numbers match another calculator exactly?**

Calculators differ in small ways: some multiply by rounded ratios such as 1.88 for Mars, and NASA's summary table lists tropical years, measured from equinox to equinox. This one divides the exact days you have lived by the sidereal periods, so differences of a few hundredths are normal.

**Will I ever have a Neptune birthday?**

Only at about 164.8 Earth years, so nobody has yet. Neptune has completed just one orbit since it was discovered in 1846. Uranus takes 84 years, so a first Uranus birthday is within reach of a long life.

**Is my birth date sent anywhere?**

No. The ages are worked out by this page in your browser and nothing you type is stored or sent.