How a planet year works
Our idea of age comes from the Earth’s orbit. One lap around the Sun takes about 365.25 days, and each lap is a year. Other planets orbit at different distances and speeds. The closer a planet is to the Sun, the faster it moves and the shorter its year, which is why Mercury’s year is only 88 days and Neptune’s is 165 Earth years.
The calculator counts the days between your birth date and the date you choose, converts that to Earth years, and divides by each planet’s orbital period. It also shows how many Earth days you have to wait for your next birthday on the featured planet.
A worked example
Someone who has been alive for exactly 100 Earth years (36,525 days) would be about 53.2 years old on Mars (100 ÷ 1.8808), about 8.4 on Jupiter (100 ÷ 11.8626) and about 415 on Mercury (100 ÷ 0.2408). On Saturn, 100 Earth years is only 3.4 Saturn years.
What this does not tell you
Age on another planet is a fun reframing, not a medical or biological measure. Your body ages by time, and one day is still the Earth day you experience. Days on other planets differ too: a day on Venus lasts longer than its year.
For the exact years, months and days between two dates, use the age calculator or the date difference calculator.
Questions people ask
How do you work out your age on another planet?
A year on a planet is the time it takes to go around the Sun once. Divide the number of Earth years you have lived by that planet’s orbital period in Earth years. For Mars, which takes 1.88 Earth years, a 30-year-old is about 16 Mars years old.
What are the orbital periods used here?
We use sidereal orbital periods in Earth years from NASA’s planetary fact sheets: Mercury 0.2408, Venus 0.6152, Mars 1.8808, Jupiter 11.8626, Saturn 29.4475, Uranus 84.0168, Neptune 164.7913 and Pluto 247.9207. One Earth year is taken as 365.25 days.
Why is my age on Mercury so large?
Mercury is closest to the Sun and orbits in only 88 Earth days, so it has more than four birthdays for every Earth year. A person who is 30 on Earth is about 125 on Mercury.
Will I ever have a birthday on Neptune?
Only if you live to nearly 165. Neptune takes about 164.8 Earth years to orbit the Sun, so even someone who reaches 100 is only around 0.6 Neptune years old. It was discovered in 1846 and completed its first full orbit since then in 2011.
Is Pluto a planet?
Since 2006 the International Astronomical Union classifies Pluto as a dwarf planet. We include it because people still ask about it, and its 248-year orbit makes for a fun comparison.