Donaldson R F Age on Other Planets
A "year" is simply how long a planet takes to go around the Sun. Enter your birthday to see your age in each planet's own years.
How this is worked out
This counts the number of days you have been alive (from your birthday to today, in Earth days) and divides that by how long each planet takes to complete one orbit of the Sun (its "year", in Earth days). Mercury's year is only 88 Earth days, so you would already have had hundreds of Mercury birthdays; Neptune's year is about 165 Earth years, so almost nobody reaches their first Neptune birthday.
This is a fun way to compare orbital periods, not a claim about how anyone would actually experience time differently — a day still feels the same length wherever you are.
Frequently asked questions
Why is the Moon not included?
The Moon orbits the Earth, not the Sun, so it does not have a "year" of its own in the same sense; see the Planet Facts Table for its actual orbital period around Earth (about 27.3 days).
Does this account for leap years?
Yes — it counts the exact number of calendar days between your birthday and today, so leap years are included automatically.
Related tools: Planet Facts Table, Planet Weight Calculator, Age Calculator.
Source / Last verified: orbital periods from NASA/GSFC, "Planetary Fact Sheet – Metric" (nssdc.gsfc.nasa.gov/planetary/factsheet), marked "Last Updated: 18 March 2025, DRW"; copied and checked on 27 September 2026.