Planetary age: your age in other planets’ years

Every other system on this site is a calendar — something people built, argued about and use to decide when a festival falls. This one is not. It is one division: the time since you were born, divided by how long a planet takes to go round the Sun. That is worth knowing before reading any number on this page.

If you do not know the time, noon changes only the hours. The place sets the time zone your birth instant is read in, which is what the figures below are computed from.

The calculation runs entirely in your browser: nothing is sent anywhere, nothing is stored, and no cookie is set.

Your age in other planets’ years

Computed as of 29 September 2026. Where this calendar cannot answer for a date, it says so and gives the reason rather than extrapolating.

Worked example for a birth on 1 January 2000 (London): Planetary orbits — Not a calendar: elapsed time divided by each planet’s sidereal orbital period, from the NASA fact sheets.
Mercury ☿ 111.039 Mercury years 111 complete orbits; the current one has 85 Earth days to run.
Venus ♀ 43.471 Venus years 43 complete orbits; the current one has 119 Earth days to run.
Earth ♁ 26.743 Earth years 26 complete orbits; the current one has 94 Earth days to run.
Mars ♂ 14.219 Mars years 14 complete orbits; the current one has 537 Earth days to run.
Jupiter ♃ 2.255 Jupiter years 2 complete orbits; the current one has 3,230 Earth days to run.
Saturn ♄ 0.908 Saturn years 0 complete orbits; the current one has 992 Earth days to run.
Uranus ♅ 0.318 Uranus years 0 complete orbits; the current one has 20,918 Earth days to run.
Neptune ♆ 0.162 Neptune years 0 complete orbits; the current one has 50,421 Earth days to run.
Pluto ♇ 0.108 Pluto years 0 complete orbits; the current one has 80,792 Earth days to run.

See the same birth date in all nine calendars — Gregorian to the second, the other East Asian counts, Hijri, Hebrew, Solar Hijri and the planets.

What is actually being measured

A year, in this sense, is one orbit. The figure used here is the sidereal orbital period — the time a planet takes to return to the same position against the background stars — which is the number the fact sheets publish and the closest thing to an unambiguous definition of a planet’s year.

Nothing else about a calendar carries over. Mars has no months, no weeks and no dates; there is no Martian new year, because nobody has ever needed one. So “your age on Mars” is a ratio dressed up in the language of birthdays, and the interesting part is the ratio: Mars takes almost twice as long to go round, so the number is a bit over half the Earth figure.

Sidereal orbital periods, from the NASA planetary fact sheets. The Earth-years column is derived from the days column rather than quoted separately, so the two cannot disagree.
Body Symbol Orbital period (Earth days) Orbital period (Earth years)
Mercury ☿ 87.969 days 0.2408 Earth years
Venus ♀ 224.701 days 0.6152 Earth years
Earth ♁ 365.256 days 1.0000 Earth years
Mars ♂ 686.980 days 1.8808 Earth years
Jupiter ♃ 4,332.589 days 11.8618 Earth years
Saturn ♄ 10,759.220 days 29.4567 Earth years
Uranus ♅ 30,685.400 days 84.0107 Earth years
Neptune ♆ 60,189.000 days 164.7858 Earth years
Pluto (dwarf planet) ♇ 90,560.000 days 247.9357 Earth years

Pluto is on the list because it is interesting and because people look for it, not as a claim about its status: the International Astronomical Union reclassified it as a dwarf planet in 2006, and the table says so.

A worked example

Someone born on 15 May 1990, as of 29 September 2026. Every figure is computed when this page is built, by the same module the calculator uses.

Orbits completed since 15 May 1990 for a birth at noon UTC, as of 29 September 2026. The last column is how much longer the current orbit has to run.
Body Age in its years Complete orbits Current orbit completes in
Mercury 151.031 Mercury years 151 86 Earth days
Venus 59.128 Venus years 59 197 Earth days
Earth 36.375 Earth years 36 229 Earth days
Mars 19.340 Mars years 19 454 Earth days
Jupiter 3.067 Jupiter years 3 4,045 Earth days
Saturn 1.235 Saturn years 1 8,233 Earth days
Uranus 0.433 Uranus years 0 17,400 Earth days
Neptune 0.221 Neptune years 0 46,903 Earth days
Pluto 0.147 Pluto years 0 77,274 Earth days

Neptune’s year is 164.79 Earth years and Pluto’s is 247.94, both longer than any verified human lifespan, so those two rows will read zero for everyone. Uranus, at 84.01, is the outermost one anybody reaches.

Earth’s own year is the one this page divides by, and it is less settled than the single figure above suggests: the tropical, sidereal and anomalistic years all differ, and so do the three periods the planet takes to turn once. That is the subject of the Earth age page, along with the distance all this motion has carried you.

Where these numbers come from

Sidereal orbital period — one full revolution around the Sun, measured against the fixed stars — taken from the NASA planetary fact sheets. An age is elapsed time since birth divided by that period. Source: NASA Goddard Space Flight Center, planetary fact sheets.

These are averages of orbits that are ellipses, not circles, and that perturb each other slightly; the periods are quoted to the precision the fact sheets give and no further. Nothing here is a calendar: no planet but Earth has months, a new year, or a date. A birthday on Mars is a figure of speech for a point in an orbit.

One consequence worth stating plainly, because it makes the Earth row disagree with the Gregorian age on every other page of this site. The sidereal year is 365.256 days; the Gregorian calendar’s average year is 365.2425 days, because it tracks the seasons rather than the stars. The two differ by about twenty minutes a year. For the example above that is the difference between 36.375 sidereal years and 36 years 4 months 14 days on the calendar — the same instant, measured against two different definitions of a year.

Prose last reviewed 2026-08-20.

What this page is not

There is no astrology here. Orbital periods turn up in astrological writing — the roughly 29.5-year Saturn orbit is the basis of the “Saturn return” — and this site takes no position on any of that beyond noting that the orbital period is a measured quantity and the interpretation is not. The number in the table is the measurement.

Nor is it a countdown. The figures above say how much of an orbit has gone by, and that is all they say.