Planetary Year Converter
Convert years between planets using each world’s orbital period around the Sun. Choose two planets, enter an amount, and get the equivalent orbital years instantly.
Convert years between planets
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How long is a year on Mars, Jupiter, Saturn, and Neptune?
A planetary year is one full orbit around the Sun. Mars takes 687 Earth days, or about 1.88 Earth years. Jupiter, Saturn, and Neptune take much longer because they travel farther from the Sun.
- How long is a year on Mars?
- ≈ 687 Earth days ≈ 1.8809 Earth years
- How long is a year on Jupiter?
- ≈ 4,332.59 Earth days ≈ 11.862 Earth years
- How long is a year on Saturn?
- ≈ 10,759.22 Earth days ≈ 29.4571 Earth years
- How long is a year on Neptune?
- ≈ 60,182 Earth days ≈ 164.7693 Earth years
How Long Is a Year on Each Planet?
These are mean sidereal orbital periods — the time to return to the same place against the distant stars. Earth is 365.25 days in this dataset, so “Earth-year equivalent” is simply days ÷ 365.25. Pluto is a dwarf planet and is available in the converter, not in this eight-planet table.
| Planet | Orbital period | Earth days | Earth-year equivalent | Relative to Earth |
|---|---|---|---|---|
| Mercury | 1 Mercury year | 87.97 | 0.2408 | 0.24× |
| Venus | 1 Venus year | 224.7 | 0.6152 | 0.62× |
| Earth | 1 Earth year | 365.25 | 1 | 1× |
| Mars | 1 Mars year | 687 | 1.8809 | 1.88× |
| Jupiter | 1 Jupiter year | 4,332.59 | 11.862 | 11.86× |
| Saturn | 1 Saturn year | 10,759.22 | 29.4571 | 29.46× |
| Uranus | 1 Uranus year | 30,688.5 | 84.0205 | 84.02× |
| Neptune | 1 Neptune year | 60,182 | 164.7693 | 164.77× |
Source: NASA Planetary Fact Sheet–style mean sidereal periods. NASA Planetary Fact Sheet. Shared EverydayTools orbital-period table. Mean sidereal years in Earth days — not IAU-adopted constants and not a live ephemeris.
How to use the converter
- Choose the planet you are converting from.
- Choose the destination planet.
- Enter the number of planetary years. Decimals such as 0.5 or 1.25 are supported.
- Read the instant conversion, Earth-day equivalent, and the all-planet comparison.
Planet year formula
Target planetary years = source amount × source orbital period ÷ target orbital period.
Using Earth-day constants: target years = (source years × source period days) ÷ target period days. Example: 1 Mars year ≈ 687 Earth days. 687 ÷ 365.25 ≈ 1.88 Earth years.
The default load is 1 Earth year → Mars years, which is 0.5317 Mars years (365.25 Earth days). That is a conversion of year units, not a birthday age.
Worked examples
These figures come from the same calculation engine as the tool, so they cannot drift from the result card.
- 1 Mars year = 1.8809 Earth years
- 5 Mars years = 9.4045 Earth years
- 1 Earth year = 0.5317 Mars years
- 1 Jupiter year = 11.862 Earth years
- 30 Earth years = 2.5291 Jupiter years
People also search “convert Mars years to Earth years,” “how long does Mars take to orbit the Sun,” and “how many Earth years is one Jupiter year.” Those are the same ratio: divide one world’s period by the other’s.
Planetary year vs planetary day
A planetary year is one complete orbit around the Sun. A planetary day is one rotation on the planet’s axis. Jupiter’s year is almost 12 Earth years, but its day is only about 10 Earth hours. Use the Planetary Day Converter for rotation. Use this page for orbital years.
If you want your age in Mars years from a birth date, that is the Age on Other Planets Calculator. This converter does not ask for a birthday.
Common mistakes when converting planetary years
- Confusing a planetary year with a planetary day. Orbit and spin are different clocks.
- Assuming every planet uses a 365-day year. Only Earth does, and this page uses 365.25 days.
- Mixing orbital period with rotation period, especially on Venus and Mercury.
- Using today’s planet-to-planet distance as a year length. Distance changes; mean orbital period does not.
- Mixing catalogs that round Mars to 687 days versus 686.98 days. Small period changes move the fourth decimal.
Frequently Asked Questions
- What is a planetary year?
- A planetary year is one complete orbit around the Sun. It is not a planetary day, which is one rotation on the planet’s axis.
- How long is a year on Mars?
- About 687 Earth days, or roughly 1.88 Earth years, using the mean sidereal period on this page.
- How many Earth years is one Mars year?
- One Mars year is 687 ÷ 365.25 ≈ 1.8809 Earth years in this dataset.
- How long is a year on Jupiter?
- About 4,332.59 Earth days, or roughly 11.86 Earth years.
- How long is a year on Neptune?
- About 60,182 Earth days, or roughly 164.8 Earth years — the longest year of the eight planets.
- How do you convert years between planets?
- Multiply the source amount by the source orbital period in Earth days, then divide by the target period. The math runs in your browser.
- What is the difference between a planetary year and a planetary day?
- A year is one orbit around the Sun. A day is one spin on the axis. Jupiter’s year is long; its day is only about 10 Earth hours.
- Does the calculator use orbital periods?
- Yes. Every conversion uses mean sidereal orbital periods in Earth days from one shared EverydayTools table.
- Is the planetary year converter free?
- Yes. It is free to use in the browser. No signup is required.
- Does the calculator work in the browser?
- Yes. Amounts and results stay on your device. Nothing is uploaded for a normal conversion.
- Is this the same as age on other planets?
- No. Age on other planets uses a birth date. This page converts any number of orbital years between two worlds.
- How long is a year on each planet?
- Mercury ≈ 88 days, Venus ≈ 225 days, Earth 365.25 days, Mars 687 days, Jupiter ≈ 11.86 Earth years, Saturn ≈ 29.46, Uranus ≈ 84.02, Neptune ≈ 164.8.
Shared EverydayTools orbital-period table. Mean sidereal years in Earth days — not IAU-adopted constants and not a live ephemeris. Last editorial review: 2026-10-03.
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