Earth days to Mars days
Input
1 Earth day → MarsOutput
≈ 0.9747 Mars daysDivide by Mars’s day length (1.0259567 Earth days): one Earth day is a little under one Mars day.
Convert days between planets—Earth to Mars, Mars to Earth, or any pair from Mercury to Neptune—using each world’s day length in Earth-day units. See how long a day is on Mars and other planets, then read the live result above.
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A planetary day converter turns a count of days on one planet into the equivalent number of days on another, using each world’s published rotation length in Earth-day units—including Earth↔Mars.
A planetary day is how long a world takes to spin once about its axis—the local “day” used for sunrise-to-sunrise or rotation timing. It is not a year (one orbit around the Sun).
This converter takes a day count, a From planet, and a To planet, then scales by the ratio of their day lengths. You can convert Earth days to Mars days, Mars days back to Earth days, or any pair among Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto (reference).
The result is “how many local days on the target world equal your source count.” Example: 1 Earth day ≈ 0.9747 Mars days with this tool’s Mars day length of 1.0259567 Earth days (~24 h 37 m). Swap From/To to go the other way.
Use Age on Other Planets or the Planetary Year Converter when you need orbital years—not rotation days.
Rotation days ≠ orbital years—use this tool to convert local days between planets; use year/age tools for orbits.
Type how many days you want to convert (decimals allowed). The result updates live as you type.
Select the world whose day you are counting—for example Earth when converting Earth days to Mars days.
Select the target world—Mars for a Mars-day (sol-style) result, Jupiter for a short-day world, and so on.
The result shows target local days and the factor (how many target days equal one source day).
Use the day-length table and all-planets grid for context, or copy/share the URL (from, to, and amount stay in the query string for your session).
Input
1 Earth day → MarsOutput
≈ 0.9747 Mars daysDivide by Mars’s day length (1.0259567 Earth days): one Earth day is a little under one Mars day.
Input
1 Mars day → EarthOutput
≈ 1.026 Earth days (~24 h 37 m)One Mars day in this converter equals 1.0259567 Earth days—slightly longer than Earth’s 24-hour day.
Input
10 Mars days → EarthOutput
≈ 10.2596 Earth daysThe small daily offset accumulates: ten Mars days are more than ten Earth days of clock time.
Input
1 Earth day → VenusOutput
≈ 0.0041 Venus daysVenus’s sidereal day is ~243.025 Earth days, so one Earth day is a tiny fraction of one Venus day.
Input
1 Earth day → MercuryOutput
≈ 0.0171 Mercury daysMercury’s converter value is sidereal (~58.646 Earth days). Its solar day (~176 Earth days) is longer and is not used for this ratio.
Input
1 Earth day → JupiterOutput
≈ 2.4181 Jupiter daysJupiter’s day is ~0.41354 Earth days (~9.9 h), so more than two Jovian days fit in one Earth day.
Each planet has a day length expressed in Earth days (Earth = 1.000 mean solar day). The converter multiplies your amount by (source day length ÷ target day length).
Earth day vs Mars day: Earth is 1.000 Earth day (24 h). Mars in this tool uses 1.0259567 Earth days per local day (~24 hours 37 minutes). So Mars days run slightly longer than Earth days in the converter, and one Earth day equals fewer than one Mars day (≈ 0.9747).
Sidereal vs solar: a sidereal day is one spin relative to the stars; a solar day is noon-to-noon relative to the Sun. Earth uses the mean solar day as the unit. Mercury and Venus list both sidereal and solar lengths in the scientific table—the converter uses the sidereal values for those worlds. Jupiter–Neptune use published sidereal/equatorial rotation. Mission literature often quotes a Martian mean solar day near 24 h 39 m (~1.0275 Earth days); this page’s live math uses the converter table value 1.0259567 so on-page examples match the tool.
Formula
Target days = Source days × (source day length ÷ target day length)
Day lengths are in Earth-day units (NASA NSSDCA planetary fact sheet references).Day lengths used by this converter (Earth days per local day). Only bodies supported by the tool are listed.
| Planet | Earth days per local day | About | Notes |
|---|---|---|---|
| Jupiter | 0.41354 | ~9.9 h | Shortest day among the eight planets |
| Saturn | 0.44497 | ~10.7 h | Sidereal / equatorial reference |
| Neptune | 0.67125 | ~16.1 h | Sidereal reference |
| Uranus | 0.71833 | ~17.2 h | Sidereal; extreme axial tilt |
| Earth | 1.00000 | 24 h | Mean solar day (unit) |
| Mars | 1.0259567 | ~24 h 37 m | Converter day length |
| Pluto | 6.3872 | ~6.4 d | Reference body in this tool |
| Mercury | 58.646 | ~58.6 d | Sidereal (solar day ~176 Earth days) |
| Venus | 243.025 | ~243 d | Sidereal, retrograde (solar day ~117 Earth days) |
Aligned with NASA NSSDCA planetary fact sheet references—EverydayTools is not an official NASA calculator.
Side-by-side facts for the most common conversion on this page.
| Quantity | Earth | Mars (this converter) |
|---|---|---|
| Day length | 1.000 Earth day (24 h) | 1.0259567 Earth days (~24 h 37 m) |
| 1 Earth day equals | 1 Earth day | ≈ 0.9747 Mars days |
| 1 Mars day equals | ≈ 1.026 Earth days | 1 Mars day |
| 10 Mars days equal | ≈ 10.2596 Earth days | 10 Mars days |
Swap From/To in the converter to move either direction; results match these ratios.
Rotation length is not orbital period—pick the right tool.
| Question | This converter | Planetary Year Converter |
|---|---|---|
| Measures | Rotation (local day) | Orbit around the Sun (year) |
| Mars example | 1 Mars day ≈ 1.026 Earth days | 1 Mars year ≈ 687 Earth days |
| Best for | Day counts between planets | Year-length ratios |
Use Age on Other Planets when starting from a birth date and orbital periods.
Concise answers for common searches — definitions, steps, and comparisons.
In this converter, one Mars day is 1.0259567 Earth days—about 24 hours 37 minutes. One Earth day equals about 0.9747 Mars days. Mission writing often cites a mean solar sol near 24 h 39 m; examples on this page match the live calculator ratio.
Set From to Earth, To to Mars, enter Earth days, and read the result. With this tool’s ratio, Mars days = Earth days ÷ 1.0259567 (so 1 Earth day ≈ 0.9747 Mars days).
A planetary day is one rotation of a planet about its axis, expressed here in Earth-day units. It is not an orbital year. This page converts day counts between planets using those rotation lengths.
This page converts planetary rotation (local days). Use nearby tools for orbital age, year length, size, distance, weight, or daylight.
| Related tool | Use this tool when | Use related tool when |
|---|---|---|
| Age on Other Planets | You need to convert day counts between planets using rotation lengths. | You want age on other planets from a birth date (orbital years). |
| Planetary Year Converter | You are converting local days or Mars-day counts between worlds. | You need planetary year lengths (orbits), not day lengths. |
| Sunrise & Sunset on Other Planets | You need how long a full rotation/day lasts in Earth time. | You need daylight duration estimates by latitude on other worlds. |
| Planet Size Comparison | Your question is about day length or converting days between planets. | You want to compare planet sizes (diameter, volume) versus Earth. |
| Planet Distance Converter | You are converting rotation days between planets. | You need heliocentric distances in AU, km, or miles. |
| Weight on Other Planets | You need planetary day conversion. | You want surface-gravity weight scaling on other worlds. |
| Time Calculator | You are converting planetary days (rotation). | You need to convert Earth hours, minutes, and seconds only. |
A day is one spin; a year is one orbit. Use the Planetary Year Converter or Age on Other Planets for orbits.
Venus’s sidereal day is about 243 Earth days and retrograde—check the day-length table first.
This tool uses Mercury’s sidereal rotation (~58.646 Earth days). Sunrise-to-sunrise on Mercury is ~176 Earth days.
Many sources quote a mean solar sol near 24 h 39 m (~1.0275 Earth days). This converter uses 1.0259567 Earth days so the live result and examples stay consistent.
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A planetary day is one rotation of a planet about its axis. On this page it is measured in Earth-day units so you can convert day counts between worlds. It is not the same as a planetary year (one orbit around the Sun).
In this converter, one Mars day is 1.0259567 Earth days—about 24 hours 37 minutes. One Earth day equals about 0.9747 Mars days. Mission articles often cite a mean solar sol near 24 hours 39 minutes; examples here match the live calculator.
A sol is the name for a Martian solar day—the noon-to-noon day used in mission planning. Popular references put a mean sol near 24 h 39 m. This converter’s Mars day length is 1.0259567 Earth days; use the table when matching the tool’s results.
Yes, slightly. With this tool’s ratio, one Mars day is about 1.026 Earth days (~24 h 37 m), so Mars days run longer than Earth’s 24-hour day.
About 0.9747 Mars days. Set From to Earth, To to Mars, and enter 1 to see the live result.
Choose From: Earth, To: Mars, enter the Earth-day count, and read Mars days. Mathematically: Mars days = Earth days × (1 ÷ 1.0259567).
Yes. Pick any From and To pair among the supported planets, enter a day count, and use Swap to reverse the direction. All pairs use the same day-length ratio method.
Among the eight planets, Venus has the longest sidereal day—about 243 Earth days—and it rotates retrograde. Mercury’s solar day is longer still (~176 Earth days), but this converter uses Mercury’s sidereal value (~58.646 Earth days).
Jupiter has the shortest day among the eight planets—about 9.9 hours (0.41354 Earth days). Saturn is next at roughly 10.7 hours.
A sidereal day is one spin relative to distant stars. A solar day is noon-to-noon relative to the Sun. Earth uses the mean solar day as the unit here. Mercury and Venus show both lengths in the scientific table; conversion uses their sidereal values.
No. This page converts rotation days. For age in orbital years from a birth date, use Age on Other Planets; for year-length ratios only, use the Planetary Year Converter.
Day lengths align with the NASA NSSDCA planetary fact sheet. EverydayTools is an independent educational tool that references those published values—it is not an official NASA calculator or endorsement.
No. Conversions run entirely in your browser; nothing you type is uploaded.
Planetary Day Converter runs in your browser—inputs are not uploaded to EverydayTools servers.
Day lengths align with NASA NSSDCA planetary fact sheet references as implemented in the converter table (Earth = 1 mean solar day; Mars = 1.0259567 Earth days; Mercury/Venus = sidereal). Educational EverydayTools tool—not an official NASA product.
Educational astronomy only—not for spacecraft clock sync or navigation.
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Reviewed by EverydayTools Editorial Team on 2026-09-07.
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Earth Days ↔ Planetary Days
Enter a day count, pick planets, and see the ratio update live—no page reload.
Result
1 Earth day = 0.9747 Mars days
1 Earth day = 0.9747 Mars days
≈ 23.39 Earth hours on Mars
Tap any planet to load 1 local day → Earth days in the converter above.
Sort by column to compare rotation speed. Relative speed is spin rate versus Earth (higher = faster).
| Difference from Earth | ||||
|---|---|---|---|---|
| VenusRetrograde | 5832.6 h | 243.025 | +242.025 Earth d (+24202.5%) | 0.0041× Earth |
| Mercury | 1407.5 h | 58.646 | +57.646 Earth d (+5764.6%) | 0.0171× Earth |
| Mars | 24.62 h | 1.026 | +0.026 Earth d (+2.6%) | 0.9747× Earth |
| Earth | 24 h | 1 | Same as Earth | 1.00× Earth |
| UranusRetrograde | 17.24 h | 0.7183 | -0.2817 Earth d (-28.2%) | 1.3921× Earth |
| Neptune | 16.11 h | 0.6713 | -0.3287 Earth d (-32.9%) | 1.4898× Earth |
| Saturn | 10.68 h | 0.445 | -0.555 Earth d (-55.5%) | 2.2473× Earth |
| Jupiter | 9.92 h | 0.4135 | -0.5865 Earth d (-58.6%) | 2.4181× Earth |
Authoritative rotation periods from the NASA NSSDCA planetary fact sheet. Mars uses mean solar day (sol); Earth = 1 mean solar day.
| Planet | Sidereal rotation (Earth d) | Solar day (Earth d) | Hours (converter) | Earth days (converter) | Source |
|---|---|---|---|---|---|
| ☿ Mercury | 58.646 | 175.94 | 1407.5 | 58.646 | NASA NSSDCA |
| ♀ Venus | 243.025 | 116.75 | 5832.6 | 243.025 | NASA NSSDCA |
| 🌍 Earth | 0.9973 | 1 | 24 | 1 | NASA NSSDCA |
| ♂ Mars | 1.026 | 1.0275 | 24.62 | 1.026 | NASA NSSDCA |
| ♃ Jupiter | 0.4135 | ≈ sidereal | 9.92 | 0.4135 | NASA NSSDCA |
| ♄ Saturn | 0.445 | ≈ sidereal | 10.68 | 0.445 | NASA NSSDCA |
| ♅ Uranus | 0.7183 | ≈ sidereal | 17.24 | 0.7183 | NASA NSSDCA |
| ♆ Neptune | 0.6713 | ≈ sidereal | 16.11 | 0.6713 | NASA NSSDCA |
Rotation periods follow NASA NSSDCA planetary fact sheet values. Earth = 1 mean solar day (24 h). Mars converter day length = 1.0259567 Earth days (~24 h 37 m). Mercury/Venus use sidereal rotation for conversion (solar days differ). Other worlds use published sidereal/equatorial rotation.
A planetary day is how long a world takes to complete one rotation about its axis—the spin that creates day and night. It is not the same as a year (one orbit around the Sun). This converter scales day counts between planets using each world's day length in Earth-day units.
Earth's mean solar day is the unit: 1.000 Earth day (24 hours). Mars in this converter uses 1.0259567 Earth days per local day (~24 hours 37 minutes). So:
Set From to Earth and To to Mars (or swap) in the converter above—the live result uses the same ratio.
With this tool's table, a Mars day is slightly longer than Earth's 24-hour day (~24 h 37 m). Mission writing often calls the Martian solar day a sol and cites roughly 24 hours 39 minutes. Both figures are near 1.026 Earth days; examples and results on this page follow the converter value so they stay consistent with the calculator.
A sidereal day measures rotation against fixed stars. A solar day measures noon-to-noon relative to the Sun. On Earth the solar day is 24 hours; the sidereal day is about 4 minutes shorter because Earth advances along its orbit while spinning.
Sun distant star ★
↓ ↓
────●──── Earth at noon ────●──── same surface spot
│ spin │ spin (faster)
↓ ↓
────●──── must rotate extra ────●──── one sidereal turn
to face Sun again (~23h 56m)
Solar day (24 h) > Sidereal day (~23 h 56 m) because Earth moves along its orbit.Reference: NASA planetary fact sheet
| Statistic | Value |
|---|---|
| Jupiter day length | ~9.9 hours (~0.414 Earth days) |
| Mars day (converter) | 1.0259567 Earth days (~24 h 37 m) |
| Venus sidereal day | ~243 Earth days (retrograde) |
| Mercury solar day | ~176 Earth days |
| Neptune day | ~16.1 hours |
| Earth sidereal day | ~23 h 56 m |
| Planet | Day length | Hours | Earth days |
|---|---|---|---|
| ☿ Mercury | 58.646 Earth days | 1407.5 h | 58.646 |
| ♀ Venus | 243.025 Earth days (retrograde) | 5832.6 h | 243.025 |
| 🌍 Earth | Reference: 1 mean solar day (24 h) | 24 h | 1 |
| ♂ Mars | 1.026 Earth days | 24.62 h | 1.026 |
| ♃ Jupiter | ~9.92 h (0.4135 Earth days) | 9.92 h | 0.4135 |
| ♄ Saturn | ~10.68 h (0.445 Earth days) | 10.68 h | 0.445 |
| ♅ Uranus | ~17.24 h (0.7183 Earth days) (retrograde) | 17.24 h | 0.7183 |
| ♆ Neptune | ~16.11 h (0.6713 Earth days) | 16.11 h | 0.6713 |
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