Calculate Earth years from Mars years or Mars years from Earth years, with Earth days, sols, the span between two Earth dates, and the Earth date any number of Mars years later.

Duration estimate: an Earth year is 365.25 days. Calendar projections round to a whole day; they do not predict an exact orbital anniversary.

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Mars Years To Earth Years Formula

The following formula is used to convert Mars years to Earth years and vice versa.

E = M × (D / 365.25)

Variables:

  • E is the number of Earth years
  • M is the number of Mars years; D is the selected Mars-year length in Earth days.

The default orbital reference uses D = 686.98 Earth days and an Earth year of 365.25 days, giving about 1.880848734 Earth years per Mars year. Multiply by that ratio to convert Mars years to Earth years; divide by it for the reverse. The rounded textbook option uses 1.88 exactly. The table and example below use that textbook option; a custom basis uses your explicit positive day length.

Mars Years to Earth Years Conversion Table (1 Mars Year = 1.88 Earth Years)
Mars Years Earth Years
⅛0.235
⅙0.313
¼0.470
⅓0.627
½0.940
⅔1.253
¾1.410
11.880
1¼2.350
1½2.820
1¾3.290
23.760
2½4.700
35.640
47.520
59.400
611.280
7½14.100
916.920
1018.800
Conversion uses: 1 Mars year = 1.88 Earth years.

What is a Mars Year?

A Mars year is the period it takes for Mars to complete one orbit around the Sun. Due to the greater distance from the Sun, a Mars year is longer than an Earth year. Specifically, one Mars year is approximately 687 Earth days, or about 1.88 Earth years. This difference in orbital period means that seasons on Mars last much longer than those on Earth.

How to Calculate Mars Years to Earth Years?

The following steps outline how to calculate Mars years to Earth years.

  1. First, determine the number of Mars years (M).
  2. Next, choose the year basis and multiply Mars years by D / 365.25 to get Earth years (E).
  3. For the reverse, divide Earth years by D / 365.25 to get Mars years.
  4. Finally, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Number of Mars years (M) = 3

Using the rounded textbook option: equivalent Earth years (E) = 3 × 1.88 = 5.64. The default orbital reference gives about 5.64255 Earth years before display rounding.