Below is the Martian calendar as calculated from Saturday, August 13, 2050; the date that Science Station on Mars was declared "permanent".
CALCULATING MARTIAN TIME
DAYS: Mars rotates on its axis every 24 hours, 37 minutes (and change). Mars requires an additional 37 minutes to be added somehow to its day. Since Earth Declared a Terran second and minute to be universal constants, Martian society chose to alter the first hour of each day. Therefore, what is a sixty minute hour on Earth between 12:00am and 1:00am on Mars is a ninety-seven minute hour. All other Martian hours are sixty minutes.
MONTHS: There are twenty-four months in a Martian year. January through December make up the first dozen months. They are followed by the "Tu" months, which are months beginning with "Tu" and containing the first three letters of the corresponding month. Therefore, the second January in a Martian year is called "Tujan". The second February is called "Tufeb", and so on.
YEARS: Unlike Earth, Martian months all have twenty-eight days. The exception is February, which has twenty-seven days, and Tufeb, which has twenty-six days. A standard Martian year has 669 days. This constitutes one revolution of Mars around the Sun.
LEAP YEARS: Similar to Earth, leap years are required to correct drift. Every third Martian year is a leap year and two additional days are assigned to Tufeb. Every fifteenth leap year - a total of forty-five Martian years - the leap year add just one day to Tufeb. The first Martian leap year was MD 0003
Following is a breakdown of a standard Martian year and a standard Martian leap year.
CONVERTING MARTIAN TO EARTH TIME
While the constants are fairly cumbersome, the formulae are fairly straightforward. Here are the primary conversions:
One (1) Earth day = .9747 Martian day
One (1) Martian day = 1.0259 Earth days
One (1) Earth year = .5316 Martian year
One (1) Martian year = 1.881 Earth years
A Reminder: Minutes and seconds are decreed to be universal constants.
The following table gives the corresponding Earth date for each Martian new year, starting with Martian Date (MD) 1 Jan, 0001 and ending with the MD 28 Tudec, 181; the day the Martian calendar was discontinued.