Martian Calendars
| Calendar | Year Published | Days per Week | Days per Month | Months per Year | Base Year Length | Leap Days | Leap Day Position | Basic Intercalation Formula | Extended Intercalation Formula (\ denotes integer division) |
Mean Length of Calendar Year | Base Astronomical Year | Accuracy | Cycle of Perpetuity | Mean LS of Beginning of Year | Year Count Start | Epoch (CE) | Epoch (JD) | Notes |
| Aitken 1 | 1936 | 7 | 41-42 | 16 | 667 | 2 | undefined | 1x667 + 4x669 | -2 * (Y\5) | 668.6 | Vernal Equinox | 106 years | 2 years | 0.0 | undefined | undefined | undefined | |
| Aitken 2 | 1936 | 7 | 41-42 | 16 | 668 | 3 | undefined | 4x668 + 1x671 | 3 * (Y\5) | 668.6 | Vernal Equinox | 106 years | 2 years | 0.0 | undefined | undefined | undefined | |
| Aitken 3 | 1936 | 7 | 41-42 | 16 | 668 | 1-2 | mid-year + end of year | 5x668 + 4x669 + 1x670 | Y\2 + Y\10 | 668.6 | Vernal Equinox | 106 years | 2 years | 0.0 | undefined | undefined | undefined | |
| Allison | 1998 | 7 | 28-31 | 22 | 668 | 3 | end of 2nd month | 4x668 + 1x671 | 3 * (Y\5) | 668.6 | Winter Solstice | 238 years | none | 277.2 | 0 | 1873 Dec 29 12:02:23 | 2405521.502 | |
| Arih | 1999 | 7 | 37 | 18 | 668 | 1 | undefined | 2x668 + 3x669 | undefined | undefined | undefined | undefined | none | 273.4 | 1 | 2000 Jan 1 | 2451545 | |
| Bauregger | 1997 | 7 | 47-66 | 12 | 668 | 1 | end of 2nd month (of 12) | 4x668 + 6x669 | Y\5 + (Y-2)\5 + (Y-4)\5 | 668.6 | Winter Solstice | 238 years | none | 281.0 | undefined | undefined | undefined | |
| Becker | 1994 | 7 | 35 | 19 | 668 | 1 | mid-year | 4x668 + 6x669 | (Y-1)\2 + Y\10 + (Y-66)\100 + (Y-32)\200 | 668.615 | Winter Solstice | 52 years | 35 days | 270.0 | 1 | 0 Aug 2 | 1721272 | |
| Blort | 2001 | 7 | 55-56 | 12 | 667 | 1 | end of 2nd month (of 12) | 4x667 + 6x668 | undefined | 667.6 | Vernal Equinox | <1 year | none | 351 | 1 | 1 Jan 1 | 1721424 | |
| Briggs-Houben | 1997 | 7 | 42-70 | 12 | 665 | 7 | end of 8th month (of 12) | 49x665 + 51x672 | Y\2 + (Y-1)\100 | 668.5700 | Winter Solstice | 38 years | 1 year | 264-268 | 1 | 1975 Jul 7 | 2442601 | |
| Burroughs | 1913 | undefined | undefined | 12 | 687 | undefined | undefined | undefined | undefined | undefined | undefined | <1 year | undefined | undefined | undefined | undefined | undefined | |
| Clarke | 1951 | 7 | 50-60 | 12 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | |
| Coletti | 2004 | 7 | 55-56 | 12 | 668 | 1-3 | end of 2nd, 6th, and 9th months | 10x668 + 11x669 + 670 | Y\5 + (Y-2)\5 + (Y)\11 + Y\850 | 668.5918 | Mean Tropical | ~3000 years | none | 277.2 | 1 | 1873 Dec 29 00:00:00 UTC | 2405522.0 | |
| Compton | 1966 | undefined | 52-58 | 12 | 687 | undefined | undefined | undefined | undefined | undefined | undefined | <1 year | undefined | undefined | undefined | undefined | undefined | |
| Chromium | 2002 | 7 | 28 | 24 | 668 | 1 | end of year | 4x668 + 6x669 | (Y-1)\2 + Y\10 - Y\100 | 668.59 | Summer Solstice | 500 years | 28 days | 90.0 | undefined | undefined | undefined | |
| Cronin | 2001 | 7 | 29-31 | 23 | 668 | 1 | end of year | 4x668 + 6x669 | undefined | 668.6 | Winter Solstice | 238 years | none | 274.0 | 1 | 0 Jul 28 | 1721265 | |
|
Darian Darian Defrost Darian Hensel Areosynchronous Utopian Kepler |
1986 | 6-7 | 27-28 | 24 | 668 | 1 | end of year | 4x668 + 6x669 | Year 0-2000: (Y-1)\2 + Y\10 - Y\100 + Y\1000 Year 2001-4800: (Y-1)\2 + Y\10 - Y\150 Year 4801-6800: (Y-1)\2 + Y\10 - Y\200 Year 6801-8400: (Y-1)\2 + Y\10 - Y\300 Year 8401-10000: (Y-1)\2 + Y\10 - Y\600 |
668.5916129 | Vernal Equinox | ~10,000 years | 28 days | 0.0 | 0 | 1609 Mar 10 CE 18:00:40 UTC | 2308804.25046 | |
| Dechert | 1996 | 7 | 52-56 | 12 | 668 | 1 | end of 2nd month (of 12) | 4x668 + 6x669 | (Y-1)\2 + Y\10 - Y\100 + Y\500 | 668.5920 | Mean Tropical | 2300 years | none | 274.0 | 0 | 1999 Dec 31 20:42:25 | 2451544.36279 | |
| Douglass-Pickering | c. 1900 | 7 | 55-56 | 12 | 668 | 1 | end of year | 2x668 + 3x669 | Y\5 + (Y-2)\5 + (Y-3)\5 | 668.6 | Vernal Equinox | 145 years | none | 0.0 | undefined | undefined | undefined | |
| Elysium Mars | 1998 | undefined | 50-57 | 12 | 669 | undefined | undefined | 15/8 * 365/1.027491 | undefined | 666.06 | Mean Tropical | <1 year | undefined | 298.2 | undefined | 1975 Aug 30 | 2442669 | |
| Forget | 2001 | none | N/A | none | 668 | undefined | N/A | undefined | undefined | undefined | Vernal Equinox | undefined | none | 0.0 | undefined | undefined | undefined | |
| Forward | 1991 | 7 | N/A | none | 668 | 1 | vernal and autumnal equinoxes | 2x668 + 3x669 | undefined | undefined | Winter Solstice | undefined | 7 days | 270.0 | 0 | 1999 Dec 24 | 2451537 | |
| Gangale Stretched Gregorian | 1990 | 7 | 47-66 | 12 | 668 | 1 | end of 2nd month (of 12) | 4x668 + 6x669 | (Y-1)\2 + Y\10 - Y\100 + Y\200 | 668.5950 | Winter Solstice | 1250 years | none | 280.4 | 0 | 1975 Aug 14 | 2442639 | |
| Greg | 1880 | none | N/A | none | 668 | undefined | N/A | undefined | undefined | Vernal Equinox | undefined | undefined | none | 0.0 | undefined | -22981 | ||
| Hallet 1 | 1997 | 7 | 31-32 | 22 | 668 | 1 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | |
| Hallet 2 | 1997 | 7 | 55-56 | 12 | 668 | 1 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | |
| Hallet 3 | 1997 | 7 | 41-42 | 16 | 668 | 1 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | |
| Hartmann | 1997 | 7 | 55-56 | 12 | 670 | undefined | undefined | undefined | undefined | undefined | undefined | <1 year | 28 days | undefined | 1 | 1 CE | 1721424 | Year count increments on the terrestrial cycle. |
| Heinlein | 1949 | 7 | variable | 24 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | |
| Henry | 1967 | 7 | 45-70 | 12 | 668 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | |
| Heron | 2001 | 7 | 27-28 | 24 | 668 | 1 | end of 3rd month (of 24) | 4x668 + 6x669 | (Y-1)\2 + Y\10 - Y\100 + (Y-2)\500 - (Y-1)\5000 | 668.5918 | Winter Solstice | 250 years | none | 278.30 | 0 | 1975 Jul 26 | 2440429 | |
| Hollon | 1998 | 7 | 27-28 | 24 | 669 | 1 | end of year | 668, 669 by observation | N/A | 668.5906 | Vernal Equinox | infinite | 28 days | 0.0 | undefined | undefined | undefined | |
| Isakov | 2001 | undefined | 32-33 | 20 | 645 | undefined | undefined | undefined | undefined | 645 | undefined | < 1 year | undefined | undefined | undefined | undefined | undefined | |
| Innaky | 1997 | undefined | 29-30 | 23 | 687 | undefined | undefined | undefined | undefined | undefined | undefined | < 1 year | undefined | undefined | 0 | undefined | undefined | |
| Kretsch | 1999 | 7-8 | 31-32 | 21 | 668 | 1 | end of 1st month | undefined | undefined | undefined | Vernal Equinox | undefined | 32 days | 0.0 | undefined | undefined | undefined | |
| Krutein | 1999 | none | N/A | none | 668 | 1 | end of year | undefined | undefined | undefined | undefined | undefined | none | undefined | undefined | undefined | undefined | |
| Kuiper | 2001 | 7 | 55-56 | 12 | 667 | 1-2 | undefined | 37x667 + 668 | Y\38 + 2*(Y\590) | 667.0526 | Winter Solstice | < 1 year | undefined | 270.0 | undefined | undefined | undefined | |
| Levitt | 1954 | 6-7 | 55-56 | 12 | 668 | 1 | end of year | 2x668 + 3x669 | Y\5 + (Y-2)\5 + (Y-3)\5 - Y\1000 | 668.599 | Mean Tropical | 145 years | 56 days | 58.3 | 1 | 4713 Jan 1 | 0 | |
| Lovelock-Allaby | 1984 | 7 | N/A | none | 686 | 1 | end of year | 686 + 50x687 | -Y\51 | 686.98 | undefined | <1 year | 7 days | undefined | undefined | undefined | undefined | |
| Lowell | 1895 | 7 | 44-70 | 12 | 668 | 1 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | 278.3 | undefined | undefined | undefined | |
| Mars Pulse 1 | 1999 | 7 | 29-31 | 22 | 668 | 1 | end of year | undefined | undefined | undefined | Summer Solstice | undefined | 1 year | 90.0 | undefined | undefined | undefined | |
| Mars Pulse 2 | 1999 | 7 | 29-31 | 22 | 668 | 1 | mid-year | undefined | undefined | undefined | Winter Solstice | undefined | 1 year | 270.0 | undefined | undefined | undefined | |
| Mars Pulse 3 | 1999 | 7 | 29-31 | 22 | 668 | 1 | end of 5th month (of 22) | undefined | undefined | undefined | Winter Solstice | undefined | 1 year | 270.0 | undefined | undefined | undefined | |
| Martiana | 2002 | 7 | 27-28 | 24 | 668 | 1 | end of year | 4x668 + 6x669 | Year 0-2000: (Y-1)\2 + Y\10 - Y\100 + Y\1000 Year 2001-4800: (Y-1)\2 + Y\10 - Y\150 Year 4801-6800: (Y-1)\2 + Y\10 - Y\200 Year 6801-8400: (Y-1)\2 + Y\10 - Y\300 Year 8401-10000: (Y-1)\2 + Y\10 - Y\600 |
668.5916129 | Vernal Equinox | ~10,000 years | 28 days | 0.0 | 0 | 1609 Mar 11 CE 18:40:36 UTC | 2308805.27819 | |
| Millennium Mars | 1998 | 7 | 33-34 | 20 | 668 | 1 | end of year | undefined | undefined | undefined | Vernal Equinox | undefined | none | 0.0 | 0 | 1975 Dec 24 | 2442771 | |
| Moore | 1977 | undefined | 37-38 | 18 | 668 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | |
| Nagatomo | 1979 | undefined | 48-66 | 12 | 668 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | |
| Naughton-O'Meara | 2001 | 6-7 | 27-28 | 24 | 668 [see note] | 1 | end of year | 4x668 + 6x669 | undefined | 668.6 | Vernal Equinox | 106 years | 28 days | 0.0 | 0 | 1 Jan 1 | 1721424 | Year count increments on the terrestrial cycle. |
| Oosthoek | 2003 | none | 27-40 | 20 | 668 | 1 | end of 1st month | 668, 669 by observation | N/A | 668.5906 | Vernal Equinox | infinite | 1 year | 0.0 | 1 | 2022 Dec 26 | 2459940 | |
| Pavonian | 1999 | 8 | 33-34 | 20 | 668 | undefined | undefined | undefined | undefined | undefined | Vernal Equinox | undefined | 32 days | 0.0 | undefined | undefined | undefined | |
| Potassium Option 1 | 2002 | 7 | 35 | 19 | 668 | 1 | end of year | 4x668 + 6x669 | (Y-1)\2 + Y\10 - Y\100 | 668.59 | Winter Solstice | 172 years | 35 days | 270.0 | undefined | undefined | undefined | |
| Potassium Option 2 | 2002 | 7 | 35 | 19 | 668 | 1 | end of year | 4x668 + 6x669 | (Y-1)\2 + Y\10 - Y\100 | 668.59 | Autumnal Equinox | 250 years | 35 days | 180.0 | undefined | undefined | undefined | |
| Prud'homme | 2001 | 7 | 49 | 14 | 686 | undefined | undefined | undefined | undefined | undefined | undefined | <1 year | undefined | undefined | undefined | undefined | undefined | |
| Robinson 24-Month | 1993 | 7 | 27-28 | 24 | 669 | undefined | undefined | undefined | undefined | undefined | Winter Solstice | undefined | undefined | 272.1 | 1 | 2026 Apr 30 | 2461161 | |
| Robinson LS | 1993 | none | N/A | none | 669 | undefined | undefined | undefined | undefined | undefined | Vernal Equinox | undefined | none | 0.0 | 1 | 2026 Sep 29 | 2461313 | |
| Rohrer | 1977 | 7 | 35 | 19 | 667 | 1-3 | end of year | 5x667 + 4x668 + 669 | (Y)\2 + Y\10 + Y\50 | 667.62 | Autumnal Equinox | <1 year | 35 days | 180.0 | undefined | undefined | undefined | |
| Salvas | 2001 | 7 | 37 | 18 | 669 | 1 | end of 1st month (of 18) | 12x669 + 18x670 | Y - Y\3 - Y\10 | 669.601 | Winter Solstice | <1 year | none | 273.4 | 0 | 2000 Jan 1 | 2451545 | |
| Savard | 2002 | 7 | 29-30 | 22-23 | 652 | 29-30 | end of year | 21x652 + 27x681 + 682 | 29 * [Y + (Y-1) + (Y-3) + (Y-5)]\7 + 30 * (Y\49) | 668.5918 | Vernal Equinox | 833 years | none | 0 | undefined | undefined | undefined | |
| SCDTL | 1998 | 7 | 55-56 | 12 | 668 | 1 | end of year | 4x668 + 6x669 | (Y-1)\2 + Y\10 - Y\2000 | 668.5991 | 135 years | 0 | ||||||
| Schmidt | 1997 | 6-7 | 27-28 | 24 | 668 | 2-3 | undefined | 59x(4x668 + 1x670) + (4x668 + 1x671) | 2 * Y\5 + Y\300 - Y\6000 - Y\36000 | 668.4033 | Vernal Equinox | 5 years | 28 days | 0.0 | undefined | undefined | undefined | |
| Serra Martín 1 | 1997 | 7 | 53-56 | 12 | 669 | 3 | end of year | 4x669 + 1x672 | 3 * (Y\5) | 669.6 | Winter Solstice | <1 year | none | 270.0 | 0 | 1971 Oct 6 | 2441231 | |
| Serra Martín 2 | 1997 | 7 | 25-28 | 24 | 669 | 3 | end of year | 4x669 + 1x672 | 3 * (Y\5) | 669.6 | Winter Solstice | <1 year | none | 270.0 | 0 | 1971 Oct 6 | 2441231 | |
| Sherwood A | 1998 | undefined | 23-33 | 24 | 668 | 1 | mid-year | 2x668 + 3x669 | undefined | 668.6 | Vernal Equinox | 106 years | undefined | 0.0 | undefined | undefined | undefined | |
| Sherwood B | 1998 | undefined | 24-33 | 24 | 668 | 1 | end of 13th month (of 24) | 2x668 + 3x669 | undefined | 668.6 | Vernal Equinox | 106 years | undefined | 0.0 | undefined | undefined | undefined | |
| Sherwood C | 1998 | undefined | 27-28 | 24 | 668 | 1 | end of 19th month (of 24) | 2x668 + 3x669 | undefined | 668.6 | Vernal Equinox | 106 years | undefined | 0.0 | undefined | undefined | undefined | |
| Sherwood D | 1998 | undefined | 23-34 | 24 | 668 | 1 | end of year | 2x668 + 3x669 | undefined | 668.6 | Vernal Equinox | 106 years | undefined | 0.0 | undefined | undefined | undefined | |
| Space
Studies 200 University of North Dakota |
1999 | 7 | 60-62 | 11 | 669 | 3 | 1st, 2nd, and 3rd months | 4x669 + 1x672 | 3 * (Y\5) | 669.6 | undefined | <1 year | undefined | undefined | 0 | First human landing | undefined | |
| Ström 1 | 1997 | 7 | 55-57 | 12 | 668 | 1 | end of 2nd month (of 12) | undefined | undefined | undefined | undefined | undefined | undefined | 278.3 | 0 | 2012 Jan 1 | 2455928 | |
| Ström 2 | 1998 | 7 | 55-57 | 12 | 668 | 1 | end of 2nd month (of 12) | undefined | undefined | undefined | Vernal Equinox | undefined | undefined | 0.0 | 0 | 2012 Jan 1 | 2455928 | |
| Šurán Leap Day | 1997 | 7 | 21-28 | 24 | 668 | 1 | mid-year | 4x668 + 6x669 | Y\2 + (Y-1)\10 - Y\160 | 668.5937 | Winter Solstice | 476 years | 28 days | 270.0 | undefined | undefined | undefined | |
| Šurán Leap Week | 1997 | 7 | 21-28 | 24 | 665 | 7 | mid-year | 34x665 + 36x672 | 7 * [Y\2 + (Y-1)\70 - Y\1100] | 668.5936 | Winter Solstice | 454 years | 28 days | 270.0 | undefined | undefined | undefined | |
| Šurán Skip Day | 1997 | 7 | 21-28 | 24 | 668 | 1 | mid-year | 4x668 + 6x669 | -Y\2 + Y\10 - Y\160 | 668.5937 | Winter Solstice | 476 years | 28 days | 270.0 | undefined | undefined | undefined | |
| Šurán Skip Week | 1997 | 7 | 21-28 | 24 | 665 | 7 | mid-year | 34x665 + 36x672 | -7 * [Y\2 - (Y-1)\70 + (Y-1)\1100] | 668.5936 | Winter Solstice | 454 years | 28 days | 270.0 | undefined | undefined | undefined | |
| Thothian Wheel | 1998 | 7 | 30 | 22 | 668 | 1 | undefined | undefined | undefined | undefined | undefined | undefined | 30 days | undefined | undefined | undefined | undefined | |
| Titanium | 2002 | 6 | 30 | 22 | 668 | 1 | end of year | 4x668 + 6x669 | (Y-1)\2 + Y\10 - Y\100 | 668.59 | Vernal Equinox | 1300 years | 30 days | 0.0 | undefined | undefined | undefined | |
| Vanadium | 2002 | 7 | 29-31 | 23 | 668 | 1 | end of year | 4x668 + 6x669 | (Y-1)\2 + Y\10 - Y\100 | 668.59 | Vernal Equinox | 1300 years | none | 0.0 | undefined | undefined | undefined | |
| Vertregt | 1963 | 10 | N/A | none | 660 | 10 | undefined | 1x660 + 6x670 | Y/7 + Y/50 | 668.6 | Mean Tropical | 126 years | 1 year | undefined | undefined | undefined | undefined | |
| Vonnegut | 1959 | undefined | 30-31 | 22 | 669 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | |
| Vophick 1 | 1999 | 9 | 41-42 | 16 | 668 | 1 | end of 11th month (of 16) | 4x668 + 6x669 | undefined | 668.6 | Mean Tropical | 126 years | none | 280.2 | 1 | 1975 July 25 | 2440428 | |
| Vophick 2 | 1999 | 9 | 20-21 | 32 | 668 | 1 | end of 22th month (of 32) | 4x668 + 6x669 | undefined | 668.6 | Mean Tropical | 126 years | none | 280.2 | 1 | 1975 July 25 | 2440428 | |
| Vophick 3 | 1999 | 9 | 41-42 | 16 | 668 | 1 | end of 11th month (of 16) | 4x668 + 6x669 | (Y-1)\2 + Y\10 - Y\100 + Y\500 | 668.6 | Mean Tropical | ~1500 years | none | 273.4 | 1 | 1975 July 13 | 2440416 | |
| Weidner | 1999 | 7 | 29-32 | 22 | 668 | 1 | undefined | 2x668 + 3x669 | cyclic system | 668.5903 | Vernal Equinox | 3333 years | undefined | 0.0 | 0 | -4224 Aug 22 05:54:39 UTC | 178509.746282 | |
| Weiss | 2000 | 6 | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | undefined | |
| Woods | 1997 | 7 | 27-28 | 24 | 668 | 1 | undefined | 4x668 + 6x669 | Y\5 + (Y-2)\5 + (Y-4)\5 - Y\100 + Y\500 | 668.5920 | Autumnal Equinox | 500 years | none | 125.8 | 0 | 0 Nov 29 | 1721391 | |
| Zubrin | 1993 | undefined | 46-66 | 12 | 669 | undefined | undefined | 15/8 * 365/1.027491 | undefined | 666.06 | Vernal Equinox | <1 year | undefined | 0.0 | 1 | 1961 Jan 1 | 2437301 |
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Martian Time |
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Martian Time Survey 2.2 |