A common year starting on Thursday is any non-leap year (i.e. a year with 365 days) that begins on Thursday, 1 January, and ends on Thursday, 31 December. Its dominical letter hence is D. The most recent year of such kind was 2015 and the next one will be 2026 in the Gregorian calendar[1] or, likewise, 2021 and 2027 in the obsolete Julian calendar, see below for more.
This is the only common year with three occurrences of Friday the 13th: those three in this common year occur in February, March, and November. Leap years starting on Sunday share this characteristic, for the months January, April and July. From February until March in this type of year is also the shortest period (one month) that runs between two instances of Friday the 13th. Additionally, this is the one of only two types of years overall where a rectangular February is possible, in places where Sunday is considered to be the first day of the week. Common years starting on Friday share this characteristic, but only in places where Monday is considered to be the first day of the week.
In the (currently used) Gregorian calendar, alongside Tuesday, the fourteen types of year (seven common, seven leap) repeat in a 400-year cycle (20871 weeks). Forty-four common years per cycle or exactly 11% start on a Thursday. The 28-year sub-cycle only spans across century years divisible by 400, e.g. 1600, 2000, and 2400.
This type of year has 53 weeks in the week-day format of the ISO 8601 standard.
| 1st ! | 2nd | 3rd | 4th | 5th | 6th | 7th | 8th | 9th | 10th | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 16th century | prior to first adoption (proleptic) | 1598 | |||||||||||||||
| 17th century | 1699 | ||||||||||||||||
| 18th century | — | 1795 | |||||||||||||||
| 19th century | 1891 | ||||||||||||||||
| 20th century | — | 1998 | |||||||||||||||
| 21st century | 2099 | ||||||||||||||||
| 22nd century | — | 2195 | |||||||||||||||
| 2291 | |||||||||||||||||
| — | 2398 | ||||||||||||||||
| 25th century | 2499 | ||||||||||||||||
| 0–99 | 9 | 15 | 26 | 37 | 43 | 54 | 65 | 71 | 82 | 93 | 99 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 100–199 | 105 | 111 | 122 | 133 | 139 | 150 | 161 | 167 | 178 | 189 | 195 | |
| 200–299 | 201 | 207 | 218 | 229 | 235 | 246 | 257 | 263 | 274 | 285 | 291 | |
| 300–399 | 303 | 314 | 325 | 331 | 342 | 353 | 359 | 370 | 381 | 387 | 398 |
In the now-obsolete Julian calendar, the fourteen types of year (seven common, seven leap) repeat in a 28-year cycle (1461 weeks). A leap year has two adjoining dominical letters (one for January and February and the other for March to December, as 29 February has no letter). This sequence occurs exactly once within a cycle, and every common letter thrice.
As the Julian calendar repeats after 28 years that means it will also repeat after 700 years, i.e. 25 cycles. The year's position in the cycle is given by the formula ((year + 8) mod 28) + 1). Years 3, 14 and 20 of the cycle are common years beginning on Thursday. 2017 is year 10 of the cycle. Approximately 10.71% of all years are common years beginning on Thursday.
| 1st ! | 2nd | 3rd | 4th | 5th | 6th | 7th | 8th | 9th | 10th | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 15th century | — | 1495 | ||||||||||||||||||||
| 16th century | 1579 < | -- Wikipedia year articles refer to Gregorian years from 1582 --> | 1590 | — | ||||||||||||||||||
| 17th century | 1601 | 1607 | 1618 | 1629 | 1635 | 1646 | 1657 | 1683 | 1674 | 1685 | 1691 | |||||||||||
| 18th century | 1702 | 1713 | 1719 | 1730 | — | 1741 | 1747 | 1758 | 1769 | 1775 | 1786 | 1797 | ||||||||||
| 19th century | 1803 | 1814 | 1825 | 1831 | 1842 | 1853 | 1859 | 1870 | — | 1881 | 1887 | 1898 | ||||||||||
| 20th century | 1909 | 1915 | 1926 | 1937 | 1943 | 1954 | 1965 | 1971 | 1982 | 1993 | 1999 | |||||||||||
| 21st century | 2010 | — | 2021 | 2027 | 2038 | 2049 | 2055 | 2066 | 2077 | 2083 | 2094 | |||||||||||