Common year starting on Friday

Last updated February 28, 2025

A common year starting on Friday is any non-leap year (i.e. a year with 365 days) that begins on Friday, 1 January, and ends on Friday, 31 December. Its dominical letter hence is C. The most recent year of such kind was 2021, and the next one will be 2027 in the Gregorian calendar,^[1] or, likewise, 2022 and 2033 in the obsolete Julian calendar; see below for more. This common year is one of the three possible common years in which a century year can end on, and occurs in century years that yield a remainder of 100 when divided by 400. The most recent such year was 1700, and the next one will be 2100.

From July of the year that precedes this type of year until September in this type of year is the longest period (14 months) that occurs without a Friday the 17th. Leap years starting on Tuesday share this characteristic, from August of the common year that precedes it to October in that type of year, (e.g. 2007-08 and 2035-36). This type of year also has the longest period (also 14 months) without a Tuesday the 13th, from July of this year until September of the next common year (that being on Saturday, e.g. 2021-22), unless the next year is a leap year (which is also a Saturday), then the period is reduced to only 11 months (e.g. 1999-2000 and 2027-28).

This is the one of two types of years overall where a rectangular February is possible, in places where Monday is considered to be the first day of the week. Common years starting on Thursday share this characteristic, but only in places where Sunday is considered to be the first day of the week.

Additionally, this type of year has three months (February, March and November) beginning exactly on the first day of the week, in areas which Monday is considered the first day of the week. Leap years starting on Monday share this characteristic on the months of January, April and July.

Calendars

Calendar for any common year starting on Friday,
presented as common in many English-speaking areas

ISO 8601-conformant calendar with week numbers for
any common year starting on Friday (dominical letter C)

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	January
53					01	02	03
01	04	05	06	07	08	09	10
02	11	12	13	14	15	16	17
03	18	19	20	21	22	23	24
04	25	26	27	28	29	30	31

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	February
05	01	02	03	04	05	06	07
06	08	09	10	11	12	13	14
07	15	16	17	18	19	20	21
08	22	23	24	25	26	27	28

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	March
09	01	02	03	04	05	06	07
10	08	09	10	11	12	13	14
11	15	16	17	18	19	20	21
12	22	23	24	25	26	27	28
13	29	30	31

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	April
13				01	02	03	04
14	05	06	07	08	09	10	11
15	12	13	14	15	16	17	18
16	19	20	21	22	23	24	25
17	26	27	28	29	30

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	May
17						01	02
18	03	04	05	06	07	08	09
19	10	11	12	13	14	15	16
20	17	18	19	20	21	22	23
21	24	25	26	27	28	29	30
22	31

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	June
22		01	02	03	04	05	06
23	07	08	09	10	11	12	13
24	14	15	16	17	18	19	20
25	21	22	23	24	25	26	27
26	28	29	30

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	July
26				01	02	03	04
27	05	06	07	08	09	10	11
28	12	13	14	15	16	17	18
29	19	20	21	22	23	24	25
30	26	27	28	29	30	31

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	August
30							01
31	02	03	04	05	06	07	08
32	09	10	11	12	13	14	15
33	16	17	18	19	20	21	22
34	23	24	25	26	27	28	29
35	30	31

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	September
35			01	02	03	04	05
36	06	07	08	09	10	11	12
37	13	14	15	16	17	18	19
38	20	21	22	23	24	25	26
39	27	28	29	30

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	October
39					01	02	03
40	04	05	06	07	08	09	10
41	11	12	13	14	15	16	17
42	18	19	20	21	22	23	24
43	25	26	27	28	29	30	31

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	November
44	01	02	03	04	05	06	07
45	08	09	10	11	12	13	14
46	15	16	17	18	19	20	21
47	22	23	24	25	26	27	28
48	29	30

Wk	Mo	Tu	We	Th	Fr	Sa	Su
	December
48			01	02	03	04	05
49	06	07	08	09	10	11	12
50	13	14	15	16	17	18	19
51	20	21	22	23	24	25	26
52	27	28	29	30	31

This is the only year type where the nth "Doomsday" (this year Sunday) is not in ISO week n; it is in ISO week n-1.

Applicable years

Gregorian calendar

In the (currently used) Gregorian calendar, alongside Sunday, Monday, Wednesday or Saturday, the fourteen types of year (seven common, seven leap) repeat in a 400-year cycle (20871 weeks). Forty-three common years per cycle or exactly 10.75% start on a Friday. The 28-year sub-cycle only spans across century years divisible by 400, e.g. 1600, 2000, and 2400.

For this kind of year, the ISO week 10 (which begins March 8) and all subsequent ISO weeks occur later than in all other years, and exactly one week later than Leap years starting on Thursday. Also, the ISO weeks in January and February occur later than all other common years, but leap years starting on Friday share this characteristic in January and February, until ISO week 8.

Gregorian common years starting on Friday^[1]
Decade	1st	2nd		3rd		4th	5th		6th	7th	8th		9th	10th
16th century	prior to first adoption (proleptic)												1582	1593	1599
17th century	1610	—		1621	1627	1638	1649		1655	1666	1677		1683	1694	1700
18th century	1706	1717		1723		1734	1745		1751	1762	1773	1779	1790	—
19th century	1802	1813	1819	1830		—	1841	1847	1858	1869	1875		1886	1897
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	2100
22nd century	2106	2117		2123		2134	2145		2151	2162	2173	2179	2190	—
23rd century	2202	2213	2219	2230		—	2241	2247	2258	2269	2275		2286	2297
24th century	2309	2315		2326		2337	2343		2354	2365	2371		2382	2393	2399

400-year cycle
0–99	10	21	27	38	49	55	66	77	83	94
100–199	100	106	117	123	134	145	151	162	173	179	190
200–299	202	213	219	230	241	247	258	269	275	286	297
300–399	309	315	326	337	343	354	365	371	382	393	399

Julian calendar

In the now-obsolete Julian calendar, the fourteen types of year (seven common, seven leap) repeat in a 28-year cycle (1461 weeks). 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 4, 15 and 26 of the cycle are common years beginning on Friday. 2017 is year 10 of the cycle. Approximately 10.71% of all years are common years beginning on Friday.

Julian common years starting on Friday
Decade	1st		2nd		3rd		4th		5th		6th		7th		8th		9th		10th
15th century	1406		1417		1423		1434		1445		1451		1462		1473	1479	1490		—
16th century	1501	1507	1518		1529		1535		1546		1557		1563		1574		1585		1591
17th century	1602		1613	1619	1630		—		1641	1647	1658		1669		1675		1686		1697
18th century	1703		1714		1725		1731		1742		1753	1759	1770		—		1781	1787	1798
19th century	1809		1815		1826		1837		1843		1854		1865		1871		1882		1893	1899
20th century	1910		—		1921	1927	1938		1949		1955		1966		1977		1983		1994
21st century	2005		2011		2022		2033	2039	2050		—		2061	2067	2078		2089		2095

Holidays

International

Valentine's Day falls on a Sunday
World Day for Grandparents and the Elderly falls on July 25
Halloween falls on a Sunday. This is the only year when Halloween falls in ISO week 43. They fall in ISO week 44 in all other years.
Christmas Day falls on a Saturday

Roman Catholic Solemnities

Epiphany falls on a Wednesday
Candlemas falls on a Tuesday
Saint Joseph's Day falls on a Friday
The Annunciation of Jesus falls on a Thursday
The Nativity of John the Baptist falls on a Thursday
The Solemnity of Saints Peter and Paul falls on a Tuesday
The Transfiguration of Jesus falls on a Friday
The Assumption of Mary falls on a Sunday
The Exaltation of the Holy Cross falls on a Tuesday
All Saints' Day falls on a Monday
All Souls' Day falls on a Tuesday
The Feast of Christ the King falls on November 21 (or on its latest possible date of October 31 in versions of the calendar between 1925 and 1962)
The First Sunday of Advent falls on November 28
The Immaculate Conception falls on a Wednesday
Gaudete Sunday falls on December 12
Rorate Sunday falls on December 19

Australia and New Zealand

Australia Day falls on a Tuesday
Waitangi Day falls on a Saturday
Daylight saving ends on April 4
ANZAC Day falls on a Sunday, and in some years coincides with Easter Sunday falling on its latest possible date
Mother's Day falls on May 9
Father's Day falls on September 5
Daylight saving begins on September 26 in New Zealand and October 3 in Australia

British Isles

Saint David's Day falls on a Monday
Mother's Day falls on March 7, March 14, March 21, March 28 or on its latest possible date of April 4
Daylight saving begins on March 28
Saint Patrick's Day falls on a Wednesday
Saint George's Day falls on a Friday, and in some years coincides with Good Friday falling on its latest possible date
Father's Day falls on June 20
Orangeman's Day falls on a Monday
Daylight saving ends on its latest possible date, October 31
Guy Fawkes Night falls on a Friday
Saint Andrew's Day falls on a Tuesday

Canada

Daylight saving begins on its latest possible date, March 14
Mother's Day falls on May 9
Victoria Day falls on its latest possible date, May 24
Father's Day falls on June 20
Canada Day falls on a Thursday
Labour Day falls on September 6
Thanksgiving Day falls on October 11
Daylight saving ends on its latest possible date, November 7

United States

Martin Luther King Jr. Day falls on January 18
President's Day falls on its earliest possible date, February 15
Daylight saving begins on its latest possible date, March 14
Mother's Day falls on May 9
Memorial Day falls on its latest possible date, May 31
Juneteenth falls on a Saturday
Father's Day falls on June 20
Independence Day falls on a Sunday
Labor Day falls on September 6
Grandparents' Day falls on September 12
Columbus Day falls on October 11
Daylight saving ends on its latest possible date, November 7
Thanksgiving Day falls on November 25

References

1 2 Robert van Gent (2017). "The Mathematics of the ISO 8601 Calendar". Utrecht University, Department of Mathematics. Retrieved 20 July 2017.

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[math-1] 1 2 Robert van Gent (2017). "The Mathematics of the ISO 8601 Calendar". Utrecht University, Department of Mathematics. Retrieved 20 July 2017.

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