Perpetual Calendar
This perpetual calendar tells you the day of the week for any date from 1 January in the year 1 to 31 December 9999. Type a date and it shows the weekday, which of the 14 possible calendars that year uses, other years with exactly the same calendar, and the same day in the other calendar. Dates before 15 October 1582 are counted in the Julian calendar, as they were written at the time; switch to the British setting, where the change came in September 1752, or use the Gregorian or Julian calendar for every date. Print any year as a one-page calendar, or the classic key with all 14 calendars, and download the key for every year as a CSV. Every one of the 3,652,059 days was checked against an independent count.
100% private — everything runs in your browser. The weekdays, the key and the files are made on your device; nothing is uploaded.
Date
Printable
Day of the week
Everything runs in your browser: nothing you type is uploaded, and only your settings are remembered in this browser (not the date you look up). Weekdays come from Julian Day Numbers worked out with whole-number formulas for the Gregorian and Julian calendars, checked for every day from 1 January 1 to 31 December 9999 against an independent day count. By default dates before 15 October 1582 are Julian; the British setting switches on 14 September 1752. Years start on 1 January in every setting. PDF export uses jsPDF and svg2pdf.js (MIT licence).
How to use the perpetual calendar (day of the week calculator)
- Type the day, pick the month and type the year (1 to 9999). The day of the week appears at once; press Today to go back to today.
- Choose the calendar setting: Gregorian from 15 October 1582 (the default), the British switch of 1752, or the Gregorian or Julian calendar for every date.
- Read which of the 14 calendars the year uses and which other years share it.
- Pick a preview (your year, the 200-year key or one of the 14 calendars), the first day of the week and the paper, then download the PDF or the CSV of the key.
What you can use it for
- Finding the day of the week you were born
- Checking the weekday of a historical date, in the calendar used at the time
- Reusing an old printed calendar for a year with the same layout
- Planning dates years ahead, such as anniversaries and events
- Teaching how calendars, leap years and the 1582 reform work
Perpetual calendar key 1900–2099
| Decade | +0 | +1 | +2 | +3 | +4 | +5 | +6 | +7 | +8 | +9 |
|---|---|---|---|---|---|---|---|---|---|---|
| 1900s | 2 | 3 | 4 | 5 | 13 | 1 | 2 | 3 | 11 | 6 |
| 1910s | 7 | 1 | 9 | 4 | 5 | 6 | 14 | 2 | 3 | 4 |
| 1920s | 12 | 7 | 1 | 2 | 10 | 5 | 6 | 7 | 8 | 3 |
| 1930s | 4 | 5 | 13 | 1 | 2 | 3 | 11 | 6 | 7 | 1 |
| 1940s | 9 | 4 | 5 | 6 | 14 | 2 | 3 | 4 | 12 | 7 |
| 1950s | 1 | 2 | 10 | 5 | 6 | 7 | 8 | 3 | 4 | 5 |
| 1960s | 13 | 1 | 2 | 3 | 11 | 6 | 7 | 1 | 9 | 4 |
| 1970s | 5 | 6 | 14 | 2 | 3 | 4 | 12 | 7 | 1 | 2 |
| 1980s | 10 | 5 | 6 | 7 | 8 | 3 | 4 | 5 | 13 | 1 |
| 1990s | 2 | 3 | 11 | 6 | 7 | 1 | 9 | 4 | 5 | 6 |
| 2000s | 14 | 2 | 3 | 4 | 12 | 7 | 1 | 2 | 10 | 5 |
| 2010s | 6 | 7 | 8 | 3 | 4 | 5 | 13 | 1 | 2 | 3 |
| 2020s | 11 | 6 | 7 | 1 | 9 | 4 | 5 | 6 | 14 | 2 |
| 2030s | 3 | 4 | 12 | 7 | 1 | 2 | 10 | 5 | 6 | 7 |
| 2040s | 8 | 3 | 4 | 5 | 13 | 1 | 2 | 3 | 11 | 6 |
| 2050s | 7 | 1 | 9 | 4 | 5 | 6 | 14 | 2 | 3 | 4 |
| 2060s | 12 | 7 | 1 | 2 | 10 | 5 | 6 | 7 | 8 | 3 |
| 2070s | 4 | 5 | 13 | 1 | 2 | 3 | 11 | 6 | 7 | 1 |
| 2080s | 9 | 4 | 5 | 6 | 14 | 2 | 3 | 4 | 12 | 7 |
| 2090s | 1 | 2 | 10 | 5 | 6 | 7 | 8 | 3 | 4 | 5 |
Find the year: its decade in the first column and its last digit along the top. The number is the calendar to use, 1 to 14. 1 to 7 are common years starting on Sunday, Monday, Tuesday, Wednesday, Thursday, Friday or Saturday; 8 to 14 are leap years starting on the same days. The tool prints a key like this for any 200 years from 1 to 9999.
The 14 calendars
| Calendar | Year type | Years 1901–2100 | Next from 2026 | In 400 Gregorian years |
|---|---|---|---|---|
| 1 | Common year starting on sunday | 21 | 2034, 2045, 2051, 2062 | 43 |
| 2 | Common year starting on monday | 21 | 2029, 2035, 2046, 2057 | 43 |
| 3 | Common year starting on tuesday | 22 | 2030, 2041, 2047, 2058 | 44 |
| 4 | Common year starting on wednesday | 22 | 2031, 2042, 2053, 2059 | 43 |
| 5 | Common year starting on thursday | 22 | 2026, 2037, 2043, 2054 | 44 |
| 6 | Common year starting on friday | 22 | 2027, 2038, 2049, 2055 | 43 |
| 7 | Common year starting on saturday | 21 | 2033, 2039, 2050, 2061 | 43 |
| 8 | Leap year starting on sunday | 7 | 2040, 2068, 2096 | 15 |
| 9 | Leap year starting on monday | 7 | 2052, 2080 | 13 |
| 10 | Leap year starting on tuesday | 7 | 2036, 2064, 2092 | 14 |
| 11 | Leap year starting on wednesday | 7 | 2048, 2076 | 14 |
| 12 | Leap year starting on thursday | 7 | 2032, 2060, 2088 | 13 |
| 13 | Leap year starting on friday | 7 | 2044, 2072 | 15 |
| 14 | Leap year starting on saturday | 7 | 2028, 2056, 2084 | 13 |
The Gregorian calendar repeats every 400 years (146,097 days, exactly 20,871 weeks), so the last column is the same for every 400-year span. The Julian calendar repeats every 28 years.
Julian and Gregorian dates
| Gregorian dates | Julian date is behind by |
|---|---|
| 15 October 1582 – 28 February 1700 | 10 days |
| 1 March 1700 – 28 February 1800 | 11 days |
| 1 March 1800 – 28 February 1900 | 12 days |
| 1 March 1900 – 28 February 2100 | 13 days |
| 1 March 2100 – 28 February 2200 | 14 days |
The calendar setting decides which calendar a date is read in. Default: the Julian calendar up to Thursday 4 October 1582, the Gregorian calendar from Friday 15 October 1582. British: the Julian calendar up to Wednesday 2 September 1752, the Gregorian calendar from Thursday 14 September 1752. Countries changed at different times; for a date from another country, check when it changed.
More date tools
Days between two dates, with business days: Day Counter. Is a year a leap year, and why: Leap Year Calculator. Day-of-year codes and astronomical Julian Day: Julian Date Converter. ISO week numbers: Week Number. Print a year or any month: 2027 Calendar and Calendar Maker.
More free calendars and planners
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See all free tools →Frequently asked questions
What is a perpetual calendar?
A calendar you can use for any year. Every year starts on one of seven weekdays and is either a common year or a leap year, so there are only 14 possible calendars. A perpetual calendar is a key that tells you which of the 14 a year uses, plus the 14 calendars themselves. This one also works out the weekday of any single date for you.
What day of the week is Christmas 2027?
Saturday. 25 December 2027 falls on a Saturday, and 1 January 2027 is a Friday.
Which years have the same calendar as 2027?
2027 is a common year starting on Friday: calendar 6. The years before it with the same calendar are 2021, 2010 and 1999, and the next ones are 2038, 2049 and 2055.
Why are there 14 calendars?
A year can start on any of the seven days of the week, and it is either a common year of 365 days or a leap year of 366. Seven times two gives 14. Calendars 1 to 7 are common years starting on Sunday to Saturday; 8 to 14 are leap years starting on Sunday to Saturday.
What happened in October 1582?
The Gregorian calendar replaced the Julian calendar in Catholic countries: Thursday 4 October 1582 was followed by Friday 15 October 1582, so 1582 had only 355 days. The weekdays carried on without a break. In the default setting this tool counts earlier dates in the Julian calendar and refuses 5 to 14 October 1582, which never happened there.
Why does the British setting switch in 1752?
Britain and its colonies kept the Julian calendar until 1752: Wednesday 2 September 1752 was followed by Thursday 14 September 1752, a year of 355 days. In that setting 1700 is still a leap year, so 29 February 1700 exists; in the default setting it does not.
How far apart are the Julian and Gregorian calendars?
13 days from 1 March 1900 to 28 February 2100: 1 January 2027 in the Gregorian calendar is 19 December 2026 in the Julian calendar. The gap grows by a day in each century year that is not divisible by 400.
Does it work for dates before year 1 (BC)?
No. It covers 1 January 1 to 31 December 9999. Years are numbered from 1 January in every setting, so a date that was written with a year starting on 25 March, as in England before 1752, may need its year moved by one for January to March.
How was it checked?
The weekday of every day from 1 January 1 to 31 December 9999 (3,652,059 days in the Gregorian calendar and 3,652,134 in the Julian calendar) was compared with an independent day count, and every Gregorian date also with the date functions built into the browser. The calendar number of every year from 1 to 9999 was checked against its first weekday and leap year.
Is my information uploaded?
No. Everything is worked out in this browser, and the files you download are made on your device.