Preceden

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Supported Date Formats

Preceden supports a wide variety of date and time formats.

Quick Tips for Formatting Dates & Time

A few things to know before you start typing dates:

  • Month names work in upper or lower case, spelled out or abbreviated.
  • Commas are optional, both within a date and as separators in large years.
  • Years can be shortened to two digits, either on their own (95) or in a full date (5/8/95, May 8, 95): 30 to 99 are read as the 1900s, 00 to 29 as the 2000s. A month with a two-digit year and no day, like Mar 95 or 5/95, is rejected, so write Mar 1995 or 5/1995 instead.
  • For the years 1 to 99 AD, include the AD after the year so it is not read as a shortened modern year.
  • Include a year with a month and day. A date like May 21 or 6/19 on its own is rejected as "not a supported date format". Older events saved that way are left off the timeline, and the event list below it says "This start date format is no longer supported." (or "This end date format is no longer supported." when the end date is the problem) until you add the year.
  • Spaces before BC/AD and before AM/PM are optional.
  • Slashes and dashes put the month first (5/8/2022 and 5-8-2022 are May 8), but periods and spaces put the day first (05.08.2022 and 05 08 2022 are 5 August). A dashed date whose first number is over 12 cannot be month first, so 18-08-2014 is read as 18 August. A date that starts with the year, like 2022-05-08, 2022/05/08 or 2022.05.08, is read as year, month, day.
  • A month and year joined by a dash, like 3-2018 or 07-1789, is read as that month. The exception is a two-digit month before a year from 2000 on: 07-2020 is read as the range 2007 to 2020, so write July 2020 or 7/2020 for the month. Written year first, as in 1988-09, it is read as the month too, unless the month is above the last two digits of the year: 1910-12 is read as 1910 to 1912.
  • Preceden supports dates ranging from 240,000 BC to 240,000 AD.
  • End dates are inclusive: when you specify an end date, Preceden assumes the event includes that date.
  • Dates have to be real calendar dates. For a fictional calendar with its own months or year names, use the stand-in years in Timelines Without Dates.

Date Formats

  • 2022
  • May 2022
  • 5/2022
  • May 8, 2022
  • May 8th, 2022
  • 5-8-2022
  • 2022-05-08, 2022/05/08 or 2022.05.08
  • 5/8/2022 - Note that this is MM/DD/YYYY, the order used in the US; if your country writes DD/MM/YYYY, use the next format instead. A date like 25/12/2022 is rejected as an invalid date, because Preceden reads the 25 as the month.
  • 8 May 2022 - Use this one if your country writes dates as DD/MM/YYYY.
  • 8.5.2022 or 08.05.22 - A date written with periods is read as day.month.year, unless the second number is over 12: 1.23.2003 is January 23. The month can also be a name, so 19.June.1623 is June 19, 1623, and 05.Mar.1945 and 28.Juli.1914 work too.
  • 8 5 2022 - Three numbers separated by spaces are also read as day month year, unless the second number is over 12: 6 30 2023 is June 30.
  • 8th of May 2022
  • 8 de Mayo 2022
  • 8 de Mayo de 2022 - An era can follow the year, so 15 de marzo de 44 a. C. is March 15, 44 BC, 12 de abril de 65 d. C. is April 12, 65 AD, and the Portuguese 19 de junho de 384 a.C works too.
  • Year 1656 - A label in front of the year is dropped, so Year 1656, Año 1803, Años 1980, Anno 1492 and año de 1247 all save as the year alone, and so does Year 27 BC. The year needs three or more digits or an era after it: Year 65 on its own is rejected, because it often counts the years of a life rather than naming a date. The Arabic عام and سنة and the Persian سال work the same way before a year from 1500 on, or before any year with an era (عام 63 ميلادي), because a lower year written after them is often on the Islamic or Iranian calendar. A preposition in front of a date is dropped too, so En 1973, En junio de 2013, À 2030 and In January 1972 save without it, and A mediados del siglo XIX is read the same as mediados del siglo XIX.
  • 60,000 BC - For years before year 1 we support BC, BCE, BP, FVT and AC (the Spanish antes de Cristo), and for years after it AD, CE, DC and EVT; periods and spaces between the letters are optional. AD, BC, BCE and CE can also go before the year, as in AD 105. BP is counted like BC, from year 1 rather than from 1950, so 1000 BP saves as 1000 BC. For dates within the last few thousand years, convert BP to BC or AD first (1000 BP is about 950 AD).
  • 10,000 years ago - A date counted back from today is saved as an approximate year, with Approx. checked. 12 thousand years ago and the Spanish hace 5000 años work too, as do the Italian 10.000 anni fa or 12mila anni fa, the French Il y a 10 000 ans, the Portuguese Há 5000 anos, the German vor 12000 Jahren and the Dutch 20.000 jaar geleden. Ten thousand years or more are counted back from year 0, so 10,000 years ago saves as 10000 BC. From 1,000 to 9,999 years are counted back from the year 2000, so 4000 years ago saves as 2000 BC. Fewer than 1,000 are counted back from the current year, so 200 years ago typed in 2026 saves as 1826. The year is fixed when you save, so unlike Present it does not move as time passes.
  • Set the start date to Today and the event starts at the beginning of the current UTC date. Set the end date to Today and it ends at the end of that day.
  • A start or end date of Now, Present, or Ongoing reflects the current date and time, unlike Today, which reflects only the date. Current and Present day work the same way. Preceden treats all of these as the same date, so pick the word you want to read on your timeline: with the default Unformatted event date format, an event whose end date is Present displays it as Present rather than as today's date.
  • Today, Now, Present and Ongoing are worked out again every time the timeline loads, which is the reason to use them instead of typing today's date. An event that ends Present keeps running up to the current day on its own, and its duration grows without anyone editing it.
  • These words work in other languages too. Hoy, heute and aujourd'hui behave like Today, and ahora, jetzt, maintenant and adesso behave like Now.
  • You can enter both dates in the start date field separated by a hyphen, and Preceden will split them for you: 2018 - 2022. An end year written with only its last two digits, like 1832-33 or 1914–18, stays in the start year's century. Two years joined by a slash, like 1945/1946 or 1870/80, are read as a range too, and so are two years joined by a word: 1914 to 1918, the Spanish 1140 a 1160 or 1990 al 1995, the French 1500 à 1600, and the Portuguese até, Dutch tot and German bis.
  • You can also enter a decade such as 1940s, which is split into 1940 to 1949 when the event is created. A three-digit decade is read as AD, so 840s runs from 840 to 849; add an era to say so outright (840s AD) or for a BC decade, which counts down: 140s BC runs from 149 BC to 140 BC. A three-digit round hundred is read as the whole century, so 700s runs from 700 to 799 and 500s BCE from 500 BCE to 401 BCE. Russian and Ukrainian decades work too: 1980-е, 1920-х, 1410-е годы and 2010-ті are read as the 1980s, 1920s, 1410s and 2010s, and one can carry an era: 1750-е годы до н.э. runs from 1759 BC to 1750 BC. So do French, Spanish and Portuguese decades written out with a four-digit year: Années 1980, Década de 1960 and Décadas de 1950 are read as the 1980s, 1960s and 1950s, as are the other ways Spanish writes a decade, such as En la década de 1960, Década 1970, Década del 2000 and Década de los años 1920. The word for decade can be left out, so Los 2000 is the 2000s, and Principios de los años 1950 and the Portuguese Final dos anos 1950 are the early and late 1950s. A Spanish decade can also name its century: Década de los 40 del Siglo XX is the 1940s, and a decade counted within a century works too, so Primera década del siglo XXI is the 2000s and Última década del siglo XIX the 1890s. So do Italian ones: Anni 2000 is the 2000s, anni 1970 the 1970s, and a decade can name its century in Roman numerals instead, so anni '70 del XX secolo is also the 1970s. Inizio, Metà and Fine in front work like early, mid and late, so Fine anni 1920 is the late 1920s and Metà degli anni 1980 the mid 1980s. So do Romanian ones: Anii 1920 is the 1920s, and Începutul anilor 1990 and Sfârșitul anilor 1980 are the early 1990s and late 1980s. Two of them joined by a word, such as Décadas de 1950 y 1960 or Années 1960 et 1970 typed in the start date field, run from the first year of the first decade to the last year of the second. Two joined by a dash work too: Décadas de 1960–1980 runs from 1960 to 1989, and the second can be shortened, so Décadas de 1960–70 runs from 1960 to 1979. A two-digit decade such as 40-е or Années 70 is not, since it does not say which century.
  • A century works the same way: 19th century becomes 1800 to 1899, and 5th century BC becomes 500 BC to 401 BC. When an era follows the number you can leave out the word century, so 5th BC and 13th CE are read as centuries as well. A Roman numeral works in place of the number, so XIX century is 1800 to 1899 and VIII century BC is 800 BC to 701 BC. A numeral from II to XXI typed on its own is read as that century too, so XIX is 1800 to 1899, though a single letter such as X is not. You can spell the number out as well, as long as the word century follows it: Nineteenth Century is 1800 to 1899 and second century BCE is 200 BC to 101 BC. Two Spanish centuries can share the word Siglos: Siglos XV–XVI runs from 1400 to 1599, Siglos V al XV and Siglos XVIII y XIX are read the same way, and an era at the end covers both, so Siglos VI–IV a. C. runs from 600 BC to 301 BC. Two Russian or Ukrainian centuries can share one word the same way: XVIII–XIX вв. runs from 1700 to 1899, X–XII века and XVII–XVIII ст. are read the same way, and IX - VIII вв. до н.э. runs from 900 BC to 701 BC. Two Italian centuries can share one word too: XVIII e XIX secolo runs from 1700 to 1899 and VII–VI sec. a.C. from 700 BC to 501 BC. One Italian century can be abbreviated, with or without the dot, so Sec. XV runs from 1400 to 1499 and Sec XIX from 1800 to 1899, and it can take an Italian or English era: VIII sec. a.C. runs from 800 BC to 701 BC, VII sec. BC from 700 BC to 601 BC and II secolo AD from 100 to 199. A Romanian century takes its era at the end, so Secolul I î.Hr. runs from 100 BC to 1 BC. Centuries written in other languages work too: the Spanish Siglo XIX, the Portuguese Século XIX, the French XIXe siècle, the Italian XIX secolo or 19° secolo, the Romanian Secolul XIX, the Russian XIX век, the Ukrainian XIX століття, the Greek 19ος αιώνας, the Kazakh 19 ғасыр and the Hindi 19वीं सदी or 19वीं शताब्दी all become 1800 to 1899. In the end date, a century counts as its last year, so a start date of 1750 and an end date of 19th century runs from 1750 to 1899.
  • Put early, mid or late in front of a century, decade, year or month to narrow it down, and the dates it fills in are marked approximate: late 19th century runs from about 1875 to 1899, early 1950s from about 1950 to 1953, late 1941 from about October to December 1941, and late March 1918 from about March 21 to 31, 1918. Early covers the first ten days of a month and mid the next ten. A hyphen works as well as a space, so mid-1950s and Mid-Apr 2025 read the same as mid 1950s and mid Apr 2025. You can also write the part out: End of the 19th century, Beginning of 1862, Middle of the 1950s and End of May 2025 are read as late, early, mid and late. Before a year, the word on its own works too, in English, French, German, Italian or Dutch: end 2017 and Fin 2015 are late 2017 and late 2015, début 2013, Anfang 1945 and inizio 1943 are early in those years, and Mitte 1943 is mid 1943. In front of a month, include the year after it. The Russian and Ukrainian words work in front of a year, decade or month too: конец 1646 is late 1646, начало 1950-х the early 1950s, кінець жовтня 1921 late October 1921, and середина, початок and кінець read the same way. So do the Spanish, Portuguese and French words in front of a written-out decade: Mediados de la década de 1970 is the mid 1970s, Final da década de 1980 the late 1980s and Début des années 1990 the early 1990s. The Italian Inizio, metà and Fine work in front of a century: Fine del XIX secolo is the late 19th century and metà del XVIII secolo the mid 18th century. So do the Romanian Începutul, mijlocul and Sfârșitul: Sfârșitul secolului al XIX is the late 19th century and Începutul sec. XX the early 20th century. The Portuguese Início, Meados and Final work in front of a century too, as do the Spanish Inicio and Final: Início do século XX is the early 20th century, Meados do século XIX the mid 19th century and Final del siglo XIX the late 19th century. Mitad de la década de 1970 and A mediados de la década de 1990 are read as the mid 1970s and mid 1990s. In Spanish you can leave out the word siglo after del: Principios del XX is the early 20th century, Finales del XIX the late 19th century and Primera mitad del XVIII the first half of the 18th century. Spanish decades of a century in the plural work the same way: Primeras décadas del siglo XX is the early 20th century, Últimas décadas del siglo XIX the late 19th century and Décadas centrales del siglo XVIII the mid 18th century. With a count they name exact years instead, as long as the end date is left empty: Últimas dos décadas del siglo XX runs from 1980 to 1999 and Tres primeras décadas del siglo XX from 1900 to 1929.
  • Half of a century works the same way, and is also marked approximate: First half of the 20th century runs from 1900 to 1949 and Second half of the 20th century from 1950 to 1999. Latter half reads as the second half, and so do the Spanish Primera mitad del siglo XX and Segunda mitad del siglo XIX and the French Première moitié du 20e siècle and Seconde moitié du XVIe siècle, the Italian Prima metà del XX secolo and Seconda metà del XIX secolo, and the Russian Вторая половина 19 века and Ukrainian Перша половина 19 століття. A Spanish mitad with no ordinal, as in Mitad del siglo XX, is the middle of the century, like mid 20th century. A year can be split in half too, as long as the end date is left empty: 1st half of 2023 runs from January to June 2023, and Segunda mitad de 1990, Seconda metà del 1913 and Seconde moitié de 1968 run from July to December of their year. The Russian and Ukrainian halves of a year work the same way, with or without the word for year: Первая половина 1990 runs from January to June 1990 and Вторая половина 2010 года from July to December 2010. A decade splits into halves of five years, again with the end date left empty: First half of the 1990s runs from 1990 to 1994 and 2nd half of the 2010s from 2015 to 2019. The Spanish Segunda mitad de la década de 1980 (1985 to 1989), the French Seconde moitié des années 1960, the Italian Prima metà degli anni 1960 and the Russian Вторая половина 1940-х гг. work the same way.
  • To mark a date as approximate as you type it, start it with ~ or ≈ (a space after either is fine, as in ≈ 1861) or write c., ca., circa, approx. or around before the year. c. 1450 saves as 1450 with Approx. checked. The Spanish aprox. and hacia, the French vers and environ, the Russian около and примерно, the Ukrainian близько, the Greek περίπου, the Arabic حوالي, the Persian حدود and the Hindi लगभग work the same way. The words circa, ca., approx., aprox. and environ can also follow the year, so 1250 circa, 1500 ca., 1600 aprox and 1850 environ are approximate too. A single c. after the year is not read this way, since it can also stand for a century.
  • A negative year such as -3000 is saved as 3000 BC, in either date field. A minus sign works in a full date too: Nov 28, -0099 saves as Nov 28, 99 BC, 11/28/-0099 as 11/28/99 BC, and the ISO-style -3100-01-01 as January 1, 3100 BC. An ISO-style date can also take the era after it, as in 3100-01-01 BC. Astronomical and ISO 8601 data count a year 0, so -3000 in those sources means 3001 BC. Enter such years one lower (-3001) or type the BC year directly to keep them exact.

We also recognize month names in a number of other languages, along with era markers written the way other languages write them. In place of BC: the Spanish a. C. and a. de J.C., the French av. J.-C., the Norwegian f.Kr., the Dutch v.Chr., the Polish p.n.e., the Greek π.Χ., the Russian до н.э., the Ukrainian до н.е., the Romanian î.Hr., the Bulgarian пр.н.е., the Croatian pr. Kr., the Slovenian pr. n. št., the Czech př. n. l. and Slovak pred n. l., the Turkish M.Ö., the Kazakh б.з.д., the Arabic ق.م. or قبل الميلاد (332 ق.م. is 332 BC), the Persian قبل از میلاد or پیش از میلاد, the Hindi ईसा पूर्व or ई.पू. (232 ईसा पूर्व is 232 BC) and the Hebrew לפנה"ס or לפני הספירה. In place of AD: the Spanish d. C., the French ap. J.-C., the Dutch n.Chr., the Polish n.e., the Greek μ.Χ., the Russian н.э., the Romanian d.Hr., the Bulgarian сл.н.е., the Czech and Slovak n. l., the Turkish M.S., the Kazakh б.з., the Arabic م or ميلادي, the Persian میلادی, the Hindi ईस्वी or ई० and the Hebrew לספירה or לסה"נ. The Turkish M.Ö. and the Arabic markers can also go before a year on its own, as in M.Ö. 71 or قبل الميلاد 500 (500 BC). The Turkish M.S. and the Kazakh markers only work before the year, so write M.S. 1453 or б.з. 476 rather than 1453 M.S. The Russian and Ukrainian word for year after a number is dropped, so 1812 год, 12 октября 1492 г., 1605 рік and a range written 1941-1945 гг. all work. Before an era the short г. can lose its dot, so 4000 г до н.э is 4000 BC and 815 г н.э is the year 815. The Polish word for year at the end of a date is dropped the same way, so 19 czerwca 1754 roku and 1754 r. work too. If yours is not covered yet, drop us a note at [email protected] and we would be happy to add it.

Dates written the Chinese, Japanese or Korean way work too: a full date such as 1939年9月1日 or 2023년 1월 1일, a year and month such as 1555年8月 or 1950년 6월, or a year on its own such as 1908年. To mark the era, put 公元前, 紀元前, 前 or 기원전 before a year on its own for a year BC (公元前27年 is 27 BC), or 公元 or 기원후 for a year AD. Vietnamese dates that write the month as a number after tháng work as well, either in full, as in 30 tháng 4 năm 1975 or Ngày 12 tháng 4 năm 1744, or as a month and year, as in Tháng 10, 1917. Arabic-Indic digits are read as the same digits, so ٣٠ يونيو ٢٠٢٣ is June 30, 2023, and the Arabic comma counts as a comma, so 7 ديسمبر، 1941 is December 7, 1941. Persian digits such as ۱۳۵۷ are read only when a Gregorian era or a Gregorian month name goes with them, as in ۲۰۲۴ میلادی or ۱۵ آوریل ۲۰۲۴ (April 15, 2024). On their own, or with a Solar Hijri month as in بهمن ۱۳۵۷, they usually carry a Solar Hijri year, which would save about 621 years early, so they are not read. Hijri dates such as 17 رمضان، 2 هـ are not read either. Gregorian month names written in Hindi, Marathi or Nepali work with Western digits, as in 15 अगस्त 1947 or जनवरी 31, 1972, as do the short Hindi forms such as 17 सितं 1924 or 19 अग॰ 2026, but Hindu and Nepali calendar months such as बैशाख are not read. Gregorian month names in Hebrew work spelled out, including with the prefix ב that a Hebrew date usually adds (14 במאי 1948 is May 14, 1948) or the prefix ל (20 ליולי 2023 is July 20, 2023), or abbreviated, with or without the prefix and with or without a period or geresh after the short name, as in ספט 11, 2001, 17 בפבר. 1963 or 17 בפבר׳ 1963. Hebrew calendar months such as ניסן are not read. Myanmar digits are read in a year-month-day date such as ၁၈၅၃-၀၁-၀၁ (January 1, 1853), and Gregorian month names in Myanmar script work with either kind of digit, as in မတ် ၁၅, ၁၉၈၅ (March 15, 1985) or ဇန်နဝါရီ 15, 2023. A Myanmar-digit year on its own, such as ၁၃၈၆, is not read, since it may be a Burmese Era year, which would save about 638 years early. Bengali is handled the same way: Gregorian month names in Bengali script work with either kind of digit, as in মার্চ 26, 1971 or ১৬ ডিসেম্বর, ১৯৭১ (December 16, 1971), as do short forms such as সেপ্ট 2014, and Bengali digits are read in a year-month-day date such as ১৯৮৯-০১-০৫ (January 5, 1989). A Bengali-digit year on its own, such as ১৪৩১, is not read, since it may be a Bengali calendar year, which would save about 593 years early, and Bengali calendar months such as বৈশাখ are not read either.

Time Formats

Once a date is specified, you can add a time to it:

  • May 8, 2022 1pm (pm and PM both work)
  • May 8, 2022 1:23pm
  • May 8, 2022 1:23:05pm
  • May 8, 2022 13:23:05 (when no AM or PM is specified, it's assumed to be 24 hour time)

The time can also go before the date, as in 9:45PM Jul 14, 1993 or 8:12 AM, December 7, 1941, as long as it has a colon or an AM or PM and the date spells out its month.

Durations

For event end dates, you can enter a duration instead, which Preceden adds to the event's start date. A few examples:

  • 2 seconds
  • 8 minutes
  • 5 hours
  • 3 days
  • 7 weeks
  • 9 months
  • 1 year
  • 2 years 8 months 1 day 5 minutes
  • 10 weekdays - Preceden skips weekends when working out the end date. When the start date has no time on it, the start day itself counts as the first weekday, so an event that starts on a Monday and runs 10 weekdays ends at the end of the second Friday.

Weekdays have two rules of their own. The number has to be between 1 and 364, and weekdays cannot be mixed with other units, so 1 month 3 weekdays is rejected. The other units combine with each other freely, as in the example above.

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