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.
  • Separate the numbers in a date with slashes or dashes, not periods: 5/8/2022 and 5-8-2022 work, but 05.08.2022 is rejected. A date that starts with the year needs dashes, so use 2022-05-08 rather than 2022/05/08.
  • 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 Dateless Timelines.

Date Formats

  • 2022
  • May 2022
  • 5/2022
  • May 8, 2022
  • May 8th, 2022
  • 5-8-2022
  • 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.
  • 8th of May 2022
  • 8 de Mayo 2022
  • 8 de Mayo de 2022
  • 60,000 BC - We support BC, BCE, BP, FVT, AD, CE, AC, DC, EVT; periods and spaces between the letters are optional.
  • 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. Preceden treats the three 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.
  • You can also enter a decade such as 1940s, which is split into 1940 to 1949 when the event is created.
  • A negative year such as -3000 is saved as 3000 BC, in either date field. 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: the Spanish a. C., the French av. J.-C., the Norwegian f.Kr., the Dutch v.Chr. and n.Chr., and the Polish p.n.e. and n.e. all work in place of BC and AD. If yours is not covered yet, drop us a note at [email protected] and we would be happy to add it.

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)

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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