What are these date formats?

The same moment can be written in many ways. People write dates with the day, month and year in the order their country uses, standards fix one way for computers to exchange them, and programs often store a date as a number: how many seconds, days or smaller steps have passed since a starting point, called the epoch.

Here is 3 November 2026 at 14:30 UTC in each format:

Format Example What the value is
ISO 8601 2026-11-03T14:30:00Z Year, month, day and time, with Z for UTC or an offset like +02:00
Unix timestamp 1793716200 Seconds since 1 January 1970, 00:00 UTC
Unix timestamp in milliseconds 1793716200000 Milliseconds since 1 January 1970, as JavaScript's Date.now() gives them
RFC 2822 Tue, 03 Nov 2026 14:30:00 +0000 The date format of email headers, also used by HTTP
YYYY-MM-DD 2026-11-03 14:30 Year, month, day, as databases and many countries write dates
MM/DD/YYYY 11/03/2026 14:30 Month, day, year, as dates are written in the US
DD/MM/YYYY 03/11/2026 14:30 Day, month, year, as dates are written in the UK and much of Europe
Excel serial date 46329.6041666667 Days since the start of 1900, with the time as a fraction of a day
Julian date 2461348.10416667 Days since noon on 1 January 4713 BC, used in astronomy
Modified Julian Date 61347.6041666667 Days since midnight on 17 November 1858, the Julian date minus 2400000.5
Windows FILETIME 134381898000000000 100-nanosecond steps since 1 January 1601, also in LDAP and Active Directory
Chrome timestamp 13438189800000000 Microseconds since 1 January 1601, as Chrome and WebKit store them
Core Data timestamp 815409000 Seconds since 1 January 2001, Apple's reference date, also called Mac absolute time

Tool description

Every date format converter here converts between all of these formats and works the same way, from the general Date Format Converter to the ones for a single pair, such as Unix timestamp to ISO 8601, MM/DD/YYYY to DD/MM/YYYY, or Excel serial date to YYYY-MM-DD: each starts on the formats in its name, and the Source and Target menus switch to any other. It starts on the current time in the source format, so the result shows the time now in the target format.

Paste one date, or a whole list with one per line. The result appears as you type, ready to copy. Each line of the result is the same line of the input converted, and blank lines stay blank, so the rows stay lined up with the ones you pasted. The swap button turns the conversion around and makes the result the new input.

When a line can't be converted, the error says what's wrong with it, and in a list, which line it's on. Dates are converted in your browser.

Examples

Source Input Target Result
Unix timestamp 1793716200 ISO 8601 2026-11-03T14:30:00Z
ISO 8601 2026-11-03T16:30:00+02:00 Unix timestamp 1793716200
MM/DD/YYYY 11/03/2026 DD/MM/YYYY 03/11/2026
DD/MM/YYYY 3.11.2026 YYYY-MM-DD 2026-11-03
MM/DD/YYYY 11/03/2026 2:30 PM ISO 8601 2026-11-03T14:30:00Z
Excel serial date 46329 MM/DD/YYYY 11/03/2026
RFC 2822 Tue, 3 Nov 2026 09:30:00 EST ISO 8601 2026-11-03T14:30:00Z
Julian date 2451545 ISO 8601 2000-01-01T12:00:00Z
Windows FILETIME 130000000000000000 ISO 8601 2012-12-14T23:06:40Z
Unix timestamp 1793716200.5 Unix timestamp in milliseconds 1793716200500

A list converts line by line. These Excel serial dates:

46329
46330.5

46331.75

become these YYYY-MM-DD dates:

2026-11-03
2026-11-04 12:00

2026-11-05 18:00

What you can paste

  • ISO 8601: a date, 2026-11-03, or a date and time, with a T or a space between them, with or without seconds and decimals of a second. A time can end in Z for UTC or an offset such as +02:00, +0200 or -05. The basic format without separators, such as 20261103T143000Z, works too.
  • Unix timestamps, Windows FILETIME, Chrome and Core Data timestamps: a whole number, which can be negative for moments before the epoch, or a number with decimals, such as 1793716200.5.
  • RFC 2822: the day of the week is optional, the year can have two digits, which are read as 1950 to 2049, and the time zone can be an offset such as +0200, or UT, GMT, Z, EST, EDT, CST, CDT, MST, MDT, PST or PDT. A comment after the zone, as in +0000 (UTC), is skipped, so dates copied from email headers work as they are.
  • YYYY-MM-DD, MM/DD/YYYY and DD/MM/YYYY: the year has four digits, and the day and month one or two. A slash, a dot or a dash can separate them, as long as it's the same one throughout, so 3.11.2026 and 03-11-2026 are both DD/MM/YYYY dates. A time can follow, such as 14:30, 14:30:15, 2:30 PM or 2:30 p.m..
  • Excel serial dates, Julian dates and Modified Julian Dates: a number, with a decimal point or a decimal comma, such as 46329.5 or 46329,5.

How it works

Each line is read into a moment in time, down to the nanosecond, then written in the target format. Dates and times without a time zone, and every number format, are read as UTC, and results are written in UTC. To convert a date to another time zone, use the Timezone Converter.

Results are written like this:

  • ISO 8601 always with the seconds and Z, and with decimals of a second only when the moment has them: 3, 6 or 9 digits, for milliseconds, microseconds or nanoseconds.
  • RFC 2822 with the offset +0000. It has no decimals of seconds, so they're left out.
  • YYYY-MM-DD, MM/DD/YYYY and DD/MM/YYYY with the time on a 24-hour clock after the date, but only when it isn't midnight: 11/03/2026 is midnight, and 11/03/2026 14:30 half past two in the afternoon.
  • Unix timestamps, Windows FILETIME, Chrome and Core Data timestamps as whole numbers, or with as many decimals as the moment needs, so nothing is lost: an ISO 8601 date with milliseconds becomes a Unix timestamp like 1793716200.123.
  • Excel serial dates, Julian dates and Modified Julian Dates with up to 15 significant digits, as Excel shows numbers. They're read to the nearest millisecond.

Dates are in the Gregorian calendar, the one used today, also for dates before it was introduced in 1582. The converters work with the years 1 to 9999.

Excel counts a 29 February 1900, a day that didn't exist, because Lotus 1-2-3 did. So the converters read serial date 1 as 1 January 1900 and 61 as 1 March 1900, as Excel does, and show an error for serial date 60. Google Sheets and LibreOffice give the same dates from 1 March 1900 on.

Tips

  • To convert a column of a spreadsheet, copy the column, paste it into the converter and copy the result back next to it: blank cells stay blank, so the rows line up.
  • A Unix timestamp with 13 digits, such as 1793716200000, is in milliseconds. Read as seconds, it lands tens of thousands of years from now and shows an error, so pick Unix timestamp in milliseconds as the source.
  • In an Excel cell that shows a date, switch the cell's format to Number to see its serial date. Workbooks made with older versions of Excel for Mac can use the 1904 date system, whose serial dates are 1462 lower.
  • 18-digit timestamps in Active Directory attributes such as lastLogonTimestamp or pwdLastSet are Windows FILETIME values.