Date-time converter
Convert date and time into the various different formats
About Date-time converter
The same instant is written differently across systems: Unix timestamps, ISO 8601, RFC 3339, Excel serial numbers, MongoDB ObjectIDs. This tool detects what you paste in and prints every common format at once, in the timezone you choose.
When you would use it
- Seeing a bare number in a log line or an API response and wanting to know what time it represents.
- Needing a specific format to write into a config file or a database.
- Working across timezones and wanting to know what a given instant is for the other side.
- Recovering dates from an Excel export where they turned into decimal numbers.
How to use it
- Paste the value into the input; the format is detected and the selector switches automatically.
- If detection gets it wrong, pick the input format manually in the selector on the right.
- Choose a timezone; every output is converted accordingly.
- Use the copy icon next to a field to take the result.
Things worth knowing
- An input without an offset (for example 2023-04-12 23:10:24) is read in the timezone you selected. An input with an offset (ending in Z or +08:00) keeps that offset and ignores the selector.
- Unix timestamps come in seconds and milliseconds; ten digits is usually seconds, thirteen is milliseconds. The tool decides from the digit count.
- The Excel serial value counts days since 1900, and the fractional part is the time of day.
Frequently asked questions
- What if I need to convert many timestamps at once?
- Use the timestamp batch converter, which takes many values at once and prints them as a table.
- What is the difference between ISO 8601 and RFC 3339?
- RFC 3339 is effectively a strict subset of ISO 8601: it requires a T between date and time and always requires a timezone offset. For APIs and config files, RFC 3339 is the safer choice.