Unix epoch day number
Useful for developers and data analysts who store dates as day counts, as the Parquet DATE type and some databases do.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter date.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Day number = days from 1970-01-01 to the date, negative before 1970. Timestamp in seconds = day number × 86400, in milliseconds = day number × 86400000.
Example
Inputs: Date = 2000-01-01. Result: Day number since 1970-01-01: 10,957; Weekday: Saturday.
Limits and caveats
- The timestamp is for the start of the day in UTC, not your local time.
- Unix time ignores leap seconds, as the standard itself does.
Questions about this tool
What is the Unix epoch day number?
The count of whole days since 1 January 1970, so 1 January 2000 is day 10957.
Why is the number sometimes negative?
Dates before 1970 sit before day zero, so 31 December 1969 is day -1.
How do I get the date back from the day number?
Multiply it by 86400000 for milliseconds, pass that to new Date in JavaScript and read the date in UTC.