Subtract days from a date
Find the date a set number of days before another date, to trace back a start date from a known end date.
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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 and number of days.
- 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
Result = entered date − number of days, stepping back through months and years by their real lengths.
Example
Inputs: Date = 2026-10-01, Number of days = 90 days. Result: Resulting date: Friday, July 3, 2026 (2026-07-03); Day of the week: Friday; Difference in days: 90.
Limits and caveats
- Applies the Gregorian calendar to old dates too, so results may differ from Julian calendar records before 1582.
Questions about this tool
What was the date 30 days ago?
Leave the date on today and type 30 to see it.
Is February handled correctly?
Yes, it uses 28 days, or 29 in a leap year.
How do I find when a period started?
Enter the end date and the period length in days; the result is the start date.