Add or subtract days from a date
Enter a starting date and a number of days to add or subtract. The result is the new date. Use a negative number to go back in time. Useful for deadlines, scheduling, and planning.
How it works
All date arithmetic uses the browser's native Date object. Day differences are computed by subtracting timestamps and dividing by 86,400,000 ms. Age counts complete calendar months, shown as years and months, then the days since the last monthly anniversary. The page does not call any external library or server during the calculation. Dates are read at local noon in your browser's time zone, so a daylight saving change from the IANA rules built into the browser never moves a count to the wrong day.
Processing runs in your browser
All calculations happen instantly in your browser tab. Our servers are not involved at any point.
Related operations
For working out an exact age in years, months, and days, try the age calculator. To convert any timestamp into a date, use Unix timestamp. For scheduling work across time zones, see the timezone converter.
Frequently asked questions
- What date is 90 days from today?
- Enter today's date and 90 in the days field to find the date 90 days from now. The tool calculates it automatically.
- Can I subtract days from a date?
- Yes. Enter a negative number to go backward. For example, −30 will give you the date 30 days before the selected date.
- Does it account for leap years?
- Yes. The calculation uses the browser's native Date object, which handles leap years, month lengths, and all calendar rules automatically.
- Can daylight saving shift the result by a day?
- The start date is taken at local noon and whole calendar days are added, so a clock change in between cannot move the result to the wrong day. For example, 30 September 2026 plus 90 days is 29 December 2026.
Last reviewed September 30, 2026
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