Add or subtract days from a date
Quickly calculate a date by adding or subtracting a number of days from a starting date (for example for a 30-day deadline or a date 90 days ago). 100% local processing in your browser (WebAssembly) — nothing is sent to a server.
How it works
Whether it's for calculating a 30- or 60-day payment deadline, a return date after a withdrawal period, a future anniversary date, or a past date (by entering a negative number of days), it's easy to make mistakes counting by hand because of months of different lengths and leap years. This tool performs this calendar calculation reliably and instantly.
How do I subtract days instead of adding them?
Simply enter a negative number in the "days to add" field (for example -15 to go back 15 days): the result will be the date 15 days before the starting date.
Does the calculation account for leap years?
Yes, the tool uses a standard Gregorian calendar algorithm that correctly handles leap years (including the special rules for century years such as 1900 or 2000).
100% local processing: the calculation happens entirely in your browser via WebAssembly — your dates are never sent to a server.