Date Add/Subtract Calculator

How date arithmetic works

Adding days is straightforward — just move the calendar forward. Adding months adjusts the month component and keeps the day (or clamps to the last day of the target month for overflow, e.g. Jan 31 + 1 month = Feb 28/29). Adding years follows the same rule — Feb 29 + 1 year = Feb 28 in a non-leap year. All calculations use UTC to avoid timezone edge cases. Related: date difference calculator and business days calculator.