Use this date calculator to find the exact date after adding or subtracting a number of days, weeks, months or years from a chosen starting point. It is useful for project deadlines, subscription renewals, invoice due dates, contract end dates, travel planning and any situation where you need to know a future or past calendar date quickly.
When adding months to a day that doesn't exist in the target month (e.g., January 31 + 1 month = February 31, which doesn't exist), JavaScript automatically adjusts to the last valid day of that month (March 3 in a non-leap year).
Yes — use the "Subtract" operation to go back in time. You can also set any start date (past or future) and add or subtract from it.
Because calendar months do not all have the same number of days. When the target month is shorter than the starting month, the result is adjusted according to calendar rules.
Method: Start with the selected date, then apply the amount in the chosen unit using standard calendar arithmetic. Adding months/years accounts for different month lengths.
Example: Start date: March 21, 2026. Add 90 days → Result: June 19, 2026 (90 days, 12 complete weeks).
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