Date Add/Subtract Calculator
Add or subtract years, months, weeks, days, and time from a local date with calendar-aware handling.
Enter a local start date and the calendar or time amount to add or subtract. The calculator stays on this page and is useful for planning deadlines, renewals, billing windows, content calendars, reminders, and quick future-or-past date checks.
Use your local calendar and clock. Seconds are optional in most browsers.
Choose whether the amount moves forward or backward from the start value.
Controls cases such as January 31 plus one month.
Use the order that matches your contract, schedule, or planning convention.
How it works
The calculator applies the signed amount to the local start date using the selected order. Years and months are calendar units, so their result depends on the target month and leap years. Weeks, days, hours, minutes, and seconds are then applied as local calendar and clock changes.
Month-end handling is important because not every month has the same number of days. Clamp mode moves to the last valid target day when needed. Preserve-end mode keeps dates that start on the last day of a month on the last day after year or month changes. Reject mode stops when the requested month does not contain the original day-of-month.
Daylight-saving changes and local time-zone rules can make elapsed hours differ from simple calendar-day counts. Use the result as a local planning calculation, and verify legal, payroll, travel, or time-zone-sensitive deadlines against the rules that apply to your situation.
