This calculator adds or subtracts calendar time from a date for deadlines, schedules, renewals, and other things dates make unnecessarily fiddly.
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Enter a starting date, choose add or subtract, then enter the number of days, months, or years. If available, select whether weekends or specified holidays should be excluded.
For days, result date = start date + or - the selected number of calendar days. Months and years are shifted by calendar units, with an end-of-month date adjusted to the last valid day when the target month lacks that day.
Adding one month to January 31, 2025 gives February 28, 2025 because February has no 31st. Adding another 10 days gives March 10, 2025.
Standard date addition starts counting after the starting date, so one day after April 10 is April 11. Deadline rules sometimes count inclusively, so confirm the convention being used.
They are included in calendar-day calculations. Exclude them only when using a business-day option, and remember that holiday treatment depends on the selected holiday list.
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