Date Add & Subtract Calculator
Add or subtract days, weeks, months or years from any date
Instructions
Date Calculator Instructions\n\n## What It Does\nStarting from any date, work out dates like "30 days from now", "3 months ago" or "1 year later" — handy for contract expiry dates, billing dates, leave days and project milestones.\n\n## How to Use\n1. Pick a start date (today by default)\n2. Choose "after" or "before", enter an amount, then pick a unit (days / weeks / months / years)\n3. Or just click a shortcut button below, such as +30 days or +3 months\n4. The result area shows the result date, the weekday, and how many days apart the two dates are\n\n## Notes\n- When counting by months, if the target month has no such day, the tool uses the last day of that month — for example 31 January plus 1 month = 28 February (29 in a leap year), and a note appears below the result\n- Results are calculated in your local time zone, so there is no off-by-one-day shift across time zones\n- Everything runs in your browser; no data is uploaded
FAQ
Why is 31 January plus one month 28 February?
Because February has no 31st. The tool clamps the day to the last day of the target month and clearly notes below the result that this adjustment was made.
Does this count calendar days or working days?
Calendar days, including weekends and holidays. If you only want working days, use the working day calculator.
Do leap years or daylight saving time affect the result?
Leap years are handled correctly according to the calendar. Results are based on date objects in your local time zone, so a daylight saving switch will not shift the result by a day.
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