Add or subtract days, weeks, months and years from a date
Find the date a number of days, weeks, months or years before or after a starting date, with its weekday and ISO week number.
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Adding months uses the last available day when needed: 31 January plus one month is 28 February, or 29 February in a leap year. Calculations use UTC.
How to use
- Choose the start date and direction. Select Add or Subtract, then enter a positive whole-number amount.
- Choose the unit. Days and weeks count elapsed calendar days. Months and years follow the calendar rather than using a fixed number of days.
- Read the resulting date. 31 January 2026 plus one month is 28 February 2026. Plus 30 days is 2 March 2026.
Questions
What happens when a month has fewer days?
The result uses the last day of that month. Adding one month to 31 January gives 28 February in 2026, or 29 February in a leap year. Adding one year to 29 February also uses 28 February when needed.
How do the hours and minutes options work?
They count from midnight UTC at the start of the chosen date, but the result shows only a date, not a time of day. Adding 12 hours stays on the same date; subtracting one hour moves to the previous date. Fractional amounts are truncated to whole units.
Can I exclude weekends and holidays?
This page counts calendar time in UTC. Use the business-days calculator for a working-day offset and select the weekend pattern and any holidays that apply.
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