Add or subtract days
Find the date a set number of days, weeks, months or years from another.
Result
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Fill in the fields to see the result.
How it works
Years and months are applied first, then weeks and days. Adding a month keeps the same day number in the next month, so 10 March plus one month is 10 April.
If that day does not exist, the date moves back to the last day of the month: 31 January 2026 plus one month is 28 February 2026. Adding the days afterwards is then exact.
Calendar days moved shows the real distance between the two dates.
Formula
1. Add or subtract years × 12 + months, keeping the day (or the last day of the month) 2. Add or subtract weeks × 7 + days
Worked example
19 October 2026 plus 30 days is 18 November 2026, a Wednesday. 31 January 2026 plus 1 month is 28 February 2026, because February 2026 has 28 days.
Questions people ask
What is 31 January plus one month?
The last day of February: 28 February, or 29 February in a leap year. Most calendars and spreadsheets use this rule.
Is adding 4 weeks the same as adding a month?
No. Four weeks is always 28 days, while a month is 28 to 31 days depending on the month.
Can I skip weekends?
Use the business days calculator to add working days only.