Calculator: Add or Subtract Days from a Date
Find the date after adding or subtracting days, weeks or months.
Tip: You can add weeks and months too — not just days.
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About this digital tool
The add or subtract days calculator finds the date that results after a given number of days, weeks or months. Choose the starting date, decide whether to add or subtract, enter the amount and the unit and get the new date, together with the day of the week.
Weeks are counted as 7 days, while months follow the real calendar: when the day of the month doesn't exist in the new month, e.g. 31 January plus 1 month, the result adjusts according to calendar rules. It is useful for payment and contract deadlines, expiry dates, trial periods, warranty periods and event planning. For legal deadlines, check how the start of the period is counted in the relevant document.
How to use
- Choose the starting date.
- Set the number of days/weeks/months to add or subtract.
- See the final date.
Frequently asked questions
How does adding months work?
The number of months is added keeping the day of the month. E.g. 31 January + 1 month = 28/29 February (the last day). If the month doesn't have that day, the last day is used.
How do I find the date after 90 days?
Choose the start date, choose 'add', enter 90 and choose days. The tool gives the date and the day of the week.
What happens when I add months to a date like 31 January?
Since February doesn't have 31 days, the result adjusts according to calendar rules and falls on the nearest valid day. Check the result when the start date is at the end of a month.
Can I subtract days from a date?
Yes, choose the 'subtract' operation. It is useful for finding a date in the past, e.g. when a deadline started.