Add / Subtract from a Date
Find a date a number of days, weeks, months, or years before or after another date.
Last updated
How to add or subtract days from a date
- Pick the starting date.
- Choose Add or Subtract, type the amount and choose days, weeks, months or years.
- Read the resulting date and its day of the week.
About this tool
Days and weeks are added as exact 24-hour calendar days. Months and years shift the calendar month/year directly and then clamp the day if the target month is shorter — adding 1 month to 31 January lands on 28 February (or 29 in a leap year), not 3 March, matching how most calendar apps handle month-end dates.
Nothing entered here is sent to a server — the entire calculation runs as JavaScript in your browser tab.
Questions about date calculations
What date is 90 days from today?
Leave the starting date as today, choose Add, type 90 and choose Days. It’s useful for notice periods, return windows and visa stays.
What happens when I add a month to 31 January?
You get 28 February (or 29 in a leap year), not 3 March. If the target month is shorter, the date moves to its last day, as most calendar apps do.
Is adding 4 weeks the same as adding 1 month?
No. 4 weeks is always exactly 28 days, while a month is 28 to 31 days. Choose the unit your deadline actually uses.
Can I work out a date in the past?
Yes. Choose Subtract, for example to find the date 6 weeks before an event.