Date calculator
Runs in this page, nothing is sentAdd or subtract days, working days, weeks, months or years from any date, for deadlines, notice periods, due dates and expiry dates. Switch to Days between dates to count the gap between two dates.
Pick the dates.
How to use it
- Pick the start date (today by default).
- Choose Add or Subtract, the amount and the unit, such as 90 days or 3 months.
- Read the resulting date and weekday. For working days, choose your weekend.
Details
- Calendar
- Gregorian, every date from 1900 to 2200, leap years included
- Time zones
- Whole days in plain calendar dates, so time zones and daylight saving never move the answer by a day
- Month ends
- Adding a month to 31 January gives 28 February (29 in a leap year): the last day, never a spill into March
- Working days
- Choose the weekend: Saturday and Sunday, Sunday only, or Friday and Saturday. Public holidays are not removed
Questions
Is anything I type sent anywhere?
No. The calculation runs in this page with JavaScript; dates, text and numbers are never uploaded or stored on a server.
What is 90 days from today?
Enter 90 with Days selected and the date appears with its weekday. 90 days is not the same as 3 months: from 10 November 2026, 90 days is 8 February 2027 and 3 months is 10 February 2027.
How does adding months work at month end?
The day is kept where possible and otherwise moved to the last day of the month: 31 January plus 1 month is 28 February, or 29 February in a leap year.
Does 'working days' skip public holidays?
No, only the weekend you choose. Holidays differ by country, state and company, so subtract them yourself if your deadline excludes them.
Does the start date count as day one?
No: adding 1 day to Monday gives Tuesday. For counting, the Days between dates mode has an option to include the end date.