Add or subtract any combination of years, months, weeks and days from a start date, with an option to count weekdays only, to find deadlines, notice periods, warranty expiry and due dates.
How to add days to a date
- Choose the start date.
- Choose Add or Subtract and enter years, months, weeks or days.
- Read the resulting date and weekday.
Month-end rule
Adding one month to 31 January gives 28 or 29 February (the last day of the month), not 3 March. This matches how contracts and banks usually treat month arithmetic.
Frequently asked questions
What is 90 days from today?
Leave today as the start date and enter 90 in Days.
How do I count 10 working days?
Tick “Count weekdays only” and enter 10 days.
Updated October 2026 · Built and tested by Sharjeel Tahir · How our tools are tested