How to use the Add or Subtract Days from a Date
- Pick the start date.
- Choose add or subtract and enter years, months, weeks or days.
- Read the resulting date and weekday.
About this tool
Use it for due dates and deadlines: payment terms (“net 45”), 90-day return or warranty windows, notice periods, visa stays, medicine courses or the date 180 days after a policy starts. Years and months are added first, then weeks and days.
When you add months to a date near the end of a month, the result is clamped to the last valid day — 31 January plus one month gives 28 February (29 in a leap year). With “Count days as working days”, weekends are skipped; public holidays are not.
Frequently asked questions
What date is 90 days from today?
Leave the start date as today, enter 90 in Days and the result shows instantly. Use the quick buttons for 30, 60, 90 or 180 days.
Is the start date counted as day 1?
No. Adding 1 day to Monday gives Tuesday — the same as calendars and Excel. Subtract one day if your rule counts the start date.
How do I add business days?
Tick “Count days as working days”. Saturdays and Sundays are skipped (or only Sundays with the 6-day option).