About this calculator
Days and weeks are added on the calendar directly. Months and years keep the same day of the month; if that day doesn’t exist (adding a month to 31 January), the last day of the month is used instead.
Worked example
90 days after 4 November 2026 is Tuesday, 2 February 2027. One month after 31 January 2026 is 28 February 2026.
How to use the date calculator
- Enter the start date.
- Choose the add or subtract.
- Choose the unit.
- Enter the amount.
- Read the result — it updates as you type.
Frequently asked questions
What is 90 days from today?
Leave the start date as today, choose Add, Days and 90.
What happens when I add a month to 31 January?
You get the last day of February, because February has no 31st.