Add Days Calculator

Add any number of days, weeks, months or years to a date to find the future date and weekday.

What is the Add Days Calculator?

Useful for due dates, validity periods, return windows and follow-ups — “what date is 90 days from today?”.

How does it work?

Days and weeks are added exactly. Months and years keep the same day of month where possible, falling back to the month’s last day (31 January + 1 month = 28 February).

Formula

Result = Start + N days

Example

90 days after 27 September 2026 is Saturday, 26 December 2026.

Frequently asked questions

Does adding 1 month always add 30 days?

No. It moves to the same date next month, which can be 28 to 31 days later.

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