Add Days to a Date
Pick a date and how much time to add.
How it works
- Pick a start date.
- Enter how many days, weeks, months or years to add.
- See the resulting date and its day of the week.
Frequently asked questions
What happens when adding a month to 31 January?
The result is clamped to the last day of the shorter month, so 31 January + 1 month = 28 February (or 29 in a leap year).
Is the start date counted as day one?
No. Adding 1 day to Monday gives Tuesday. Count one day less if your contract counts the start date as day one.
Can I calculate a date in the past?
Yes — switch the operation to Subtract, or use the Subtract Days from Date tool.
Do time zones affect the result?
No. Dates are treated as whole calendar days, so daylight saving changes don't shift the answer.
Date arithmetic without the calendar
Find the date 30, 60 or 90 days from today — for invoices, trials, warranties, notice periods or countdowns — or add weeks, months and years.
Months have different lengths
Adding months keeps the same day of the month where possible and clamps to the month's last day otherwise, which matches how most contracts and billing systems work.