Add days to a date
Find the date a given number of days after a start date, such as the end of a notice period, trial or validity.
Loading the tool…
Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter start date and number of days.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Result = start date + number of days, rolling over months and years by the real month lengths and leap years.
Example
Inputs: Start date = 2026-10-01, Number of days = 100 days. Result: Resulting date: Saturday, January 9, 2027 (2027-01-09); Day of the week: Saturday; Difference in days: 100.
Limits and caveats
- Counts calendar days including weekends; use the add business days tool for working days.
Questions about this tool
Is the start day counted?
No, adding 1 day to 1 October gives 2 October.
How do I find the end of a 90 day period?
Enter the day the period starts and type 90 to see the end date and its weekday.
Can I add very large numbers?
Yes, thousands of days work as long as the result stays before the end of year 9999.