Add or subtract days from a date
Pick a start date, say how much to add or subtract, and get the resulting date with its day of the week right away.
Choose the start date and how much you want to add.
End-of-month adjustment
The destination month does not have that day, so the result is the last day of that month.Estimated or incomplete holidays
Common time frames
Calendar days, without excluding weekends or holidays.
How it is calculated
- Formula
—- With your values
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The start date does not count as an elapsed day. Dates are handled as calendar days, with no time zones or daylight saving time.
How to use it
- Enter the start date as mm/dd/yyyy or pick it from the calendar. The “Today” button uses the current date.
- Choose whether to add or subtract, and fill in the years, months, weeks, or days. You can combine them, or tap a shortcut like “30 days”.
- Read the resulting date with its day of the week and how many calendar days separate the two dates.
- Check the table of common time frames to see at a glance the date in 7, 30, 60, or 90 days. With “Count business days only”, weekends and holidays are skipped.
Frequently asked questions
Is the start date counted?
No. Adding 1 day to a Monday gives Tuesday: the start date is the starting point and does not count as an elapsed day. If your legal or contract deadline counts the first day, subtract 1 from the result.
What happens if I add a month to January 31?
The destination month does not have a 31st, so the result is the last day of February (28 or 29). We let you know when this adjustment happens.
In what order are years, months, weeks, and days added?
Years and months are added first, with the end-of-month adjustment, and then the weeks and days. Subtracting works in the same order.
Can I count business days only?
Yes. Turn on “Count business days only” and weekends and U.S. federal holidays are skipped. The holiday calendar covers 2025 to 2027; for other years only holidays that fall on a fixed date are estimated, so double-check important deadlines.
Does it work with leap years?
Yes. February 29 is taken into account: for example, 365 days after January 1, 2028 is December 31, 2028, because 2028 is a leap year.
Are my dates saved?
No. The calculation happens in your browser and nothing is sent to a server. The share link contains only the values you choose to copy.
How to add days to a date
Adding days means moving forward on the calendar by a number of calendar days, counting Saturdays, Sundays, and holidays. From September 29, 2026, 30 days later is October 29, 2026.
Months and years
Months are not all the same length, so adding a month is not the same as adding 30 days. Adding a month to January 15 gives February 15; adding it to January 31 gives February 28 (29 in a leap year), the last day of the month.
Common time frames
- 30 days: invoice due dates, trial periods, and warranties.
- 60 and 90 days: payment terms, return windows, and contracts.
- 180 and 365 days: renewals, expirations, and updates.
Subtracting days
Subtracting helps you find out when something started or how far back to go: what the date was 90 days ago, or when a deadline that ends on a given date began to run.
Updated on September 29, 2026