Date calculator
Find the gap between two dates, or add time to one.
Tuesday
- Years, months and days breakdown
- Counts business days
- Add or subtract days, weeks, months or years
How to calculate with dates
- Pick the difference or add/subtract mode.
- Enter your date or dates.
- Read the days, weeks, months and business days.
A second worked example
From March 10, 2023 to November 22, 2024 is 623 days, which breaks down to 1 year, 8 months and 12 days. Of those 623 days, 445 fall on a weekday.
Counting days across months
| Length | Months | Count |
|---|---|---|
| 31 days | January, March, May, July, August, October, December | 7 months |
| 30 days | April, June, September, November | 4 months |
| 28 or 29 days | February | 1 month |
Because months are not the same length, a 3 month gap can run from 89 to 92 days depending which months it crosses. A leap year adds one extra day to February: a leap year is any year divisible by 4, except a century year, which must also be divisible by 400. That is why 2000 was a leap year but 1900 was not, and why 2024 and 2028 are leap years but 2025, 2026 and 2027 are not.
Common mistakes
- Assuming every month is 30 days when eyeballing a gap by hand. A 3 month span can be 89, 90, 91 or 92 days depending which months it covers.
- Forgetting a leap year inside a multi-year gap, which changes the day total by one for every February 29 it crosses.
- Expecting a business day count to skip public holidays. This tool only excludes Saturdays and Sundays, since holidays differ by country.
- Mixing up the from and to date, which flips the sign of the result instead of just the direction you meant.
Subtracting months near the end of one
The same day-of-month clamping applies going backward. March 31, 2025 minus 1 month lands on February 28, 2025, since February has only 28 days that year, not a nonexistent February 31.
It only clamps when it has to: May 31, 2025 plus 3 months lands cleanly on August 31, 2025, since August also has 31 days.
Date calculator FAQ
How many days are between January 1, 2024 and June 15, 2025?
531 days, which is 1 year, 5 months and 14 days, including 379 business days.
What is 3 months after January 15, 2025?
April 15, 2025, a Tuesday.
What counts as a business day?
Any Monday through Friday. This tool does not exclude public holidays, since they vary by country.
What happens when I add a month to the 31st?
The result lands on the last day of the following month if it is shorter, so January 31 plus 1 month gives February 28 (or 29 in a leap year).
How many days are between March 10, 2023 and November 22, 2024?
623 days, which is 1 year, 8 months and 12 days, including 445 business days.
Can I subtract months or years instead of adding them?
Yes. Switch the operator to subtract and pick days, weeks, months or years. For example, 6 months before September 24, 2025 is March 24, 2025.
Can I find the number of weekend days between two dates?
Subtract the business day count from the total days. For the March 10, 2023 to November 22, 2024 example, that is 623 minus 445, or 178 weekend days.
Does the years, months, days breakdown ever look different from what I expect?
It can, because months are counted from the day of the month, not a fixed 30-day block. January 15 to March 10 is 1 month and 23 days, not 1 month and 25 days, since the day-of-month count (15 to 10) rolls back a day before the month count increases.