Count the days, weeks, months, years and weekdays between two dates, or add and subtract time from a date.
By default the start date is not counted and the end date is, so Monday to Friday is 4 days. Tick the box to count both.
This tool does the two date jobs people most often work out by hand. The first is finding how much time sits between two dates, in days, weeks, months, years and weekdays. The second is finding the date you land on after adding or subtracting days, weeks, months, years or business days. It uses real calendar dates, so leap years and months of different lengths are handled for you, and daylight saving time never shifts the answer by a day. Everything runs in your browser.
Use date difference when you have two dates and want the gap between them. Typical uses are counting down to an event, checking how long a project ran, or working out how many days are left before a deadline. Use add or subtract time when you have one date and a length of time. Examples include "an invoice is due 30 days after March 3", "12 weeks before the deadline", or "10 business days from today".
By default, the calculator counts the end date but not the start date. That is how most contracts, deadlines and "days since" questions are read: from Monday to Friday is 4 days, not 5. Some situations count both ends. A hotel stay from the 10th to the 14th is 4 nights, while a conference running from the 10th to the 14th is 5 days. If you need both ends counted, tick the box and the total goes up by one. The weekday counts adjust with it.
The years, months and days figure is calendar-aware. It counts whole calendar months from the start date, and whatever remains becomes days. It is not the total number of days divided by 30 or 365, which is why the months shown will not always match a rough division. When the start day does not exist in a later month, the calculator uses the last day of that month. So January 31 plus one month is February 28, or February 29 in a leap year, and January 31 to March 1 is 1 month and 1 day.
From January 15, 2020 to September 16, 2026 is 6 years, 8 months and 1 day, or 2,436 days, which is exactly 348 weeks. A shorter range shows the weekday count. From March 2 to March 27, 2026 is 25 days, and 19 of them are weekdays. From January 1 to September 16, 2026 is 258 days and 184 weekdays. Adding 45 days to September 16, 2026 lands on Saturday, October 31, 2026, and adding 90 days to January 15, 2026 gives Wednesday, April 15, 2026.
Pick Business days as the unit to skip Saturdays and Sundays. Ten business days from Friday, September 4, 2026 is Friday, September 18, 2026, which is 14 calendar days later. Thirty business days from Monday, September 21, 2026 lands on Monday, November 2, 2026. Keep in mind that the calculator skips weekends only, not public holidays. Labor Day, September 7, 2026, would push the first result out by one more working day in practice. If a deadline is counted in working days, add the holidays that apply to you by hand or check the wording of the agreement.
A leap year has 366 days. Years divisible by 4 are leap years, except century years such as 1900 and 2100, which are leap years only when divisible by 400. So 2028 has 366 days and 2026 has 365. The calculator counts February 29 whenever it falls inside your range. Adding one year to February 29 in a non-leap year lands on February 28.
Does this count the start date, the end date, or both?
By default the end date is counted and the start date is not, which matches how most deadlines and "days since" questions are read. A gap from Monday to Tuesday is 1 day. Tick the box to count both dates, which makes Monday to Tuesday 2 days.
How does it handle leap years?
Automatically. The day total, the weekday count and the years, months and days breakdown all use real calendar dates, so a February 29 in the range is counted correctly with no extra input from you.
Why do the months shown not match total days divided by 30?
Real months are not 30 days long. The calculator counts whole calendar months, which run from 28 to 31 days, and shows the leftover as days, so it will not line up with a flat 30-day estimate.
Can I add or subtract months or years, not just days?
Yes. In add or subtract mode, choose weeks, months or years as the unit. Months and years are added calendar-style, not as a fixed number of days.
What happens if I add a month to the 31st?
The result lands on the last day of the following month if that month is shorter. Adding one month to January 31 gives February 28, or February 29 in a leap year, not March 3.
Does it skip weekends and public holidays?
The business days option skips Saturdays and Sundays. It does not know about public holidays, which differ by country, state and employer, so remove those by hand if they matter.
Can the end date be before the start date?
Yes. Put the dates in either order and the calculator shows the gap between them as a positive duration, with a note that the dates were swapped.
Can I use this for contract terms or payment deadlines?
Yes, add or subtract mode is built for that. Enter the start date, the term length and the unit to find the exact due date and its weekday. For anything with legal consequences, confirm how your contract or local rules count days, since some exclude weekends or holidays.