Date Difference Calculator
How long is it between two dates? Choose a start and an end date and get the difference in years, months and days, together with the total number of days, weeks, months and weekdays, and the same span in hours, minutes and seconds. Tick one box to count both the first and the last day.
- Runs in your browser
- No sign-up
- Free to use
How to use Date Difference Calculator
- Choose the start date, or press Today.
- Choose the end date.
- Tick “Include the end date” if both days count.
- Read the difference and the totals.
Date Difference Calculator features
Years, months and days
Calendar difference counted the way people do: full months first.
Totals
Days, weeks, whole months, hours, minutes and seconds.
Weekdays
Number of Monday-to-Friday days in the span.
Inclusive option
Counts both the start and the end date.
Calendar-correct
Leap years and different month lengths are handled.
Either order
Works when the end date is earlier than the start.
When to use Date Difference Calculator
- Counting days until a deadline, trip or event.
- Working out the length of a contract or notice period.
- Calculating how long ago something happened.
- Checking a period for an invoice or report.
Date Difference Calculator FAQ
Does the result count the end date?
By default it counts the days from the start to the end, the way a calendar measures elapsed time: 1 March to 2 March is one day. Tick “Include the end date” to count both days, which gives two.
How are months counted?
Full calendar months are counted first, from the start day to the same day in later months, and the days left over are added. 31 January to 28 February is 28 days, because February has no 31st.
Are leap years included?
Yes. Dates follow the Gregorian calendar, including 29 February in leap years.
What are weekdays here?
Monday to Friday. Public holidays are not excluded; the Business Days Calculator handles holidays and other weekend patterns.
Why do hours not match local clock changes?
Days are counted as 24 hours. A day on which clocks change for daylight saving actually has 23 or 25 hours.
Is there a date limit?
Dates from year 1 to year 9999 are supported.
Counting time between dates
Counting the days between two dates sounds trivial until months of different lengths, leap years and the question of whether to count the last day get involved. People get it wrong often enough that “off by one” is a standard phrase in programming.
The total number of days is unambiguous once you decide whether the end date counts. Elapsed time, how much time has passed, excludes it: from Monday to Tuesday is one day. Inclusive counting, how many days are covered, includes both ends: Monday and Tuesday are two days. Contracts, hotel stays and leave requests use different conventions, so the calculator offers both.
Months are harder because they vary from 28 to 31 days. The common way to express a span in months is to count whole months from the start date and then the remaining days, which is what the calculator does. That is also why “one month” from 31 January ends at the end of February.
For anything with legal or financial consequences, check how the relevant rule defines its periods. Notice periods, interest calculations and statutory deadlines may count calendar days, business days or months in specific ways, and the definition in the document always prevails.