Understanding the result
The large figure is the absolute duration: the exact number of days from one date to the other. Use it when you need a count, such as days on a contract, days since an event or days remaining until a deadline.
The line beneath it is the calendar difference, written as years, months and days. Months are not a fixed length, so this breakdown answers "how many whole months and leftover days" rather than "how many days". Weeks, hours and minutes are derived from the exact day count, using 24-hour days.
What is a date difference calculator?
A date difference calculator measures the gap between two calendar dates. It is the tool behind questions such as "how many days between 1 March and 18 July?" or "how long have I been in this job?".
It works on whole dates with no time of day. If you need to include hours and minutes or compare moments in different time zones, the time zone tools are the better fit.
How it works
Each date is converted to a day number on the proleptic Gregorian calendar. The absolute duration is simply the difference between those two numbers, so leap days and month lengths are accounted for exactly and your device's time zone plays no part.
For the calendar difference, whole months are counted forward from the earlier date. If the earlier date's day does not exist in a later month (for example the 31st), that month is treated as ending on its last day. The days left over after the last whole month make up the "days" part.
By default the end date is not counted: 1 January to 2 January is 1 day. Turn on "Include end date" to count both dates, which gives 2 days. Inclusive counting is common for things like "the event runs from the 1st to the 3rd, so it lasts 3 days".
Examples
1 January 2024 to 5 March 2025
The absolute duration is 429 days, which is 61 weeks and 2 days. The calendar difference is 1 year, 2 months and 4 days: one year to 1 January 2025, two months to 1 March 2025, and four more days to 5 March.
Counting the end date
From 1 January 2024 to 31 January 2024 is 30 days. With "Include end date" it is 31 days, and the calendar difference becomes exactly 1 month, because both the first and last day of January are counted.
A month-end start
From 31 January 2023 to 1 March 2023 is 29 days. As a calendar difference it is 1 month and 1 day: 31 January plus one month lands on 28 February (the last day of a short month), and 1 March is one day after that.
Things to keep in mind
- Exclusive and inclusive counts differ by one day. If a result seems off by one, check the "Include end date" setting against the convention you are matching.
- The calendar difference and the day count answer different questions. Do not multiply months by 30 to compare them with the day count.
- Total hours and minutes assume 24-hour days. Real days that contain a daylight saving change are 23 or 25 hours long, which a date-only calculation cannot know.
- If the end date is before the start date, the result is shown as a positive amount and labelled as counting back.
- Dates are treated as proleptic Gregorian dates from year 1 to year 9999. Before the Gregorian calendar was adopted (from 1582, at different times in different countries) historical dates were recorded in the Julian calendar.