How the difference is worked out
Put the dates in order. Count the whole months from the earlier date, using as many as fit before the later date. Then count the remaining days. Total days is the plain count of days between them.
Months = most whole months from the earlier date that do not pass the later date; days = what is left
Adding a month to a date such as the 31st lands on the last day of a shorter month. Years = months ÷ 12 (whole), months = months mod 12. Weeks = total days ÷ 7.
How month lengths are handled
Months are not a fixed length, so the calculator never divides days by 30. It moves along the calendar, and when the start day does not exist in a later month (the 29th to 31st), it lands on that month’s last day. February has 29 days in leap years such as 2024 and 2028.
Example: years, months and days
Thu, Nov 20, 2025 to Mon, Feb 8, 2027.
- Nov 20, 2025 plus 14 months is Jan 20, 2027; 15 months would pass the end. So 14 months = 1 year, 2 months.
- Jan 20 to Feb 8, 2027 is 19 days.
- Result: 1 year, 2 months, 19 days.
- Total days: 445 = 63 weeks and 4 days.
Example: a month-end start
Sat, Jan 31, 2026 to Sun, Mar 1, 2026.
- Jan 31 plus 1 month = Feb 28 (2026 is not a leap year).
- Jan 31 plus 2 months = Mar 31, past the end, so only 1 month fits.
- Feb 28 to Mar 1 = 1 day. Result: 1 month, 1 day; 29 days in total.
Example: including the end date
Sun, Mar 1, 2026 to Tue, Mar 31, 2026, end date included.
- Including the end date counts Mar 31 as well, as if the end were Apr 1.
- Mar 1 plus 1 month = Apr 1, so the result is 1 month, 0 days, and 31 days in total.
Questions
How many days are between two dates?
Read “total days”. Jan 1 to Jan 2 is 1 day; tick “Include end date” to count both dates, which makes it 2.
Why is January 31 to March 1 “1 month, 1 day”?
January 31 plus one month is February 28 (2026). Two months would be March 31, which is past March 1. So it is 1 month, and one more day gets you from February 28 to March 1.
How are leap years counted?
From Feb 29, 2024 to Feb 28, 2025 it is 0 years 11 months 30 days, because Feb 29 plus 12 months lands on Feb 28.
What if the end date is before the start date?
The two dates are swapped and the result says so, so you always see a positive gap.
I only want weekdays between two dates.
Use the working days calculator. For hours and minutes, use the time duration calculator.