Month difference calculator
Count the month gap between two dates as calendar months only, ignoring the day of month. Example: 2025-01-31 to 2025-03-01 gives 2 months.
What to know
This page returns the absolute number of calendar months between two dates, using months = |(year2 - year1) x 12 + month2 - month1|. The day of the month is ignored completely, and the order of the two dates does not matter.
That makes it quick but blunt. 2025-01-31 to 2025-03-01 is 2 months even though only 29 days separate them, while 2025-01-01 to 2025-12-31 is 11 months although it spans almost a full year. Both ends are treated as if they sat on the same day.
Use it when you plan in month slots: billing cycles, subscription periods, lease terms, semester counts or installment plans. The month index of 2025-03 minus 2025-01 is what you want in those cases, not the number of days divided by 30.
If you need to know whether a full month has actually elapsed, compare the day of month yourself or use the date-difference page for the exact days. For ages in completed years, the age page applies the birthday rule instead.
Subscriptions are the classic case: a plan started on 2025-01-31 and reviewed on 2025-06-01 reads 5 months, which matches a billing calendar that renews on the same day of each month, even though the elapsed days are 121.
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How to use Month difference calculator
- Type 2025-01-31 as the Start date.
- Enter End date 2025-03-01.
- Read the Result line, which shows 2 months.
- Swap the dates and the same 2 months appears, because the value is absolute.
Quick answers
Why is January 31 to March 1 two months?
Only the year and month are compared: March is month 3 and January is month 1, so the gap is 2. The 31st and the 1st are ignored.
How many months are between 2024-12-15 and 2026-02-01?
14 months: (2026 - 2024) x 12 + 2 - 12 = 14. The day numbers play no role.
Can the result be negative?
No. The page always reports the absolute value, so an earlier End date gives the same number as a later one.
Is this the same as days divided by 30?
No. The count follows calendar months, so a 31-day span from January into February can still read as 1 month or 0 depending on the month labels.