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Months Between Dates
Find how many whole calendar months and leftover days separate two dates, with decimal months for prorating and a month-by-month list you can download.
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How to use the Months Between Dates
- Pick the start date and the end date. The order doesn't matter.
- Tick “Include the end date” if both the first and last day count, as with a lease or contract that ends on the last day.
- Read the result: whole months and days, plus decimal months and total days.
- Open the month-by-month list to see every monthly period and download it as CSV.
How months between dates are counted
- Whole months: step forward one calendar month at a time from the start date (15 Jan → 15 Feb → 15 Mar). Stop before you pass the end date.
- Remaining days: count the days from the last monthly anniversary to the end date.
- Month ends: when the start day doesn't exist in a month (the 29th, 30th or 31st), use that month's last day instead.
Decimal months: calendar = months + remaining days ÷ days in the following month period, or average = total days ÷ 30.436875.
Worked examples
| From | To | Months and days | Total days | Average-month decimal |
|---|---|---|---|---|
| Jan 15, 2026 | Mar 20, 2026 | 2 months 5 days | 64 | 2.103 |
| Jan 31, 2026 | Feb 28, 2026 | 1 month 0 days | 28 | 0.920 |
| Feb 1, 2026 | Mar 1, 2026 | 1 month 0 days | 28 | 0.920 |
| Mar 3, 2026 | Mar 25, 2026 | 0 months 22 days | 22 | 0.723 |
| Sep 1, 2025 | Aug 31, 2026 (end included) | 12 months 0 days | 365 | 11.992 |
| Jun 10, 2024 | Oct 24, 2026 | 28 months 14 days | 866 | 28.452 |
Where months between dates matter
- Rent and leases: prorate a partial month using the calendar decimal, or follow the method your agreement specifies.
- Loans and subscriptions: billing usually runs on monthly anniversaries, which is exactly how whole months are counted here.
- Baby and pet ages: ages under two years are usually given in months, counted from the birth date the same way.
- Employment and probation periods: "3 months from 31 May" ends on 31 August, while "1 month from 31 May" is 30 June.
Frequently asked questions
How do you calculate the number of months between two dates?
Count how many times you can add one calendar month to the start date without passing the end date; that is the number of whole months. The days from that last monthly anniversary to the end date are the remaining days. For example, 15 January to 20 March is 2 months and 5 days.
How are months counted when the start date is the 31st?
If a month has no matching day, the anniversary falls on the last day of that month. So 31 January plus one month is 28 February (29 in a leap year), and 31 January to 28 February counts as exactly 1 month.
What is the difference between the two decimal month results?
The calendar method adds the leftover days as a fraction of the month they fall in (5 days in a 31-day month = 0.161). The average-month method divides the total days by 30.436875, the average length of a Gregorian month (365.2425 ÷ 12). Both are common; contracts usually state which to use.
Should I include the end date?
Include it when both the first and last day are covered, such as a lease from 1 September to 31 August, which is exactly 12 months only when the end date counts. Leave it off for simple date differences.
How many months are between two dates in the same month?
Zero whole months; the result is just the number of days. For example, 3 March to 25 March is 0 months and 22 days.
Why don't months between dates equal days divided by 30?
Calendar months have 28 to 31 days, so dividing by 30 drifts. From 1 February to 1 March is exactly 1 month but only 28 days (29 in a leap year).
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.
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