How many months are between two dates? Enter a start and an end date and the month calculator counts the whole calendar months and the days left over, shows the result in years, months and days, and gives the decimal months for quick estimates.
9 months and 12 days
- Years, months and days
- 9 months, 12 days
- Whole months
- 9
- Months (average length)
- 9.36
- Total days
- 285
- In weeks
- 40 weeks and 5 days
From February 1, 2026 to November 13, 2026 is 9 months and 12 days (285 days, about 9.36 months on average month length).
How it’s calculated
Whole months are counted on the calendar: from the 15th to the 15th is one month, whatever the month’s length. When the start day does not exist in a later month, the month ends on that month’s last day (January 31 + 1 month = February 28, or 29 in a leap year). The days after the last whole month are added as days.
Months (average length) = days ÷ 30.436875, the average Gregorian month (365.2425 ÷ 12). Use it for rough estimates only: contracts, leases and notice periods count calendar months.
Worked example with your numbers
- Count whole calendar months from February 1, 2026: 9 months later is November 1, 2026.
- One more month would be December 1, 2026, which is after November 13, 2026, so the whole months stop at 9.
- Days left: November 13, 2026 − November 1, 2026 = 12 days.
| Dates | Months and days | Days |
|---|---|---|
| January 31, 2027 → February 28, 2027 | 1 month | 28 |
| January 31, 2027 → March 1, 2027 | 1 month and 1 day | 29 |
| August 15, 2026 → February 14, 2027 | 5 months and 30 days | 183 |
| February 29, 2024 → February 28, 2027 | 36 months | 1,095 |
| Month | Days | Weeks | Days since January 1 (end of month) |
|---|---|---|---|
| January | 31 | 4 weeks and 3 days | 31 |
| February | 28 | 4 weeks | 59 |
| March | 31 | 4 weeks and 3 days | 90 |
| April | 30 | 4 weeks and 2 days | 120 |
| May | 31 | 4 weeks and 3 days | 151 |
| June | 30 | 4 weeks and 2 days | 181 |
| July | 31 | 4 weeks and 3 days | 212 |
| August | 31 | 4 weeks and 3 days | 243 |
| September | 30 | 4 weeks and 2 days | 273 |
| October | 31 | 4 weeks and 3 days | 304 |
| November | 30 | 4 weeks and 2 days | 334 |
| December | 31 | 4 weeks and 3 days | 365 |
Calendar months vs. average months
Calendar months follow the dates: March 15 to April 15 is one month even though March has 31 days. Average months divide days by 30.44, so 180 days ≈ 5.91 months. Leases, notice periods, probation periods and warranties usually count calendar months; budgets and estimates often use the average.
More date calculators
To find the date a number of months from a date, use the add or subtract days calculator (it adds months and years too). For exact days, use days between dates; for weeks, the weeks calculator.
Frequently asked questions
How do you calculate the months between two dates?
Count how many times you can add one calendar month to the start date without passing the end date, then count the remaining days. The calculator does it for any two dates.
How many months is it from January 31 to February 28?
One month: when a month has no 31st, a month after January 31 ends on that month’s last day.
How many months is 180 days?
About 5.91 months on the average month length (180 ÷ 30.44). Six calendar months are 181 to 184 days.
How many months old is a baby born on a date?
Enter the birth date as the start and today as the end; the whole months are the baby’s age in months. The age calculator also shows it.