Months Between Dates Calculator
Enter a start date and an end date. The end date starts as today and must not be before the start.
Updated
Report a problem
Formula
full months = 12 × whole years + whole months between the two dates, counted on the start date's day of the month (clamped to the last day of shorter months).
decimal months = total days ÷ 30.4375
Worked example
15 January 2024 to 20 April 2024: 15 January to 15 April is 3 full months (91 days), plus 5 extra days, so 3 months and 5 days. The total is 96 days, and 96 ÷ 30.4375 = 3.15 months.
Frequently asked questions
How are the months between two dates counted?
Whole months are counted from the start date on the same day of each month, and the remaining days are shown separately. From 15 January to 20 April 2024 that is 3 months and 5 days.
What happens when the start date is the 31st?
A month that is too short ends on its last day. From 31 January to 28 February 2023 counts as 1 full month.
How is the decimal number of months worked out?
The total days are divided by the average month length of 30.4375 days. 96 days gives 96 ÷ 30.4375 = 3.15 months.
Why do I get a date error?
Both dates must exist, such as not 30 February, and the end date cannot be earlier than the start date.