Convert between days, months and years in both directions, and add months to a date.
Adding months to 31 January lands on the last day of the target month where the day does not exist.
months
How to use this tool
Type the number, for example 180.
Days to months is the default; any pair of days, weeks, months and years works.
The years / months / days breakdown helps with durations like ages and contracts.
Under Advanced options, pick a start date and months to add for an exact calendar result.
Formula & worked example
180 days ÷ 30.4375 = 5.91 months (about 6 calendar months). 50 months ÷ 12 = 4.17 years, or 4 years and 2 months.
Limitations — read this before you rely on it
Calendar months are 28–31 days, so 'months' from days is always an approximation unless you use real dates. For exact calendar maths, use the add-months-to-a-date option.
Frequently asked questions
About 5.91 average months, or roughly 6 calendar months depending on which months they span.
50 ÷ 12 = 4.17 years, i.e. 4 years and 2 months.
Calendar months have 28–31 days; the average month is 30.4375 days (365.25 ÷ 12).
Use the Advanced date option: adding 1 month to 31 January gives 28 February (or 29 in a leap year).
Weeks are exact (7 days). Months are not, which is why this calculator states its average-month basis.