How to say "a year has 12 months"?

Question

一年は十二ヶ月があります. I'm trying to say "a year has 12 months" or "there are 12 months in a year." Is the above sentence correct?

Answer 1

1年は12ヶ月あります

がんばって！

Answer 2

A calendar year presently measures twelve-month's-time equal in length to that of a year in the calendar conventionally in use. However, previous century calendars in different world countries were measured in different increments of months, etc. (Gregorian, Julian, Augustan...). Therefore, I guess you might say that 'a calendar year includes twelve months. A calendar is an orderly system that measures conventional time in terms of 12-month-increments.