An average year is exactly 52.1775 weeks long; months (1/12 year) average at exactly 4.348125 weeks. An ISO week-numbering year (also called ISO year informally) has 52 or 53 full weeks. That is 364 or 371 days instead of the usual 365 or 366 days.How many weeks are in a calendar?
There are 53 weeks in 2020. All weeks are starting on Monday and ending on Sunday. Please note that there are multiple systems for week numbering, this is the ISO week date standard (ISO-8601), other systems use weeks starting on Sunday (US) or Saturday (Islamic).