How many weeks in a year? A detailed Explanation

How many weeks in a year

How many weeks in a year are actually? In this article, you will know the exact number of weeks in a year and what factors influence this.

Before knowing how many weeks in a year, you must know what a year is. 

What is a year?

One year is the time that the Earth takes to make a complete revolution around the sun. There are 365 days in a year, which is divided into 12 months. Each year begins on January 1 and ends on December 31, which makes a total of 12 months in our calendar. Every four years, however, the year lasts 366 days. Continue reading this if you want to know how many weeks in a year and how to calculate them and find out what explains this change!

How many weeks are there in a year or in 365 days?

Each week has 7 days : Monday, Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday. However, the number of weeks in a year may not be exactly 52. ​​This number may vary depending on the day on which the year begins. If the year ends on a Thursday or begins on a Tuesday, for example, these two weeks will not be fully counted. A week is complete only when it begins on a Monday and ends on a Sunday .

The leap years have 366 days instead of 365 and this happens when, in February there are 29 days, not 28 days. Leap year comes every 4 years.

If you are wondering how many weeks in a year, you should know that the answer is 52 weeks. To calculate it manually, nothing could be simpler: divide 365, or the number of days in a year, by 7, the number of days in a week.

356/7 = 52.1

52 weeks and 1 day extra. 

So you got the answer to your question: how many weeks in a year and it’s 52 weeks. Some times a year has 53 weeks and this will also be explained in the section: Why does our calendar sometimes have 53 weeks in a year?

Calculation of weeks in a year

A year is about 52 weeks. Or sometimes 53 weeks.

How many weeks in a common year?

Let’s calculate and know how many weeks are there in a year.

A common calendar year has 365 days:

1 common year = 365 days = (365 days) / (7 days / week) = 52.143 weeks = 52 weeks + 1 day

How many weeks in a leap year?

 A leap calendar year occurs every 4 years, except for years divisible by 100 and not divisible by 400.

A calendar leap year has 366 days, while February has 29 days:

1 leap year = 366 days = (366 days) / (7 days / week) = 52.286 weeks = 52 weeks + 2 days

Graph of weeks in a year

Leap year
Weeks ina year
2013non52 weeks + 1 day
2014non52 weeks + 1 day
2015non52 weeks + 1 day
2016Yes52 weeks + 2 days
2017non52 weeks + 1 day
2018non52 weeks + 1 day
2019non52 weeks + 1 day
2020Yes52 weeks + 2 days
2021non52 weeks + 1 day
2022non52 weeks + 1 day
2023non52 weeks + 1 day
2024Yes52 weeks + 2 days
2025non52 weeks + 1 day
2026non52 weeks + 1 day

How many weeks are there in a year?

Number of weeks in 2022, 2023, 2024, 2025, 2026

From a purely mathematical point of view there are indeed 52 complete weeks in a year . Indeed if we divide 365 (number of days in a regular year) by 7 (number of days in a week) we obtain 52.1428, i.e. 52 weeks and 1 day.

It is the same when the year is a leap year (366 days) because by doing the same calculation we obtain 52.2857 or 52 weeks and 2 days. So why do our calendars sometimes mention a 53rd week?

Why does our calendar sometimes have 53 weeks?

According to the ISO-8601 standard used by companies, a week begins on Monday and ends on Sunday, and a week depends on a year when it places a majority of its seven days in the year in question, or at least four. Therefore, week 1 is the week of the first Thursday of the year.

To know if the annual calendar has 52 or 53 weeks, you must know the day of January 1. If January 1 falls on a Thursday (regular year and leap year) or Wednesday (leap year only) the ISO year will have 53 weeks. In all other cases the ISO year will count 52 weeks.

How to know if a year has 52 or 53 weeks?

Day1 JanuaryRegular year365 daysLeap year366 days
On Saturday5252

As shown in the table above, regular years, like leap years, sometimes have 53 weeks. In a 400-year calendar cycle, 71 ISO years are 53 weeks and 329 are 52 weeks long. For more explanations on this subject, we advise you to consult the wikipedia article on ISO numbering of weeks.

Summary table of the number of weeks per year

for the coming years

The table below covers the period from 2022 (current year) to 2040. It will let you know if the year mentioned has 52 or 53 weeks.

YearNumber ofweeksDate ofJanuary 1
202252Saturday January 1
202352Sunday January 1
202452Monday January 1
202552Wednesday January 1
202653Thursday January 1
202752Friday January 1
202852Saturday January 1
202952Monday January 1
203052Tuesday January 1
203152Wednesday January 1
203253Thursday January 1
203352Saturday January 1
203452Sunday January 1
203552Monday January 1
203652Tuesday January 1
203753Thursday January 1
203852Friday January 1
203952Saturday January 1
204052Sunday January 1

As shown in the table above our annual calendar counts most of the time 52 weeks except every 5 or 6 years or 53 weeks ago.


Most of the time, the number of weeks in a year is 52. However, when January 1 of the year is a Thursday or Wednesday in a leap year, then the year has 53 weeks.

Got the answer to your question: how many weeks in a year? If yes, comment your confusion in the comment box. 

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