Calendar Weeks Calculator

Calculate ISO and US week numbers, weeks in a year, and detailed week information.

Select Date

Year

Specific Date

Week Number

Week 5

ISO Week (Jan 26 - Feb 1)

Week Information

5

ISO Week

5

US Week

30

Day of Year

48

Weeks Left

Year 2026 Info

Total ISO Weeks53

Days in Year365

Leap YearNo

Jan 1Thursday

Dec 31Thursday

Year Progress

9.4% of the year complete