Week Number Calculator
Find out what week number any date falls on, plus the week start, week end, and weeks remaining in the year.
Results
Week Number
Week 18
Week Start
Monday, April 27, 2026
Week End
Sunday, May 3, 2026
Days Left in Week
4 days
Weeks Left in Year
35 weeks
Frequently Asked Questions
What is a week number?
A week number is the sequential number of a week within a year. Week 1 is the first week of the year, and most years have 52 weeks. Week numbers are commonly used in project management, payroll cycles, academic calendars, and scheduling.
What week number is it today?
Load this page and today's date is automatically calculated. The current week number is shown instantly with the week start and end dates.
Does the week start on Monday or Sunday?
This tool uses ISO 8601 week numbering, which defines Monday as the first day of the week. This is the international standard used across Europe and in most professional and academic contexts.
What is ISO week numbering?
ISO 8601 is an international standard for dates and times. Under this standard, Week 1 is defined as the week containing the first Thursday of the year. This means January 1st can sometimes fall in the last week of the previous year.
How many weeks are in a year?
Most years have 52 weeks. Some years have 53 ISO weeks — these are called long years. Whether a year has 53 weeks depends on what day of the week January 1st falls on.