Convert between Gregorian dates and ISO week dates (ISO 8601)
ISO week: β
Weekday: β
Date: β
ISO weeks start on Monday. ISO week 01 is the week with the year's first Thursday (or Jan 4).
Used by project managers, developers, accountants, and planners worldwide, this ISO week counter helps calculate accurate ISO week numbers based on international standards.
The ISO week counter is a free online tool that helps you find the ISO week number for any date instantly. It follows the ISO-8601 international date standard used in business, finance, project management, and software systems.
Whether you need the ISO week number now, an ISO week number calendar, or an ISO week counter from date, this tool delivers fast and reliable results.
An ISO week number is part of the ISO-8601 standard, where each year is divided into numbered weeks. ISO weeks start on Monday and end on Sunday.
The ISO week number now feature shows the current week according to the ISO calendar, helping teams track schedules, deadlines, and weekly planning accurately.
The ISO week calculator allows you to select any date and instantly calculate its corresponding ISO week number.
With the ISO week counter by date, you can find the exact ISO week for any past, present, or future date. This is especially useful for reports, payroll, sprint planning, and compliance documentation.
An ISO week number calendar displays all ISO weeks for a given year, making it easy to see weekly breakdowns at a glance.
This tool also works as an ISO week counter calendar, helping you track week progression throughout the year.
The ISO week number 2025 view helps you understand how weeks are structured for the year 2025 under the ISO-8601 standard. This is useful for long-term planning and yearly schedules.
These ISO week counters ensure consistent week calculations across regions and systems.
Quickly calculate ISO week numbers using the ISO week counter calculator.
Check ISO Week Number Now