Weeks Calculator for ISO dates and planning ranges
Use focused calculators and ISO week references for deadlines, reporting periods, payroll schedules, project timelines, and calendar planning.
Calculate weeks in seconds
Choose the right tool for week numbers, dates, and deadlines
Weeks Between Dates
Compare two dates and see the exact week and day difference.
Calculate nowDate to Week Number
Find the ISO week number and Monday–Sunday range for any date.
Convert nowBusiness Days Calculator
Count workdays between dates while excluding weekends.
Calculate nowDeadline Calculator
Add or subtract days, weeks, or business days from a date.
Calculate nowNeed the full ISO week calendar?
Open a clean Monday-to-Sunday ISO calendar for 2026, with week totals, exact ranges, and the current week highlighted automatically.
Open Full Week Calendar →
Useful calculators for recurring schedules
Learn how week numbers work
Find the current ISO week number and see how week numbers help with planning.
See today’s ISO week number and how it applies to schedules, reports, and planning.
A clear explanation of ISO weeks, week-years, and the rule that defines week 1.
Quick answers
What is an ISO week?
An ISO week runs from Monday to Sunday. Week 1 is the first week that contains at least four days of January.
How do I calculate weeks between two dates?
Select a start and end date. The calculator shows full weeks, total days, and any remaining days.
How many weeks are in a year?
Most years have 52 ISO weeks. Some have 53, depending on how the calendar aligns at the start and end of the year.
Plan with ISO weeks, exact date ranges, and simple calculators
Use WeeksCalculatorPro when you need a clear week number, a Monday-to-Sunday date range, or a quick count between two dates. Week numbers are useful for planning projects, business reports, school terms, payroll cycles, recurring schedules, and personal deadlines.
ISO week calendar
Browse every ISO week in the selected year. Each calendar row starts with the week number, followed by Monday through Sunday.
Open the week calendar →More planning tools
Calculate deadlines, build week-based project timelines, and estimate weekly or biweekly payroll periods.
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