Plan with consistent week numbers
Work Week Calendar and Week Number Planner
This calendar combines a live current-week result with precise week lookups and a complete year view. It is useful for construction schedules, engineering reports, project controls, timesheets, delivery plans and any workflow organized by numbered weeks.
1. Find the week
See the current week immediately or look up a date, week number and year.
2. Choose a convention
Compare ISO, Sunday-start, Monday-start and custom week definitions.
3. Download the calendar
Export the displayed year as an A4 or US Letter PDF.
What Is a Work Week?
A work week is a repeating seven-day period used to organize working time, reporting and schedules. The numbered calendar week and the days an organization treats as working days are separate settings: a week may run Monday–Sunday while actual working days are Monday–Friday.
How Work Week Numbers Are Calculated
A week number is counted from a system-specific Week 1. The selected first weekday establishes each seven-day boundary, while the first-week rule determines whether a partial week around New Year belongs to the old or new week-year.
ISO 8601 Week Numbering
ISO 8601 weeks start on Monday. Week 1 is the week containing at least four days of the new year, equivalently the week containing 4 January or the first Thursday. An ISO week-year can contain 52 or 53 weeks.
US Week Numbering
There is no single week-numbering convention used in every US context. This tool provides Sunday-start and Monday-start variants where the week containing 1 January is Week 1, and clearly labels the convention used.
Why Week Numbers Differ Between Systems
Changing the first weekday or Week 1 rule moves calendar boundaries. The same date can therefore have different week numbers in different systems, especially near the beginning and end of a year.
How to Find the Current Work Week
Open the page and the current local date is converted into the selected week system. The top panel shows the week number, its week-year, start and end. Use Previous, Next or Current Week to move without re-entering dates.
How to Find Dates for a Week Number
Enter the relevant week-year and week number in the lookup panel. A week-year matters because ISO Week 1 may begin in December and the last ISO week may finish in January.
Work Week Calendar for Construction and Project Management
Numbered weeks offer a compact reference for look-ahead plans, progress reports, procurement dates and site coordination. Always state the convention—such as ISO 8601—when schedules cross organizations or countries.
Downloading a Week Calendar
Use Download PDF at the top of the calendar, choose A4 or US Letter and select the orientation. The exported calendar includes the currently displayed year, all 12 months, week-number columns, the selected convention and current-week context.
Work Week Calendar FAQ
What work week are we in?
The answer depends on the week-numbering system. This page defaults to ISO 8601 and calculates the current week from your device's local calendar date. The highlighted result includes the week number, week-year and exact date range.
What is the current ISO week number?
The large result at the top shows the current ISO week automatically. ISO weeks begin on Monday and end on Sunday.
What dates are in a specific week number?
Enter a week-year and week number in the Find a Week panel. The calendar returns the exact start and end dates under the selected week system.
Why can early January belong to the previous week-year?
Under ISO 8601, Week 1 is the week containing 4 January and at least four days of the new year. Therefore, 1–3 January can belong to the final ISO week of the previous week-year.
When does a year have Week 53?
An ISO week-year has 53 weeks when its calendar arrangement creates an extra complete ISO week. The calendar detects this mathematically for each selected year instead of assuming every year has 52 weeks.
What is ISO 8601 week numbering?
ISO 8601 is the international standard commonly used for business schedules. Weeks run Monday through Sunday, and Week 1 contains the year's first Thursday.
How do US and ISO week numbers differ?
ISO weeks begin Monday and use the four-day rule. A common US convention begins Sunday and treats the week containing 1 January as Week 1. Different software and organizations may use other US conventions.
Can I start the week on Sunday or Monday?
Yes. Choose ISO, US Sunday Start, US Monday Start or a custom first weekday. The week number, date ranges and calendar update together.
Can I define my own working days?
Yes. Working days are independent from week numbering. Use Monday–Friday, Sunday–Thursday, Monday–Saturday or a custom selection to see the working-day range for the selected week.
Can I download a week number calendar?
Yes. Download the currently displayed year as a PDF in A4 or US Letter, using portrait or landscape orientation. You can then print the downloaded PDF if needed.
Does the calendar use my local date?
Yes. The current-week result uses the local calendar date supplied by your browser. It does not require a network time or location service.
Can I share a selected work week?
Yes. The selected year, week and system are reflected in the page URL, so you can copy the address. Custom convention details are not currently encoded in the URL.
Is the Work Week Calendar free?
Yes. The calendar, week lookups and PDF export are free and require no signup.
Related Date & Time Tools
Calendar results are calculated locally in your browser. Confirm the week convention used by your employer, client or reporting system before relying on a week number for formal planning.