Date & Time • Precision Calculator

Week Number Calculator

Determine the official ISO-8601 calendar week number for any specific date, or look up start and end dates for any week of the year. Essential for corporate fiscal planning, manufacturing, and logistics.

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ISO-8601 Standard Rule

According to ISO-8601, weeks start on Monday. Week 1 is the first week with a majority of 4 or more days in the new year (i.e. containing the first Thursday of January).

Week Details

ISO Week Number
Week 45
Nov 2, 2026 — Nov 8, 2026
Week Starts (Monday)
Monday, November 2, 2026
Week Ends (Sunday)
Sunday, November 8, 2026

All Weeks for Year 2026

Week #From (Mon)To (Sun)
Week 1 2025-12-292026-01-04
Week 2 2026-01-052026-01-11
Week 3 2026-01-122026-01-18
Week 4 2026-01-192026-01-25
Week 5 2026-01-262026-02-01
Week 6 2026-02-022026-02-08
Week 7 2026-02-092026-02-15
Week 8 2026-02-162026-02-22
Week 9 2026-02-232026-03-01
Week 10 2026-03-022026-03-08
Week 11 2026-03-092026-03-15
Week 12 2026-03-162026-03-22
Week 13 2026-03-232026-03-29
Week 14 2026-03-302026-04-05
Week 15 2026-04-062026-04-12
Week 16 2026-04-132026-04-19
Week 17 2026-04-202026-04-26
Week 18 2026-04-272026-05-03
Week 19 2026-05-042026-05-10
Week 20 2026-05-112026-05-17
Week 21 2026-05-182026-05-24
Week 22 2026-05-252026-05-31
Week 23 2026-06-012026-06-07
Week 24 2026-06-082026-06-14
Week 25 2026-06-152026-06-21
Week 26 2026-06-222026-06-28
Week 27 2026-06-292026-07-05
Week 28 2026-07-062026-07-12
Week 29 2026-07-132026-07-19
Week 30 2026-07-202026-07-26
Week 31 2026-07-272026-08-02
Week 32 2026-08-032026-08-09
Week 33 2026-08-102026-08-16
Week 34 2026-08-172026-08-23
Week 35 2026-08-242026-08-30
Week 36 2026-08-312026-09-06
Week 37 2026-09-072026-09-13
Week 38 2026-09-142026-09-20
Week 39 2026-09-212026-09-27
Week 40 2026-09-282026-10-04
Week 41 2026-10-052026-10-11
Week 42 2026-10-122026-10-18
Week 43 2026-10-192026-10-25
Week 44 2026-10-262026-11-01
Week 45 Current2026-11-022026-11-08
Week 46 2026-11-092026-11-15
Week 47 2026-11-162026-11-22
Week 48 2026-11-232026-11-29
Week 49 2026-11-302026-12-06
Week 50 2026-12-072026-12-13
Week 51 2026-12-142026-12-20
Week 52 2026-12-212026-12-27
Week 53 2026-12-282027-01-03

How to Use Week Number Calculator Online

  1. Pick any date: Select a date from the calendar or choose "Today".
  2. View ISO-8601 week: Instantly view the standard calendar week number (Week 1 through Week 53).
  3. Check week date range: See the exact Monday-to-Sunday date span for that week.

ClickBasic tools run 100% securely with zero installation, no registration, and no limits.

Key Features of ClickBasic Week Number Calculator

ISO-8601 International Standard: Complies with global business calendar standards where Monday is the first day of the week.
Week Date Range Display: Shows the exact start date (Monday) and end date (Sunday) for any week number.
Year Progress Percentage: Visual gauge showing how much of the current year has elapsed.
Free & Fast: Instant answers for project management and business sprint planning.

Frequently Asked Questions

ISO-8601 defines week 1 of a year as the week that contains the first Thursday of January, or the week with January 4th. Weeks run from Monday to Sunday.

Most years have 52 weeks (364 days), while leap years or years starting on Thursday can have 53 weeks.

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