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Calendar Week Calculator
Find ISO week numbers, quarters, and day-of-year
Week Number
13
Tuesday
Year Progress25%
Week 13 of 53 weeks in 2026
2026 Week Calendar
| Week | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
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| W53 |
About ISO Week Numbers
ISO 8601 defines week 1 as the week containing the first Thursday of the year. Weeks start on Monday. A year can have 52 or 53 weeks. The format is YYYY-Www (e.g., 2026-W08).