What Week Number Is It?
Right now it is ISO week 43 of 2026, running from Monday 2026-10-19 to Sunday 2026-10-25. 2026 has 53 ISO weeks, and today is Thursday, October 22, 2026, day 295 of the year.
This week
Today is Thursday, October 22, 2026, which sits in ISO week 43 of 2026.
Any date from any year. The ISO week year shown below can differ from the calendar year at the turn of the year.
The ISO week year can differ from the calendar year in late December or early January, when a week belongs to the neighbouring year.
Understanding week numbers
Week numbers are everywhere in business, manufacturing and project planning, especially in Europe, yet most wall calendars leave them off. A week number is a simple label for each week of the year, so colleagues can say week 32 instead of a full date range and everyone knows the same seven days are meant.
The catch is that not every country counts weeks the same way. DaysTo uses the ISO 8601 standard, the most widely adopted definition, so the numbers here match the ones used by most software, spreadsheets and European businesses.
How ISO 8601 numbers the weeks
Under ISO 8601, a week runs from Monday to Sunday, and week 1 is the week that contains the year's first Thursday. An easy way to remember it: week 1 always contains January 4, and it always contains the first Thursday of the year. This rule ensures each week belongs to exactly one year and avoids the ambiguity of counting partial weeks.
52 or 53 weeks
Because 365 days do not divide evenly into seven, most years span 52 ISO weeks with a day or two left over, and occasionally a year covers 53 weeks. A year has 53 weeks when January 1 falls on a Thursday, or when a leap year begins on a Wednesday. The tool computes the exact total for whatever year you look up.
Week years and the December edge
Near the turn of the year, a single calendar week can straddle two years. ISO assigns that week to whichever year holds most of it, which is why the last days of December sometimes belong to week 1 of the following year, and the first days of January can belong to week 52 or 53 of the previous one. The ISO week year field makes that ownership explicit.
Which years have 53 weeks
This is the part people actually look up, because a 53-week year means an extra reporting period in payroll and retail planning. The table below is computed from the ISO rule, not copied from anywhere.
| Year | ISO weeks | Week 1 starts | Full calendar |
|---|---|---|---|
| 2020 | 53 (53-week year) | 2019-12-30 | Week numbers 2020 |
| 2021 | 52 | 2021-01-04 | Week numbers 2021 |
| 2022 | 52 | 2022-01-03 | Week numbers 2022 |
| 2023 | 52 | 2023-01-02 | Week numbers 2023 |
| 2024 | 52 | 2024-01-01 | Week numbers 2024 |
| 2025 | 52 | 2024-12-30 | Week numbers 2025 |
| 2026 | 53 (53-week year) | 2025-12-29 | Week numbers 2026 |
| 2027 | 52 | 2027-01-04 | Week numbers 2027 |
| 2028 | 52 | 2028-01-03 | Week numbers 2028 |
| 2029 | 52 | 2029-01-01 | Week numbers 2029 |
| 2030 | 52 | 2029-12-31 | Week numbers 2030 |
| 2031 | 52 | 2030-12-30 | Week numbers 2031 |
| 2032 | 53 (53-week year) | 2031-12-29 | Week numbers 2032 |
| 2033 | 52 | 2033-01-03 | Week numbers 2033 |
| 2034 | 52 | 2034-01-02 | Week numbers 2034 |
| 2035 | 52 | 2035-01-01 | Week numbers 2035 |
A worked example of the December edge
Take 31 December 2029. It is a Monday, so it opens a new week, and that week contains the first Thursday of 2030. It therefore belongs to ISO week 1 of 2030, even though the calendar still says 2029. Run the same test on 1 January 2027: it is a Friday, so its week contains the last Thursday of 2026, and it belongs to ISO week 53 of 2026. Both answers look wrong at first glance and both follow directly from the same one-line rule.
Frequently asked questions
What week number is it right now?
The tool shows the current ISO 8601 week number at the top of the page, based on your device's local date. ISO weeks start on Monday, and week 1 is the week that contains the first Thursday of the year.
How is the ISO week number defined?
Under ISO 8601, weeks begin on Monday and week 1 is the week containing the year's first Thursday, which is the same as the week containing January 4. This rule keeps week numbering consistent across countries and software.
How many weeks are in a year?
Most years have 52 ISO weeks, but some have 53. A year has 53 weeks when it starts on a Thursday, or when it is a leap year that starts on a Wednesday. The tool reports the exact count for the year you enter.
Why does the week year sometimes differ from the calendar year?
Days at the very start or end of a year can belong to a week that mostly falls in the neighbouring year. For example, December 31 can be part of week 1 of the next year. The ISO week year labels which year owns that week.
Do week numbers reset each year?
Yes. Week numbering restarts at week 1 for each ISO week year. Because of the first-Thursday rule, the first ISO week can begin in late December of the previous calendar year.
Need a whole year at once? The full ISO week calendar for 2026 lists every week with its Monday and Sunday, and the same data is published as free JSON on the data page. Counting days rather than weeks? Use the date calculator.
Computed from the ISO 8601 rule. Last updated 2026-08-05.
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