Week numbers 2028: calendar weeks with dates

Computed from the ISO 8601 week rules. Last updated 23 October 2026.

Week numbers 2028: the 52 ISO calendar weeks of 2028, each with its Monday and Sunday dates. 2028 is a leap year that starts on a Saturday, so 1 and 2 January still belong to week 52 of 2027, and the year ends exactly on the Sunday of week 52.

With JavaScript on, this line names the week that contains today and marks it in the table.

Every week of 2028

ISO weeks run from Monday to Sunday. Week 1 of 2028 starts on Monday 3 January 2028 and week 52 ends on Sunday 31 December 2028. Dates outside 2028 show their year.

Need the week for one date, or a date outside 2028? The week number calculator gives the ISO week, the US week and the day of the year for any date, and the dates of any week.

Why 2028 has 52 weeks

Being a leap year does not give 2028 a 53rd ISO week. That needs a year starting on a Thursday, or a leap year starting on a Wednesday, and 1 January 2028 is a Saturday. The Thursday of the week holding Saturday 1 and Sunday 2 January is 30 December 2027, so those two days are the end of 2027's week 52, and week 1 of 2028 opens on Monday 3 January 2028. The extra day, Tuesday 29 February, simply lengthens February: it falls in week 9, which runs from 28 February to 5 March.

The end of the year is unusually tidy. 31 December 2028 is a Sunday, so week 52 (25 December to 31 December 2028) closes on the last day of the calendar year, and 2029's week 1 starts on Monday 1 January 2029. Nothing at the end of 2028 spills into the next week-year. The next year with 53 ISO weeks is 2032.

ISO weeks and US (Sunday start) weeks in 2028

This is where 2028 is rare. Under the Sunday-start rule that US wall calendars use, and that Excel's WEEKNUM returns with its default setting, week 1 is the week containing 1 January. In 2028 that week is Sunday 26 December 2027 to Saturday 1 January 2028, so week 1 holds just one day of the new year, and Sunday 2 January is already week 2. Because a leap year has 366 days, the count then runs to Sunday 31 December, which starts a week of its own: week 54, one day long. A leap year that begins on a Saturday is the only kind that reaches week 54; the last one was 2000 and the next after 2028 is 2056.

So a spreadsheet using WEEKNUM numbers 2028 from 1 to 54, while ISOWEEKNUM, and the table above, number it from 1 to 52. Through most of the year the Sunday-start number runs one ahead of the ISO number, and two ahead on Sundays: Independence Day, Tuesday 4 July 2028, is ISO week 27 but week 28 on a Sunday-start calendar. A weekly report keyed on week numbers needs to say which system it uses, and the week number calculator shows both for any date.

Weeks that cross a month boundary

10 of the 52 weeks in 2028 run from one month into the next: numbers 5, 9, 13, 22, 26, 31, 35, 39, 44, 48. Neither end of the year is among them, because week 1 starts on 3 January and week 52 ends on 31 December. When a team reports by month as well as by week, it helps to decide once whether a split week counts in the month of its Monday, its Thursday or most of its days, and use that rule all year.

See also week numbers for 2026, 2027 and 2028, or go straight to week numbers 2026 or week numbers 2027. For deadlines in working days, the business days calculator skips weekends and your own holidays.