ISO Week Numbers 2027
Find ISO week numbers and Monday-to-Sunday date ranges for 2027. The current week is calculated using the UTC calendar date; each ISO year contains 52 or 53 complete weeks.
Week 43, 2026
· UTC · 52 ISO weeks in 2027
Week dates in 2027
| ISO week | Monday | Sunday |
|---|---|---|
| 2027-W01 | ||
| 2027-W02 | ||
| 2027-W03 | ||
| 2027-W04 | ||
| 2027-W05 | ||
| 2027-W06 | ||
| 2027-W07 | ||
| 2027-W08 | ||
| 2027-W09 | ||
| 2027-W10 | ||
| 2027-W11 | ||
| 2027-W12 | ||
| 2027-W13 | ||
| 2027-W14 | ||
| 2027-W15 | ||
| 2027-W16 | ||
| 2027-W17 | ||
| 2027-W18 | ||
| 2027-W19 | ||
| 2027-W20 | ||
| 2027-W21 | ||
| 2027-W22 | ||
| 2027-W23 | ||
| 2027-W24 | ||
| 2027-W25 | ||
| 2027-W26 | ||
| 2027-W27 | ||
| 2027-W28 | ||
| 2027-W29 | ||
| 2027-W30 | ||
| 2027-W31 | ||
| 2027-W32 | ||
| 2027-W33 | ||
| 2027-W34 | ||
| 2027-W35 | ||
| 2027-W36 | ||
| 2027-W37 | ||
| 2027-W38 | ||
| 2027-W39 | ||
| 2027-W40 | ||
| 2027-W41 | ||
| 2027-W42 | ||
| 2027-W43 | ||
| 2027-W44 | ||
| 2027-W45 | ||
| 2027-W46 | ||
| 2027-W47 | ||
| 2027-W48 | ||
| 2027-W49 | ||
| 2027-W50 | ||
| 2027-W51 | ||
| 2027-W52 |
Frequently asked questions
Which day starts the week?
Each calendar row starts on Monday and ends on Sunday, following ISO 8601.
How are ISO week numbers assigned?
Week 1 contains January 4, or equivalently the first Thursday of the year. Dates at either end of a year can belong to the adjacent ISO week-year.
Why do some years have 53 weeks?
An ISO year has 53 weeks when January 1 is a Thursday, or when a leap year starts on Wednesday.