May 18–24, 2026
MonTueWedThuFriSatSun
Week 1 contains the first Thursday of the year.ISO guide →Date → week number
May 18, 2026: What week number?
Monday, May 18, 2026ISO Week 212026-W21
ISO Week 21 runs from May 18, 2026 to May 24, 2026.
ISO vs US-style week numbers
The same date can have different week numbers
ISO weeks start on Monday. The simplified US-style system starts on Sunday and counts the week containing January 1 as Week 1.
May 17–23, 2026
SunMonTueWedThuFriSat
Week 1 contains January 1.US-style guide →ISO weekWeek 21
US-style weekWeek 21
WeekdayMonday
QuarterQ2
Day of year138 / 365
ISO weekday1 / 7
May 2026
Date context
Monday, May 18, 2026 is day 138 of 2026 and belongs to ISO Week 21.
The entire ISO Week 21 falls within May.
Distance from today
How long ago was May 18, 2026?
Days141
Full weeks20
Remaining days1
May 18, 2026 is 141 days before today, equal to 20 full weeks and 1 days.