Dates & time

Day of the week

Find the weekday, day of the year and ISO week number.

Day of the week
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A clear answer. Here’s how.

Uses the Gregorian calendar. ISO weeks start on Monday; week 1 contains the year’s first Thursday. The ISO week year can differ from the calendar year near January.

See a worked example

Worked example

A fixed demonstration, separate from the values you enter above.

Date
2026-01-01

Example result

Day
Thursday
Day of year
1
ISO week
2026-W01

Keep going.

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