Dates & Time

Excel formula for First day of the week for a date

Snap any date back to the Monday (or Sunday) that starts its week.

Copy this formula

=A2-WEEKDAY(A2, 2)+1

How the formula works

WEEKDAY(A2, 2) numbers Monday as 1…Sunday as 7; subtracting it and adding 1 lands on that week's Monday. Use type 1 (Sunday = 1) and drop the +1 for a Sunday week start.

Examples

=A2-WEEKDAY(A2, 2)+1→2026-06-22

Monday of the week containing the date.

=DATE(2026,10,7)-WEEKDAY(DATE(2026,10,7), 2)+1→2026-10-05

Wednesday 7 October 2026 belongs to the week starting Monday 5 October.

=DATE(2026,10,7)-WEEKDAY(DATE(2026,10,7))+1→2026-10-04

With the default numbering, the week starts on Sunday.

FAQ

How do I get the end of the week?

Add 6 to the week-start: =A2-WEEKDAY(A2, 2)+7 lands on Sunday.

How do I get the Monday of the following week?

Add 7 to the week start: =A2-WEEKDAY(A2, 2)+8.

How do I get the ISO week number?

Use =ISOWEEKNUM(A2). ISO weeks start on Monday, and week 1 is the week containing the first Thursday of the year.

How do I group dates by week?

Add a helper column with the week-start formula, then use it as the row field in a PivotTable or as the criterion in SUMIFS.

Related formulas

Get the week number from a date Get the day of the week

Functions used

WEEKDAY

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