Exceljet

Quick, clean, and to the point

Data validation allow weekday only

Excel formula: Data validation allow weekday only
Generic formula 
=WEEKDAY(A1,2)<6
Explanation 

Note: Excel has several built-in data validation rules for dates. This page explains how to create a your own validation rule based on a custom formula if you need more control or flexibility.

To allow a user to enter only dates that are weekdays (i.e. Monday, Tuesday, Wednesday, etc.) you can use data validation with a custom formula based on the WEEKDAY function.

In the example shown, the data validation applied to C5:C7 is:

=WEEKDAY(C5,2)<6

How this formula works

Data validation rules are triggered when a user adds or changes a cell value.

This custom validation formula uses the WEEKDAY function to get a numeric value, 1-7, corresponding to to a week beginning Monday (1) and ending Sunday (7). To get a number for a Monday-based week, the return_type argument for WEEKDAY is provided as 2.

The WEEKDAY result is then compared to 6. Any value less than 6 is a weekday, so the expression returns TRUE and validation succeeds. If the weekday number is not less than 6, validation fails because the date is a Saturday or Sunday.

Date is weekend

To allow only dates that occur on a weekend (Saturday or Sunday), you can use a similar formula:

=WEEKDAY(C5,2)>5

Note:  Cell references in data validation formulas are relative to the upper left cell in the range selected when the validation rule is defined, in this case C5.

Author 
Dave Bruns

Excel Formula Training

Formulas are the key to getting things done in Excel. In this accelerated training, you'll learn how to use formulas to manipulate text, work with dates and times, lookup values with VLOOKUP and INDEX & MATCH, count and sum with criteria, dynamically rank values, and create dynamic ranges. You'll also learn how to troubleshoot, trace errors, and fix problems. Instant access. See details here.