Count of weekdays

A1 Start date

A2 End date

A3 Weekday to count between A1 and A2 (1=Sunday)

Formula: =INT((A2-MOD(A2-A3,7)-A1+7)/7)

Alternative Formula (by Daniel M.): =INT((A2-WEEKDAY(A2+1-A3)-A1+8)/7)

Example: You have several options to calculate how many Wednesdays and Fridays are between 1-Jan-2013 and 15-Apr-2013:

Put the start date into A1 and the end date into A2.

Solution 1: =INT((A2-MOD(A2-4,7)-A1+7)/7)+INT((A2-MOD(A2-6,7)-A1+7)/7)

Solution 2: array-enter =SUM(INT((A2-MOD(A2-{4,6},7)-A1+7)/7))

Solution 3: =SUMPRODUCT(INT((A2-MOD(A2-{4,6},7)-A1+7)/7))

The result is in all cases: 30

Please notice that 4 stands for Wednesday and 6 for Friday. If you like to add other or additional weekdays change {4,6} accordingly. If you want to count more than 3 weekdays you might prefer to subtract the sum of the remaining weekdays from end date - start date + 1.