Business days in Excel: NETWORKDAYS and WORKDAY

The built-in functions, their weekend codes, and where the holiday data comes from.

The functions

=WORKDAY(A2, 10, Holidays!A:A)          ' add 10 business days
=NETWORKDAYS(A2, B2, Holidays!A:A)      ' count between dates (inclusive)
=WORKDAY.INTL(A2, 10, 7, Holidays!A:A)  ' weekend code 7 = Fri-Sat
=NETWORKDAYS.INTL(A2, B2, 7, Holidays!A:A)

Weekend codes for .INTL

Code	Weekend
1	Saturday, Sunday (default)
7	Friday, Saturday
11	Sunday only
17	Saturday only

Plain WORKDAY and NETWORKDAYS always use Saturday-Sunday.

The holiday range

Excel ships no holiday data; the Holidays!A:A range is yours to fill and maintain, including substitute days. Two ways to fill it:

Paste from the holiday calendar generator, or import CSV directly:

https://dierum.io/v1/holidays.csv?region=GB&year=2027&api_key=YOUR_KEY

In Excel: Data → From Web, paste the URL. Refresh the query each January.