An UDF to calculate weekday

It seems feasible .

Function myweekday(ByVal y As Long, ByVal m As Long, ByVal d As Long) As Long Dim bias As Long If m > 2 Then bias = m - 2 Else bias = 10 + m y = y - 1 End If myweekday = (d + (13 * bias - 1) \ 5 + (y Mod 100) + (y Mod 100) \ 4 + (y \ 100) \ 4 - 2 * (y \ 100)) Mod 7 + 1 End Function