IF criteria - cell characteristics

davidbutov 

No, you'd need VBA for that. Here is a user-defined function that you can copy into a module in the Visual Basic Editor:

Function SumBold(rng As Range) As Double
    Dim cel As Range
    Application.Volatile
    For Each cel In rng
        If cel.Font.Bold Then
            SumBold = Application.Sum(SumBold, cel.Value)
        End If
    Next cel
End Function

You can then use it in a formula such as

=SumBold(A1:A10)

You'll have to save the workbook as a macro-enabled workbook and allow macros when you open it.

Warning: the formula result will not be updated automatically when you toggle the Bold property of a cell. It will be updated the next time Excel recalculates any formula. You can press F9 to update it immediately.