'Use Excel Number Formats to format bytes as KB or MB or GB.

'Select the range and apply the following number format:
[<1000000]0.00," KB";[<1000000000]0.00,," MB";0.00,,," GB"

'Or for Excel versions that use the comma as the decimal separator:
[<1000000]#.##0,00" KB";[<1000000000]#.##0,00.." MB";#.##0,00..." GB"