Convert the Filesize in a Number into String Format

Option Explicit

' Add a module and copy paste this function.
' To test this function, call this function from Immediate window by passing
' file size to it.  e.g. ?GetFileSizeString(1000), GetFileSizeString(10000)

Private Declare Function StrFormatByteSize Lib "shlwapi.dll" Alias "StrFormatByteSizeA" _
(ByVal dw As Long, ByVal szBuf As String, ByVal uiBufSize As Long) As Long

Private Function GetFileSizeString(ByVal lngFileSize As Long) As String
    Dim strBuff As String

    strBuff = Space$(100)
    StrFormatByteSize lngFileSize, strBuff, Len(strBuff)

    GetFileSizeString = Replace(Trim$(strBuff), vbNullChar, "")
End Function