Get Filesize in Bytes

// uses sysutils
function pwGetFileSize(const FName: string): Int64;

var

SearchRec: TSearchRec;

begin

if FindFirst(ExpandFileName(FName), faAnyFile, SearchRec) = 0 then

begin

  Result := SearchRec.Size;

  FindClose(SearchRec);

end

else Result := -1;

end;