[ecfisa]

Hola jars.

Proba si te funciona de este modo:

Código Delphi [-]
function GetFileSizeEx(hFile: THandle; var lpFileSize: Int64): BOOL; stdcall; external 'kernel32.dll';

function GetHugeFileSize(aFileName: TFileName): Int64;
var
  hnd : THandle;
begin
  hnd := CreateFile(PChar(aFileName),
                    GENERIC_READ,
                    0,
                    nil,
                    OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,
                    0);
  if not GetFileSizeEx(hnd, Result) then
    RaiseLastOSError;
end;

// Ejemplo de llamada:
...
begin
  ShowMessage(IntToStr(GetHugeFileSize('C:\...\Nombre_Archivo.Ext')));
end;

Minimum supported server Windows Server 2003 [desktop apps only] (GetFileSizeEx)

Saludos