Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

// Derive a new Type: TMyDBGrid 

type
   TMyDBGrid = class(TDBGrid)
   public
     property DefaultRowHeight;
   end;

 var
   Form1: TForm1;

 implementation

 {$R *.DFM}


 procedure TForm1.FormCreate(Sender: TObject);
 begin
   DbGrid1.Canvas.Font.Size := 13;
   TMyDBGrid(DBGrid1).DefaultRowHeight := DBGrid1.Canvas.TextHeight('MMMMM') + 4;
 end;