Real width

Hi all,
        I have confronted with difficulties with strings in element. i have next situation, need receive real width of string that occupy on a page.
        How can i receive real width?
        I have following code:

public class GridTest : CompositeDataBoundControl
{      
     protected override int CreateChildControls(IEnumerable dataSource, bool dataBinding)
        {
            Table table = new Table();
            TableRow row = new TableRow();
            table.Rows.Add(row);
            TableCell cell = ...