Thank you for elaborating on this.
We are now able to reproduce the described behavior -- it is caused by the fact that the AutoLayout works with relative percentage values when calculating the necessary margins for the PlotArea. Unfortunately, for extreme cases as this one (Height=4800 pixels), the percentage value becomes quite large as well and that is why you see the whitespace gaps at the top and the bottom of the chart.
We will forward your feedback to our developers so they can consider improving the automatic behavior for future versions of the control but for the time being you would need to disable the AutoLayout feature and set the PlotArea margin values manually like this:
DataTable table =
Random random =
i = 0; i < 300; i++)
DataRow row = table.NewRow();
"Label number "
] = random.Next(0, 1000);
Telerik.Charting.Styles.ChartMargins(15, 100, 30, 50);
RadChart1.Height = 600 * 8;
RadChart1.SeriesOrientation = ChartSeriesOrientation.Horizontal;
RadChart1.DataSource = table;
the Telerik team