So here's the scenario. I was looking to have the a panel with exact dimensions on a C# form (700x400). I wanted even and default spacing around the panel on the form. I figured out the default spacing was 12, so I set the size of the form to 724x424, only to find that something still looked wrong.

Turns out that the dimensions of the form include the border and title bar (seems obvious in retrospect, doesn't it). What I really wanted was to have the form's ClientSize equal to 724x424. To figure out what I needed the form dimensions to be in order to have a correctly-sized Client area to place my frame in, I used the following snippet:

MessageBox.Show(String.Format("{0}, {1}",
                              this.Width - this.ClientSize.Width,
                              this.Height - this.ClientSize.Height));

The final result:

The frame takes up 16 pixels horizontally (8 on each size) and 38 vertically (8 on the bottom and 30 on top), so the final size of the form I needed was 740x462.