Separate three measurements
Desktop depth, display depth, and your viewing position are different measurements. A screen can physically fit on a shallow desk while its stand leaves little room for a keyboard. An arm can remove the feet from the desktop while placing the screen farther forward than expected.
Start with a side-view sketch. Mark the back of the desk, the front edge, the monitor's intended screen plane, and the space for your input devices. Use the actual assembled dimensions from the product drawing where possible.
Try a simple depth budget
Imagine a 24-inch-deep surface. If a stand and its required placement occupy the rear 9 inches, 15 inches remain in front of that footprint. This subtraction describes free surface only. It does not establish a recommended viewing distance or prove that a particular monitor is suitable.
Repeat the exercise with your current equipment. A keyboard can sometimes slide under an elevated shelf, but only if the opening is tall and wide enough and you do not need that space while typing. Avoid counting the same area twice.
Test the position before choosing hardware
Place a sheet of cardboard where you expect the screen to sit and check the arrangement from your normal chair position. Keep text at the size you normally use on your current display; shrinking everything to make a layout seem comfortable is not a useful test.
If the proposed screen needs to sit farther back, inspect the complete mount geometry. A maximum extension measurement tells you how far an arm reaches, not how closely it retracts. If no acceptable layout exists, changing display size or desk position can be more useful than buying another accessory.
About this guide
Worked examples are illustrative calculations, not measurements from product testing. Follow the instructions for your exact equipment. Read our research and correction policy.