Measure the space you actually use
Record your desktop's clear width and depth, then mark anything that already occupies it: a lamp base, monitor stand, speakers, or a charging station. Measure from the inside of any raised edges. A desk sold as 48 inches wide may have less useful space once permanent objects are accounted for. Sketch the surface as a rectangle and label the measurements.
Next, sit down with your normal keyboard and mouse. Outline the area your hands use on paper. That area is a working space, not spare capacity for a stand. If a proposed accessory fits only when the mouse is pushed to the edge, revise the arrangement before buying.
Inspect the edges and the underside
For a clamp, record the tabletop thickness at the intended mounting point. Look underneath for a rear apron, drawer, cable tray, or steel frame. Record how far these obstacles sit from the edge. Photograph the area with a ruler in the picture so you can compare it with a manufacturer's installation drawing.
Measure the gap to the wall separately. Access for the clamp screw and space for a moving arm are different requirements. Do not assume that a clamp that can be installed will allow the screen to sit in your preferred position.
Make a purchase brief
Write down the problem in one sentence: 'I need the space occupied by the monitor feet for a notebook,' for example. Add the measurements, the display model, and any restrictions on drilling or attachments. Now every candidate has a clear job to do.
Before ordering, lay out paper rectangles for the new equipment. Keep the mock-up in place for a normal work session. If your existing arrangement works after simply moving a lamp or storing a charger, keep the money. If it does not, your notes explain which dimension the purchase must improve.
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.