How to Measure VESA

Almost every failed monitor mount comes down to one of three numbers being wrong. This page covers all three. It takes about two minutes and a ruler.

1. Your VESA pattern

Look at the back of your monitor. You are looking for four screw holes arranged in a square or a rectangle, usually in the middle, sometimes hidden under a plastic cover or behind the stand.

Measure centre of hole to centre of hole, horizontally first, then vertically. Measure in millimetres. VESA is a metric standard and it is metric in the United States too. A tape measure with a millimetre edge is fine.

You will get one of these:

75 x 75 mm - small monitors, around 15 to 22 inches
100 x 100 mm - by far the most common, roughly 19 to 32 inches
200 x 100 mm or 200 x 200 mm - large monitors and small televisions
400 x 200 mm, 400 x 400 mm and up - televisions

If you measure something that is not on that list, measure again. You are probably measuring hole edge to hole edge instead of centre to centre.

What if there are no holes

Plenty of monitors, and almost every iMac and all-in-one, have no VESA holes. You are not stuck. A VESA adapter bracket clamps around the monitor body or bolts to its existing stand mount and gives you a standard 75 or 100 mm plate to work with. Check the adapter's own size and weight limits before you buy it.

2. Your monitor's weight

This is the number people skip, and it is the one that breaks things.

Find your monitor's model number on the sticker at the back and look up its spec sheet. You want the weight without the stand, because the stand is coming off. It is usually listed as "weight excluding stand" or "panel only". If you can only find the weight with the stand, subtract roughly 2 to 4 lbs for a typical desktop monitor, then check it against the arm's limit with room to spare.

Gas spring arms have a minimum weight as well as a maximum, and the minimum is real. Put a 3 lb monitor on an arm rated from 4.4 lbs and the spring will push it to the top and hold it there. If your monitor is very light, choose a mechanical spring or a tension arm instead.

3. Your desk

A desk clamp needs an edge it can grip. Measure the thickness of the desktop at the point where the clamp will sit, and check there is nothing in the way underneath: no cross brace, no cable tray, no drawer runner in the first few inches.

Glass desks and thin floating shelves are the usual problem. Glass can take a clamp but it needs a rubber pad and a cautious tightening. Anything under about half an inch thick, or unsupported, is better served by a grommet mount through an existing hole, or by a wall mount.