VESA Mount Sizes, Explained Before You Buy

VESA is the reason you can put almost any monitor on almost any arm, and it is also the reason a small minority of monitors will not go on any arm at all. The standard itself is unglamorous: a square or rectangular pattern of four threaded holes on the back of a display, at agreed spacings, so mounts and panels from different manufacturers fit each other. Everything that goes wrong with mounting a screen comes down to four questions about that pattern and the metal around it, and all four are answerable in about a minute with a tape measure.

This is the reference page for the two roundups where the question keeps coming up — single monitor arms and dual monitor arms— so you can check compatibility before you spend rather than during the return window.

What the numbers actually mean

A VESA size is written as two numbers in millimeters: the horizontal spacing between hole centers, then the vertical. 100 x 100 means the four holes form a 100mm square. 200 x 100 means they form a rectangle 200mm wide and 100mm tall. The numbers describe hole centers, not the size of the plate, the screen, or anything else — which is why measuring between the outer edges of the holes gives you a slightly wrong answer and measuring center to center gives you the right one.

The sizes you are realistically going to meet on a desk monitor are a short list. 75 x 75 appears on small and light panels, typically under about 24 inches. 100 x 100 is the overwhelming default for desk monitors and what nearly every desk arm ships to fit. 200 x 100 and 200 x 200 turn up on large or heavy panels, including some 32-inch and larger displays and many televisions. Larger patterns exist above that, but they belong to wall mounts and screens far past desk scale.

Most desk arms are sold as fitting 75 x 75 and 100 x 100, and the good ones include a plate with both patterns drilled. If your monitor is 200 x 100, you do not need a different arm so much as an adapter plate that presents a 100 x 100 pattern to the arm and bolts to the 200 x 100 holes on the panel — provided the arm’s weight rating covers the heavier screen, which is usually the real constraint.

How to measure yours in ten seconds

Look at the back of the monitor. If it has a removable stand, the four holes are frequently hidden behind it, so pop the stand off first — most release with a button or a single screw. You are looking for four threaded holes in a square or rectangle, usually near the middle of the panel.

Measure from the center of one hole to the center of the hole beside it for the horizontal number, then center to center vertically. If both come out near 100mm, you have 100 x 100. Near 75mm both ways, 75 x 75. If the horizontal is roughly double the vertical, you are looking at 200 x 100. The spacings are far enough apart that you do not need precision — nothing sits between 75 and 100, so a rough measurement is decisive.

Note the screw thread as well. Smaller patterns typically use M4 screws and larger ones M6 or M8, and arms ship with an assortment. The failure mode here is length rather than diameter: a screw that is too long bottoms out before it clamps, and on some panels it can reach the electronics behind the mounting boss. If the supplied screws will not tighten, use the spacers in the box rather than forcing them.

Trap one: the weight rating is a range, not a maximum

Gas-spring arms are the ones worth having, and they work by balancing the screen’s weight against a spring you tension to match. That means they have a minimum as well as a maximum. A very light panel on an arm rated for heavy screens will drift upward and refuse to stay where you put it, even at the spring’s lowest tension — the same failure as overloading, in the other direction.

Weigh the monitor without its stand, since the stand is often a large fraction of the boxed weight and does not come along. Then check that the figure lands inside the arm’s stated range with a little room at each end. On a dual arm, check whether the rating is per arm or for the pair; manufacturers state it both ways, and reading a per-pair number as a per-arm number is a common way to end up with two sagging screens.

Trap two: depth, curve, and the clamp

A pattern that matches does not guarantee a fit. Three physical details decide the rest. The first is how deeply the holes are recessed: some panels sink the mounting boss into a hollow, and an arm’s plate has to reach into it. Where it cannot, a spacer kit solves it, and better arms include one.

The second is curvature. A curved panel has a curved back, so a large flat mounting plate may contact the panel before the screws seat. Arms sold as curved-compatible use a smaller or shaped plate for exactly this reason, and it is worth checking if you are mounting a 34-inch or wider curved screen.

The third is the desk end. A clamp needs an unobstructed edge and a worktop within its thickness range, and the two things that defeat it are a desk with a lip or a frame rail right at the back edge, and a top thicker than the clamp opens. A grommet mount is the alternative where the clamp cannot bite. Both matter more on standing desks, whose frames often run steel exactly where you wanted the clamp to go.

Trap three: the monitor with no VESA pattern

A meaningful minority of consumer monitors, particularly slim design-led models and some all-in-one machines, ship with no VESA holes at all. There is no fix that is as good as a real pattern. Adapter brackets exist that grip the panel around its edges or bolt to the original stand’s mounting point, and they work, but they add bulk, they load the panel in a way it was not designed for, and they rarely feel solid.

The honest advice is to treat a VESA pattern as a buying requirement rather than a nice-to-have. If you expect to put a screen on an arm at any point — and on a multi-monitor desk you almost certainly will — check the specification sheet for a VESA line before you buy the monitor, not after.

A short pre-purchase checklist

Before you order an arm, confirm five things: the pattern on the back of your monitor measured center to center; the weight of the panel with the stand removed; that the weight sits inside the arm’s range, per arm if it is a dual; whether your panel is curved or deeply recessed, and whether the arm handles that; and whether your desk edge suits a clamp or needs a grommet. Five checks, one tape measure, and the whole category of mounting problems goes away.