Monitor Arms

The spec that decides it is the minimum, not the maximum

Every monitor arm advertises how much weight it holds. That is the wrong end of the number.

A gas-spring or counterbalanced arm is a spring fighting gravity. Load it below its minimum and the spring wins: the arm drifts upward and will not stay where you put it. The Ergotron HX is rated 20–42 lb— that 20 lb floor means it will simply not hold a normal 27″ monitor down. Most listings print “42 lb” and stop.

So read the range. And note the trap in the middle of the Ergotron line: the LX Pro is not a straight upgrade on the LX. It has a lower maximum (22 lb vs 25) and a lighterminimum (4 lb vs 7). Which is better depends entirely on your monitor, which is the opposite of what “Pro” implies.

The exception worth understanding

Not every arm has a minimum, and the ones that do not are not being sloppy. A non-counterbalanced mount — where you clamp the arm to a pole at a fixed height — has no spring to overcome, so there is no light-monitor failure mode and no minimum to publish. When a manufacturer publishes a maximum only, check whether it is a gas spring before you assume the spec is incomplete.

How the category divides

By mechanism: gas spring (pneumatic, adjusts with a finger), mechanical spring counterbalance (Ergotron calls theirs Constant Force; Humanscale uses a weight-compensating spring), or plain friction and clamps. The difference is here, and it decides both the minimum-weight problem above and how often you will re-tension it.

By what it carries: a single arm, a dual mount, or a heavy-duty arm for an ultrawide. The ultrawide field is thin, and honestly so: very few arms are rated for that weight at that leverage.

By what the money buys: the clearest test of that is the Ergotron LX against the Amazon Basics gas-spring arm — eight times the price, the same two VESA patterns, and one published spec where the cheap one wins.

And the first question, before any of that: do you need an arm at all? A fixed monitor stand costs a fraction and needs no VESA or clamp, but it only raises the screen a set few inches — the honest arm-versus-stand comparison is here.

VESA, in one paragraph

VESA’s mounting standard is a set of hole patterns on the back of your monitor. Most desktop monitors are 75×75mm or 100×100mm, both of which VESA calls MIS-D. Bigger and heavier screens use MIS-E (200×100mm, six holes) or MIS-F. The thing worth knowing: screen size is not the primary compatibility criterion — hole pattern and weight are. A 34″ monitor that weighs 12 lb is an easier problem than a 27″ that weighs 25. The full guide is here, including the arithmetic error we found in a major manufacturer’s own VESA table.

What the money buys

Warranty and adjustment quality. The range here runs from one year to fifteen. It also buys a real spec sheet: the premium brands publish weight ranges, lift distances, tilt angles and cycle-test counts, while the budget end frequently publishes a maximum and a photograph.

A caution on those cycle tests: where they exist, they are the manufacturer’s owninternal tests, and they measure different things. One brand’s 10,000-cycle motion test and another’s 20,000-cycle gas-spring test are not comparable, and neither is a third-party standard. In fact not one arm we looked at claims conformance to any external safety or durability standard — VESA is a mounting interface, not a durability rating.

The mistake people make

Buying the arm before checking what the monitor weighs — the weight withoutthe stand — and what pattern it uses. Both are on the manufacturer’s spec page and take thirty seconds. Then remember that an arm changes your monitor height, which means setting it correctly — and the popular “top of screen at eye level” rule turns out to be the weaker of the two positions in the literature.

And before the arm question, there is a bigger one: one screen or two. Two monitors cannot both sit centered on your eye line, which changes both the mount you need and the desk depth it takes.