Ergotron HX vs LX

Buy the LX unless your monitor weighs more than 20 pounds without its stand, is wider than 34 inches, or uses a VESA pattern bigger than MIS-D. If it does any of those, the HXis not an upgrade you are treating yourself to — it is the only one of the two that will work.

Here is why that is the whole comparison, in one line of arithmetic.

Two windows, five pounds of overlap

Ergotron publishes a minimum and a maximum for both arms, which already puts it ahead of most of this category:

LX: 7–25 lb. HX: 20–42 lb.

Lay those over each other and the shared band is 20 to 25 lb— five pounds, inside which either arm is rated for your screen. Outside it, one arm is rated and one is not, and “not rated” here does not mean “slightly worse at it”. A counterbalanced arm holds position because its spring tension matches the load. Over the ceiling, the load wins and the monitor sinks. Under the floor, the spring wins and the monitor rises to the top of its travel and stays there, with the tension screw already wound to its stop.

That is the part that catches people out, because the mental model for “too heavy” is obvious and the mental model for “too light” usually is not. We cover the mechanism in gas spring vs mechanical arms, and the symptom in how to fix a sagging monitor arm — which is the same mismatch pointing the other way.

Which side of the line is your monitor on?

Twenty pounds is more monitor than most desks have on them. A typical stripped 27-inch panel sits in single or low double digits; the Dells and ASUS panels we researched for our monitor roundup publish panel-only weights from about 9.9 lb to about 14.8 lb for 27 and 32-inch screens. All of those are inside the LX window and under the HX floor.

The figure you need is the weight with the stand removed, and it is frequently several pounds below the number on the box, which includes a stand you are about to throw in a cupboard. How much does a monitor weigh collects the published panel-only figures we could verify and explains how to weigh yours if the maker does not print one. Do that before you read another spec on either arm.

If the answer lands between 20 and 25 lb — a heavy 38-inch ultrawide, a 40-inch panel, a monitor with a built-in webcam and speaker bar — you are in the overlap and both arms are rated. In that narrow case, buy on the other columns: the LX has more lift and a cycle figure, the HX has more headroom above you and wider VESA support.

What the HX gives you that the LX cannot

Three things, and they are specific rather than general.

1. Screen size to 49″. The LX is rated to 34 inches. If your display is wider than that, the comparison is over regardless of weight.

2. MIS-E and MIS-F.The HX is the only arm across our monitor-arm pages that supports the six-hole MIS-E and the large MIS-F patterns; the LX covers MIS-D at 75×75 and 100×100, which is what nearly every consumer monitor uses. VESA patterns and weight ratings shows how to tell them apart on the back of your own screen.

3. A 42 lb ceiling. Which is enough for essentially any consumer ultrawide, and is the reason the HX appears at the top of our heavy-duty roundup — a short page, because very little else is rated this high.

What it does not give you is longer travel. 11.5″ of lift against the LX’s 13″: the bigger arm moves less, which is worth knowing if the reason you are mounting a screen at all is getting it down to your eye line.

What they share, and the one disclosure that differs

Both carry a 10-yearwarranty published by Ergotron rather than implied by a retailer, which is longer than most of this category and a real part of what you are buying. Neither claims a third-party standard — no UL, ANSI or BIFMA statement appears in the documents we read for either arm.

The difference is a cycle figure. Ergotron publishes 10,000 cyclesof motion for the LX and publishes nothing equivalent for the HX. We label that every time we cite it: it is Ergotron’s own internal test, not an independent certification, so it is a disclosure rather than a proof. But a company printing a durability number for one product and not for its heavier sibling is information, and on two arms with identical warranty terms it is the only thing separating them on longevity.

Before you order either one

Weigh the panel without its stand. Identify the VESA pattern. Then check the desk, which is the step people skip: both arms clamp or grommet-mount to an edge, and the thickness window is the figure Ergotron does not publish anywhere we can fetch and cite. We will not print a number we traced only to retailers, so will a monitor arm fit my desk and clamp vs grommet mounting both handle it the honest way: measure your edge, check the clearance behind it, and know which mounting method your desk actually allows.

If the desk is glass, or the top is thinner or thicker than a clamp expects, that is a separate decision and it comes before the arm — a monitor arm on a glass desk is where we work through what can and cannot be done safely.

What we can’t tell you

We have not mounted either of these arms. Everything above is Ergotron’s own published specification, cited and dated, and the arithmetic of laying two weight windows over each other. We cannot tell you how either arm feels to reposition after two years, whether the HX’s extra mass makes a desk flex, or whether a 10,000-cycle test corresponds to anything in your room. Those need time and a monitor. What the published figures can settle — which arm will physically hold your screen where you put it — is the question most buyers of these two arms get wrong, and it is answerable before you spend anything. Our methodology sets out where our evidence stops.