Ergotron LX Single vs Dual: The Decision Is Simpler Than You Think
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Most people frame this as a features question. It's actually a commitment question. The single arm lets you start with one screen and add a second independently later. The dual arm locks you into a specific two-screen configuration from day one, on a single mounting point, at more than double the price of one single arm — and slightly more than two singles combined.
That framing changes the math considerably.
The Ergotron LX Single Monitor Arm
The LX Single is Ergotron's workhorse. It's been the go-to recommendation across published ergonomic and home-office review coverage for years, and the owner review volume backs that up — north of 10,000 ratings with a 4.7-star average is a signal that something is consistently not failing people. The mechanical design centers on a patented CF (constant force) spring mechanism that's user-adjustable with a hex key, which means it actually holds position as your monitor ages and gets heavier from accumulated stand-alone hardware or lighter if you swap panels.
Spec-sheet range is 20 inches of height adjustment, a reach of up to 32 inches from the post, and a rated capacity of 7 to 25 lbs. VESA compatibility covers 75×75mm and 100×100mm patterns. The clamp handles desk surfaces up to 3.18 inches thick.
The Ergotron LX Dual Monitor Arm
The Dual LX runs both screens off one vertical post and one desk clamp. That's its pitch: one clamp footprint, two screens. The arm segments are the same LX-quality construction as the single, with the same CF spring tensioning per arm and the same VESA compatibility. Published owner feedback — 445 ratings at 4.5 stars — is positive but notably thinner than the single, which matters: fewer reviews means less signal on edge-case failure modes.
The tradeoff that shows up consistently in owner reports is rigidity. A single clamp bearing the combined load of two monitors and two full arm assemblies puts more stress on the desk edge interface. Reports of micro-wobble when both screens are extended near full reach appear more often in the Dual's one-star reviews than in the Single's. Assembly complexity is also higher — published estimates from owners typically run 45–60 minutes versus 20–30 for the single.
Head-to-Head: Where They Actually Differ
Stability Under Load
The Single wins this cleanly. One arm, one clamp, one monitor — the physics are simpler and the failure modes are fewer. Based on long-term owner reports, the Dual's single-post design introduces more leverage torque on the clamp when both arms are extended. If your desk edge is thick, solid wood or a proper steel frame, it's manageable. If you're on a laminate IKEA surface with a softer core, wobble is a real risk with the Dual that's almost never reported with the Single.
Positioning Independence
Two singles beat one dual here, and it's not close. With two separate arms on separate clamps, each screen can be repositioned independently — one eye-level for your primary, one slightly lower and angled for reference, different depths, different heights. The Dual couples both screens to a shared post, so gross height adjustments affect both, and the range of independent positioning is more limited. If your workflow involves dramatically different screen heights or you frequently reconfigure, the dual is the worse tool.
Desk Real Estate
This is where the Dual earns its keep. One clamp instead of two means less desk-edge commitment — relevant if you're running a narrower desk or want to preserve a specific edge section for something else. Two singles require two separate clamp placements, which can crowd a 48-inch or shorter surface.
Price-Per-Arm
At typical prices (~$200 for the Single, ~$439 for the Dual), two singles run approximately $400 versus one dual at $439. The Dual costs about $39 more than two singles for a less flexible, less independently adjustable configuration. That derived metric is the most honest number in this comparison — and it largely explains why the Dual is a niche rather than a mainstream recommendation.
At a Glance
| Ergotron LX Single | Ergotron LX Dual | |
|---|---|---|
| Typical price | ~$199.99 | ~$438.99 |
| Monitors supported | 1 | 2 |
| Weight capacity | 7–25 lbs per arm | 7–25 lbs per arm |
| Height adjustment | 20 in | 20 in |
| Max reach | 32 in from post | 32 in per arm from post |
| Clamp footprint | 1 per monitor | 1 for both monitors |
| VESA compatibility | 75×75, 100×100mm | 75×75, 100×100mm |
| Price per arm (derived) | ~$200 | ~$219 (+~10% vs single) |
| Owner review volume | 10,928 ratings | 445 ratings |
| Avg. owner rating | 4.7★ | 4.5★ |
| Assembly time (owner reports) | 20–30 min | 45–60 min |
Which One Is For You
Buy the Ergotron LX Single (and potentially a second one separately) if you want maximum positioning flexibility, plan to run two different-sized monitors, have a desk shorter than 55 inches, or aren't certain you'll always run dual screens. Two singles give you more options at nearly identical cost.
Buy the Ergotron LX Dual if your desk edge is genuinely congested — you need every inch of clamp-free surface you can get — and you're committed to a matched, symmetrical dual-monitor setup that won't move much once it's configured.
Skip both if your desk surface is particleboard or thin laminate under 3/4 inch — neither arm's clamp will hold reliably at the leverage these arms exert. Look instead at a freestanding monitor riser or a desk with integrated grommet mounts.
Bottom Line
The Ergotron LX Single is the right call for most buyers, including most people who want two monitors — because two singles cost less than one dual, give you better independent positioning, and carry significantly more real-world owner validation. The Dual is a legitimate tool for a specific scenario: one clamp slot, two screens, symmetric setup, solid desk. If that's you exactly, it delivers. If you're not sure, the single is the safer, more flexible, cheaper bet.
For more context on building a complete ergonomic workstation, see our guide on ergonomic workstation setup.