Measure the mounting position, not just the tabletop.
A thickness range match answers one question. Permission, construction and access are separate checks.
How much clearance does a monitor arm need?
Use the exact clamp drawing and installation instructions. This catalog does not establish one universal setback, wall gap or underside clearance for all six kits. Measure the actual contact pads, screw or handle travel, assembly access and any rear arm movement before choosing a mounting point.
1. Thickness at the contact point
Measure between the surfaces the clamp actually bears on. An apron, bevel, frame or underside rail may make the nominal desktop thickness misleading. Compare the result with the supplied clamp’s range and mounting position.
2. Flat bearing area and access
Inspect above and below for a frame, drawer, cable tray, shelf or sloped edge. A thickness match does not show that the pads can sit flat or that the screw can be reached and tightened as instructed.
3. Desktop permission and construction
Check the exact desktop maker’s guidance. A general desk load rating is not permission for a concentrated clamp load, and choosing “solid” does not establish a safe installation.
The recorded US exception is IKEA LAGKAPTEN / ADILS desk S29416758 (white 47 1/4x23 5/8 in): IKEA US product page: not suitable for installation of a screen stand; top uses honeycomb paper filling. That result is tied to the recorded SKU and market, not every IKEA product. Adding a reinforcement plate does not override a manufacturer prohibition in this checker.
4. Movement and cables
Trace the actual arm, display and cable route through the intended movement. A clear stationary clamp contact does not establish rear swing clearance, cable slack or clearance during desk-height changes.
Recorded clamp ranges, with the version caveat
| Exact desk-arm kit | Published load | Depth / scope condition | C-clamp thickness | Evidence |
|---|---|---|---|---|
| Ergotron HX with HD Pivot (45-647-224)US · 45-647-224 | 12.7–19.1 kg | 152–304 mm; 1000R scopeOther installation conditions still apply. | 10–66 mmCurrent HX clamp drawing has two installation positions:10-41mm and28.5-66mm. Confirm your supplied clamp revision; older attachment guides show16-66mm. | Load / product Clamp drawing |
| Ergotron HX with VHD Pivot (45-693-224)US · 45-693-224 | 13–17 kg | 231–351 mm; 1000R scopeOther installation conditions still apply. | 10–66 mmCurrent HX clamp drawing has two installation positions:10-41mm and28.5-66mm. Confirm your supplied clamp revision; older attachment guides show16-66mm. | Load / product Clamp drawing |
| Mount-It Heavy-Duty Single Monitor Arm (up to 49 in)US · MI-4881 | 2–19.9 kg | Published screen range 17–49 inOther installation conditions still apply. | 10–84 mmThickness alone does not approve the desktop. | Load / product |
| Ergotron LX — 2-piece clamp (45-241-224)US · 45-241-224 | 3.2–11.3 kg | Above 89 mm: capacity needs clarificationAbove 9.1 kg, vertical travel can be reduced. | 10–60 mmThickness alone does not approve the desktop. | Load / product |
| Ergotron HX — standard pivot (45-475-026)US · 45-475-026 | 9–19 kg | Above 150 mm: capacity needs clarificationOther installation conditions still apply. | 10–66 mmConfirm supplied HX clamp matches2024drawing. Two mounting positions cover10-66mm; olderguide16-66mm. | Load / product Clamp drawing |
| VIVO STAND-V101G1U — USB single armUS · STAND-V101G1U | 0.998–14.969 kg | Regular ≤32 in; ultrawide ≤49 inOther installation conditions still apply. | 10.16–83.82 mmThickness alone does not approve the desktop. | Load / product |
These are C-clamp thickness ranges. Do not reuse them as grommet-hole diameters or assume a different mounting kit has the same range. For HX, check the drawing and supplied revision; for LX, the recorded two-piece clamp is not the low-profile top-mount kit.
Check my screen, arm and desktop →Manufacturer evidence
Published specifications are the basis of these checks. We have not physically tested these installations. Sources apply to the recorded US configuration unless noted.
- IKEA — LAGKAPTEN / ADILS S29416758 US product guidanceReviewed 2026-10-25
- Ergotron — HX clamp dimension drawingReviewed 2026-10-26
- Ergotron — LX 45-241 product specificationsReviewed 2026-10-26
- Mount-It — MI-4881 product specificationsReviewed 2026-10-25
- VIVO — STAND-V101G1U product specificationsReviewed 2026-10-26