How to Measure a Monitor Arm for Your Desk

Buy a monitor arm only when the screen is in the wrong place and you have three numbers that match a manufacturer spec. If the monitor’s own stand already puts the screen in the viewing band below, you do not need an arm.

The viewing band

The Canadian Centre for Occupational Health and Safety says the seated sight line should fall between horizontal and 30 degrees below horizontal, which it describes as eye level or slightly below. In the standing position, it says the monitor should still sit between horizontal and 35 degrees below. Measure your eye height while seated and while standing, at the distance you actually sit from the screen. The arm has to reach both heights if you raise and lower the desk. An arm that only works at one desk height fails the standing setup.

Three numbers from your desk and monitor

1. Desk thickness at the clamp. Measure the top where the clamp will close, not at the middle of the desk if the edge is thinner or has a lip. Write down the lip height as well. A clamp range that ignores a bar or a cable tray is the usual miss.
2. Clearance behind the top. Measure from the rear edge to the wall, a shelf, or a window. The arm’s base and the monitor’s swing need that space.
3. Monitor weight and hole pattern. Use the monitor maker’s spec for weight, without the stand if the stand comes off. On the back of the monitor, measure the distance between the mounting holes. Common patterns are a square of holes. Do not assume the pattern. Read it off the monitor or its spec page, then match it to the arm’s stated plate.

Take those three numbers to the arm maker’s current page. You need a clamp range that includes your thickness, a weight limit above the monitor’s stated weight, and a VESA plate that matches the holes. If any one of those is missing from the listing, you cannot tell whether the arm fits.

Named arms on this site

Three HUANUO arms have pages. FlowLift’s title covers one screen. HNDS7’s title covers two screens. TitanLift’s title covers one screen up to 49 inches and 44 lbs. Clamp thickness and arm reach are not in those titles, so none of them is described as a fit until you measure. Compare them in HUANUO monitor arms.

When not to buy

Skip the arm when:

• The monitor stand already places the screen in the seated and standing bands above.
• The desk edge is thicker than every clamp range you are willing to consider, or a lip blocks the clamp.
• The monitor has no VESA holes. An adapter is a second product, with its own weight, and it still has to fit the arm’s weight limit.
• The wall behind the desk is closer than the arm needs to tilt. Forcing the screen flat against a wall is not an adjustment.

Screen height is part of the desk decision. If you have not measured elbow height yet, start with how to measure a standing desk. The keyboard still has to sit in front of the screen with straight wrists, which is covered in how to choose a keyboard and mouse.