Monitor Arm or New Monitor? Check the Screen Position First

A monitor’s specification sheet describes the image: size, resolution, refresh rate, panel type. Whether you are comfortable in front of it for a working day depends mostly on where the screen sits relative to your eyes, and that is a property of the stand or arm, not the panel. This guide sets out what the published workplace guidance says about screen position, what a stock stand can and cannot do according to the manufacturer’s own datasheets, what a desk-mounted arm adds, and what to check for compatibility before spending anything.

It is not a hands-on review and it makes no claim about what any arm did for anyone’s neck. Correction, September 23, 2026: the earlier version of this post described two years of monitor, chair and arm purchases, a £90 price, and neck complaints that faded afterwards. None of that was documented and it has been removed.

Illustration only; the image is not a product photograph or evidence of testing.

What the placement guidance actually says

Two public bodies publish specific, free guidance on where a screen should be. The US Occupational Safety and Health Administration (OSHA) keeps a computer-workstation eTool, and the Canadian Centre for Occupational Health and Safety (CCOHS) publishes a fact sheet on positioning the monitor. Both were read on September 23, 2026. CCOHS marks its page as revised November 29, 2022 and confirmed current July 21, 2025.

Question	OSHA computer-workstation eTool	CCOHS “Positioning the Monitor”
Distance from eye to screen	“at least 20 inches”; preferred range “between 20 and 40 inches (50 and 100 cm)”	“40 to 74 cm”; “an arm’s length is usually a good estimation”
Height of the top of the screen	“at or slightly below eye level”	at or slightly below eye level; a high monitor “is a source of discomfort”
Where the centre of the screen sits	“15 to 20 degrees below horizontal eye level”; downward viewing angle “never greater than 60 degrees”	“about 15 degrees (or slightly lower) below the horizontal line”; up to 45° downward is acceptable
Side-to-side offset	“should not be farther than 35 degrees to the left or right”	directly in front for a single primary screen
Tilt	“no more than 10 to 20 degrees”, so the screen is perpendicular to the line of sight	not specified in degrees
Windows	“Place monitor perpendicular to window”	see the CCOHS eye-discomfort sheet below
Bifocal wearers	lower the monitor below the usual recommendation, or raise the chair	placing the top “slightly below eye level” is more comfortable
Sources	OSHA: Monitors	CCOHS: Positioning the Monitor

Two things stand out. First, the numbers are ranges, and CCOHS says explicitly that these are guidelines rather than requirements. Second, none of the variables in the table appears on a monitor’s box. Size, resolution and refresh rate are not in the guidance at all, except for OSHA’s note that “using very large monitors also may increase the angle”, which is a reason to sit further back, not a reason to buy one.

OSHA also lists the zero-cost fixes before any purchase: remove the computer case or other equipment the monitor is sitting on, because that “will raise it too high for all but the tallest users”; raise the chair to lift your line of sight, provided your feet stay supported; and, as a temporary fix, put a book under the front edge to tilt the screen. If the screen is too low rather than too high, the guidance is silent on what to put under it, which is where the stand’s own adjustment range matters.

What a stock stand can do, from the datasheets

Manufacturers publish stand adjustability on their datasheets, and the range varies a lot between models in the same product line. Two current Dell 24-inch monitors illustrate the spread. Both datasheets were read on September 23, 2026.

Specification	Dell SE2425HM (budget line)	Dell UltraSharp U2424H
Stand adjustability	Tilt -5° to +21° only	Height adjustable (150 mm max), tilt -5° to 21°, swivel -45° to 45°, pivot -90° to 90°
Height with stand	412.26 mm (16.23 in.), fixed	364.00 mm to 496.53 mm (14.33 in. to 19.55 in.)
Panel-only weight, for VESA mounting	2.80 kg (6.17 lb)	3.52 kg (7.76 lb)
VESA pattern	100 mm x 100 mm	100 mm x 100 mm
Sources	SE2425HM / SE2725HM datasheet (PDF)	U2424H datasheet (PDF)

The budget stand has no height adjustment at all. If its fixed height puts the top of the screen above your eye level, the only free option is raising the chair; if it puts the screen too low, there is no free option except a stack of something underneath, which OSHA does not recommend for anything other than tilt. The UltraSharp stand offers 150 mm of travel, which covers a lot of seated eye heights but not all of them, and its distance from you is fixed by where the base sits on the desk.

Neither datasheet says anything about how far forward the base has to be. That is the other variable. A stand’s footprint sits on the desk surface, so the screen is as close as the footprint allows, and OSHA’s minimum of 20 inches assumes there is desk depth to spare. An arm clamps to the back edge and holds the screen over the desk, so the distance becomes adjustable in the same way height does.

What a desk-mounted arm adds, from the spec sheets

The two arms below were chosen because both manufacturers publish full specification sheets, not because they are recommendations. Specifications were read on September 23, 2026. Ergotron’s sheet is dated August 9, 2024 and does not list a price; Kensington’s product page shows a price but also marks the product as no longer available, so treat that row as a description of a design rather than a current purchase option.

Specification	Ergotron LX Desk Monitor Arm (45-241)	Kensington SmartFit One-Touch Single Monitor Arm
Monitor weight supported	7 to 25 lb (3.2 to 11.3 kg)	up to 19.8 lb (9 kg); no minimum stated
Typical screen size	up to 34 in., “may be exceeded as long as screen weight does not exceed maximum weight capacity”	13 in. to 34 in., flat or curved
Height range	13 in. (33 cm) lift	6.7 in. to 19.9 in. (170 mm to 505 mm)
Reach	extension up to 25 in. (64 cm)	not stated on the page
Tilt	75° total: 70° up, 5° down	±90°
Pan and rotation	360° each	±90° swivel and rotation
VESA pattern	VESA FDMI MIS-D, 100/75, C (100 x 100 mm and 75 x 75 mm)	75 mm or 100 mm plate
Desk attachment	Two-piece clamp and grommet mount included; low-profile clamp variant fits 0.98 in. to 1.38 in. (25 mm to 35 mm) surfaces	C-clamp for 10 mm to 85 mm surfaces; grommet for 10 mm to 80 mm surfaces and 10.5 mm to 50 mm holes
Warranty	10 years	2 years
Price	not listed on the spec sheet	$114.99 on the product page, marked no longer available
Sources	Ergotron LX spec sheet (PDF)	Kensington product page

Set the two tables side by side and the practical difference is plain. The UltraSharp’s stand travels 150 mm; the Ergotron arm travels 330 mm and adds up to 640 mm of reach, which is what lets you meet both the height row and the distance row of the guidance table at the same time. The budget monitor’s stand travels 0 mm. That is the whole case for an arm, and it is a geometric case, not a comfort claim.

The Ergotron sheet also carries a line worth quoting because it applies to every product in this category: “Ergotron devices are not intended to cure, treat, mitigate or prevent any disease.” If persistent neck or back pain is the reason you are reading, keep the equipment decision separate from getting the pain assessed. A mount changes where the screen is; it does not diagnose anything.

Compatibility checks before buying

An arm that does not fit the monitor or the desk is worse than a stand, because it goes back in the box. These checks come straight from the specification rows above.

1. VESA pattern. The mounting standard is the VESA Flat Display Mounting Interface (FDMI). The MIS-D class covers the 75 x 75 mm and 100 x 100 mm four-hole patterns with M4 screws that most computer monitors use (Wikipedia summary; the standard itself is a paid download from VESA). Both Dell datasheets above list 100 x 100 mm. Check your own monitor’s datasheet, and check whether the holes are behind a cover, as Dell notes for the U2424H.
2. Panel-only weight against the arm’s range, including the minimum. Datasheets list the panel weight without the stand for exactly this purpose. The SE2425HM’s 2.80 kg is below the Ergotron LX’s stated minimum of 3.2 kg, so a light budget monitor on a gas-spring arm rated for heavier screens may not hold position. This is the check most often skipped. Kensington states no minimum, which is not the same as stating that any weight works.
3. Desk thickness and edge. The Kensington clamp accepts 10 mm to 85 mm; Ergotron’s low-profile clamp variant accepts 25 mm to 35 mm, with other kits for thinner surfaces. Measure the desk edge, and check that the underside is flat where the clamp will sit. A desk with a lip, a rear cable tray, or a wall directly behind it may need the grommet option instead.
4. Reach versus desk depth. Ergotron’s extension of up to 25 in. only helps if there is room to fold the arm back. A shallow desk against a wall may leave the screen closer than 20 in. even with an arm.
5. Screen size ceiling. Both arms say 34 in., and Ergotron says the size may be exceeded if the weight is within range. An ultrawide can be within the weight limit and still swing into the wall or the other monitor.
6. Cable length. Lifting a screen 13 in. and pulling it forward 25 in. uses cable. Check that the display cable and power lead reach the new position with slack.

A measuring procedure

This is an editorial proposal for finding out whether you have a position problem before you decide how to solve it. It is not a validated ergonomic assessment. It needs a tape measure and someone to hold it, or a phone photo taken from the side.

Step	What to measure	Compare against
1	Sit as you normally work, feet supported. Measure from the floor to your eyes.	Nothing yet; this is your reference.
2	Measure from the floor to the top of the screen’s visible area.	OSHA and CCOHS: top of screen at or slightly below eye level. A top edge above step 1 is the case OSHA calls “too high”.
3	Measure from your eyes to the screen surface.	OSHA 20 to 40 in.; CCOHS 40 to 74 cm.
4	Sit square to the desk and note where the screen centre is relative to your nose.	OSHA: no more than 35° off to either side.
5	Note where windows and ceiling lights are relative to the screen.	OSHA: screen perpendicular to the window. CCOHS: blinds on windows, task lamp on the document and not the monitor.

If steps 2 and 3 are already within range on the stock stand, an arm buys you flexibility, not a fix. If step 2 is out of range and the stand has height travel, use it. If the stand has no travel, that is the concrete reason to price an arm. If step 5 is the problem, the fix is to turn the desk or add blinds, which the CCOHS eye-discomfort sheet covers and which no mount addresses. That sheet, revised May 1, 2018, also notes that the usual office lighting level of 300 to 500 lux “is not a must” when a task lamp is in use, which is the reason a lamp that lights your paperwork rather than your screen belongs in the same conversation (CCOHS: Eye Discomfort in the Office).

A spend order to test, not a finding

The table below is a proposed order for anyone starting a desk from scratch, derived from the two guidance documents and the datasheets above. It is a rule to test against your own measurements, and the amounts are illustrative.

Order	Change	Cost	Why it comes here
1	Remove anything the monitor sits on; raise or lower the chair; turn the desk so the window is to the side	£0	Every one of these is in the OSHA or CCOHS guidance and none needs a purchase.
2	Use the stand’s own height and tilt travel, if it has any	£0	A 150 mm range covers many seated heights; a tilt-only stand covers none.
3	Blinds, and a task lamp aimed at documents	tens of pounds	CCOHS lists both as glare controls; a mount cannot do either.
4	Desk-mounted arm, after the six compatibility checks	roughly £100 in the Kensington price band; Ergotron price not published on its sheet	Adds height and distance travel a stand lacks.
5	A different panel	varies	Only once position and glare are fixed, because none of the guidance variables is a panel property.

The same logic that puts position ahead of the panel applies to other desk purchases: a keyboard’s first-week impression is about the property on the box, and the property that decides whether you keep it shows up later. It applies to headphone fit and call checks, where published battery figures do not answer individual fit questions. And if the whole workstation is the question, the trackball trial worksheet is built on the same principle: write down an observable requirement first, then buy against it.

When this does not apply

If the work is colour-critical, the panel is the job and its specification is the purchasing decision; position still matters, but it is not the first question. If you work from a laptop without an external screen, the guidance table above will be out of range on height by construction, because a laptop screen sits at keyboard height, and the relevant purchase is a separate keyboard and a laptop stand or arm, not a monitor arm. And if your monitor is lighter than the arm’s stated minimum, as the Dell budget model is against the Ergotron LX, the right arm is one whose range starts lower, not the one with the longer warranty.