Cables and desk layout

How Should You Arrange Two Monitors So You Aren't Turning Your Head All Day?

Published · By Ergocrew · Specs and guidance as of that date, from the pages under Sources

Summary

It depends on whether one screen does most of the work. If it does, that one goes straight in front of you and the second sits beside it for glances. If you use both about equally, the join between them goes in front of you and each screen angles in slightly. With two 24-inch screens at 25 inches from your eyes, the middle of each screen in an equal pair is about 23 degrees to the side, while a side screen in the main-plus-second layout is about 40 degrees.

The two layouts

OSHA's evaluation checklist describes both: "the position of the primary monitor is directly in front of the user and the other monitors are directly beside it. If time is split evenly between monitors, they are next to each other within a comfortable viewing angle with minimal head movement." CCOHS, the Canadian occupational safety centre, sets out the same pair in its monitor guidance, with an equal-use pair touching at the edges in a semicircle around you.

How do you know which one you are? For a day, notice where your eyes go. A code editor on one screen and documentation on the other, switched between every few minutes, is equal use. A design app on one screen and email on the other is main-plus-second.

Working out the angles

CCOHS gives the figures to aim for: "The side to side optimum viewing is directly in front of you, with 15° to either side. 35° side to side is the maximum."

A 24-inch monitor with a 16:9 screen is about 20.9 inches wide. With the screens placed edge to edge, that lets you work out how far your eyes and head turn to reach the middle of each screen, at the distances OSHA's monitor page allows (20 to 40 inches).

Eye-to-screen distanceEqual pair, middle of each screenMain plus second, middle of the second screen
20 inchesabout 28°about 46°
25 inchesabout 23°about 40°
30 inchesabout 19°about 35°
40 inchesabout 15°about 28°

Two things come out of the table. In an equal pair, each screen's middle stays inside CCOHS's 35-degree limit at every distance, so both screens are usable without moving the chair. In the main-plus-second layout, the second screen's middle is past 35 degrees until you sit about 30 inches back. A screen you only glance at can sit there. For a long stretch of work on it, turning the chair brings it back in front of you. With 27-inch monitors, which are about 23.5 inches wide, every angle in the table gets a few degrees larger.

Stands and arms come after the layout

Once you know where the screens need to be, choose stands or arms that can hold them there. A dual arm on one base is quicker to fit, and two single arms let each screen move on its own. Our guide to single and dual monitor arms goes through that choice.

The computer has to support two

Two video ports on a dock don't guarantee two screens. Apple says the number of external displays "depends on your Mac model and the resolution and refresh rate of each display," and that a hub or daisy chain "does not increase the maximum number of displays that you can connect." The MacBook Air with M2 supports one external display. The MacBook Air with M4 supports "up to two external displays simultaneously in addition to the built-in display."

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Related guides

Sources

  1. OSHA Computer Workstations eTool, Evaluation Checklist
  2. OSHA Computer Workstations eTool, Monitors
  3. CCOHS, Working in a Sitting Position - Basic Requirements
  4. CCOHS, Office Ergonomics - Positioning the Monitor
  5. Apple, How many displays can be connected to MacBook Air
  6. Apple, MacBook Air (M2, 2022) Tech Specs

We have not tested these products. Specs and guidance are as published on these pages on the date above and can change; the manufacturer's page for your model has the current details.

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