Monitor Size & Viewing Distance Calculator
Enter a screen size, aspect ratio and resolution to see the monitor's real width and height, its pixel density (PPI), the distance at which individual pixels blend together, how much of your view it fills, and whether it fits on your desk at the distance you sit. Everything is plain geometry that runs in your browser. Nothing is stored or sent anywhere.
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How it works
The calculator uses only geometry. It has no monitor database and does not look up any product.
- Width and height. The resolution sets the exact shape (we assume square pixels, which mainstream monitors use). With r = horizontal ÷ vertical pixels: height = diagonal ÷ √(1 + r²), width = height × r. Marketing ratios are rounded: 3440 × 1440 is really 43:18, sold as 21:9, so we use the pixel ratio.
- Pixel density. PPI = √(w² + h²) ÷ diagonal. Pixel pitch is 25.4 mm ÷ PPI.
- Pixel-blend distance. Our assumption is a visual acuity of 1 arcminute (1/60°), the angle used to define 20/20 (6/6) vision. Beyond (1 ÷ PPI) ÷ tan(1/60°) a single pixel subtends less than 1 arcminute, so a person with 20/20 vision can't pick out individual pixels. Many people see better than 20/20, so for them pixels stay visible a bit farther out. This tells you about sharpness, not comfort.
- Pixels per degree. At your distance d: PPD = PPI × 2 × d × tan(0.5°). 60 PPD matches the 1-arcminute assumption.
- Field of view. A flat screen of width w at distance d fills 2 × atan(w ÷ 2d) degrees. To fill a chosen angle θ, sit at w ÷ (2 × tan(θ ÷ 2)).
- Desk fit (estimate). depth needed ≈ distance − eyes behind desk edge + monitor depth. It treats everything as a straight line, ignores screen tilt and curvature, and counts multiple screens as one flat row with no bezels.
Worked example
A hypothetical setup: a 27-inch 16:9 monitor at 2560 × 1440, viewed from 28 in (71.1 cm), on a 30 in (76.2 cm) deep desk. Your eyes sit 4 in (10.2 cm) behind the desk's front edge, and the monitor's spec sheet lists 8 in (20.3 cm) of depth behind the screen with its stand.
- Visible size: 23.5 in (59.8 cm) wide × 13.2 in (33.6 cm) tall, 312 sq in (2010 sq cm).
- Pixel density: 108.8 PPI, pixel pitch 0.233 mm.
- Pixel-blend distance at 1 arcminute: 31.6 in (80.3 cm). At 28 in you sit closer than that (53 pixels per degree), so with 20/20 vision you can just make out pixels.
- Field of view: the screen fills about 46° of your horizontal view. To fill exactly 30° you would sit 43.9 in (111.5 cm) away.
- Desk depth needed: 28 − 4 + 8 = 32.0 in (81.3 cm), on a 30.0 in (76.2 cm) desk: about 2.0 in (5.1 cm) short. A monitor arm on the back edge or pulling the desk off the wall could cover the gap.
- For comparison, a 27-inch 3840 × 2160 (4K) screen has 163.2 PPI, and its pixels blend at 21.1 in (53.5 cm).
Our opinion: in a setup like this, we'd find more depth first (a monitor arm on the back edge, or pulling the desk off the wall) so you can sit about 4 in farther back. That would put you past the pixel-blend distance and still inside OSHA's 20–40 in range. If text then looks small, raise your font scaling, as CCOHS suggests, before paying for a sharper monitor.
Monitor dimensions and PPI reference table
Visible screen area for common sizes and resolutions, calculated with the formulas above. A monitor's outer size is bigger because of bezels and the stand.
| Size | Resolution (ratio) | Visible width × height | PPI | Pixel-blend distance |
|---|---|---|---|---|
| 24″ | 1920 × 1080 (16:9) | 20.9 × 11.8 in (53.1 × 29.9 cm) | 91.8 | 37.5 in (95.1 cm) |
| 24″ | 2560 × 1440 (16:9) | 20.9 × 11.8 in (53.1 × 29.9 cm) | 122.4 | 28.1 in (71.3 cm) |
| 24″ | 1920 × 1200 (8:5) | 20.4 × 12.7 in (51.7 × 32.3 cm) | 94.3 | 36.4 in (92.6 cm) |
| 27″ | 1920 × 1080 (16:9) | 23.5 × 13.2 in (59.8 × 33.6 cm) | 81.6 | 42.1 in (107.0 cm) |
| 27″ | 2560 × 1440 (16:9) | 23.5 × 13.2 in (59.8 × 33.6 cm) | 108.8 | 31.6 in (80.3 cm) |
| 27″ | 3840 × 2160 (16:9) | 23.5 × 13.2 in (59.8 × 33.6 cm) | 163.2 | 21.1 in (53.5 cm) |
| 27″ | 5120 × 2880 (16:9) | 23.5 × 13.2 in (59.8 × 33.6 cm) | 217.6 | 15.8 in (40.1 cm) |
| 32″ | 2560 × 1440 (16:9) | 27.9 × 15.7 in (70.8 × 39.8 cm) | 91.8 | 37.5 in (95.1 cm) |
| 32″ | 3840 × 2160 (16:9) | 27.9 × 15.7 in (70.8 × 39.8 cm) | 137.7 | 25.0 in (63.4 cm) |
| 34″ | 3440 × 1440 (43:18) | 31.4 × 13.1 in (79.7 × 33.3 cm) | 109.7 | 31.3 in (79.6 cm) |
| 38″ | 3840 × 1600 (12:5) | 35.1 × 14.6 in (89.1 × 37.1 cm) | 109.5 | 31.4 in (79.8 cm) |
| 49″ | 5120 × 1440 (32:9) | 47.2 × 13.3 in (119.8 × 33.7 cm) | 108.5 | 31.7 in (80.4 cm) |
| 13.5″ | 2256 × 1504 (3:2) | 11.2 × 7.5 in (28.5 × 19.0 cm) | 200.8 | 17.1 in (43.5 cm) |
| 16″ | 2560 × 1600 (8:5) | 13.6 × 8.5 in (34.5 × 21.5 cm) | 188.7 | 18.2 in (46.3 cm) |
Pixel-blend distance assumes 1-arcminute (20/20) acuity. Ratios are exact pixel ratios: 43:18, 12:5 and 64:27 are all sold as "21:9".
What published ergonomic guidance says about distance
These are short quotes and summaries of public sources. Follow the links for full context.
OSHA computer workstations eTool (U.S.)
"Put monitor directly in front of you and at least 20 inches away."
"Generally, the preferred viewing distance is between 20 and 40 inches (50 and 100 cm) from the eye to the front surface of the computer screen."
OSHA also says monitors should not be farther than 35 degrees to the left or right, and the top of the monitor should be at or slightly below eye level. If the desk is too shallow, it suggests pulling the desk away from the wall, putting the monitor in a corner (corners often give more depth), or moving back and adding an adjustable keyboard tray. Source: OSHA eTools: Computer Workstations – Monitors.
CCOHS: Positioning the Monitor (Canada)
"Generally speaking, an arm’s length is usually a good estimation of how far the monitor should be positioned, with adjustments made based on the operator’s characteristics and preferences."
CCOHS notes that published distance guidelines differ, sometimes a lot, and should be treated as starting points. For wide monitors it says it may be necessary to move the monitor farther away so you don't turn your neck as much. If you can't read the screen clearly at the recommended distance, it says it is better to increase the font size than to sit closer. For multiple monitors used equally, it suggests placing them edge to edge in a semi-circle. Source: CCOHS OSH Answers: Office Ergonomics – Positioning the Monitor.
Visual acuity (the 1-arcminute assumption)
20/20 (6/6) vision is defined as resolving detail separated by one minute of arc, which corresponds to 60 pixels per degree. Healthy young eyes often do better than that. Source: Wikipedia: Visual acuity.
This page gives general information, not medical or vision advice. If you have eye strain or pain that doesn't go away, see a qualified eye-care or health professional.
Monitor arms and stands for your screen count
CompareMyDesk doesn't review monitors, but we do review the arms and stands that hold them. An arm lets you push the screen back toward the wall, which can free desk depth and makes it easy to fine-tune distance and height. Before you buy, check the arm's weight and VESA spec against your monitor.
One screen
- Amazon Basics Single Monitor Arm Best Budget Read our review
- Ergotron LX Monitor Arm Best Overall Read our review
- Search single monitor arms on Amazon
Two screens
- HUANUO Dual Monitor Arm Best Value Read our review
- Fenge Dual Monitor Stand Best Overall (a monitor riser stand rather than an arm; badge is from our desk organizers reviews) Read our review
- Search dual monitor arms on Amazon
Three screens
- VIVO Triple Monitor Mount Best for Multi-Monitor Read our review
- Search triple monitor mounts on Amazon
Named products are picks from CompareMyDesk's own reviews. Search links go to Amazon results so you can compare current options yourself. Check the arm's weight and VESA spec against your monitor.
As an Amazon Associate, CompareMyDesk earns from qualifying purchases.
Planning the rest of your desk? Try the free Desk Setup Planner for approximate ergonomic heights and a gear checklist, or browse all reviews on CompareMyDesk.com.
FAQ
How far should I sit from my monitor?
OSHA's computer workstations eTool says to put the monitor at least 20 inches away and describes 20 to 40 inches (50 to 100 cm) from your eyes to the screen as the generally preferred viewing distance. CCOHS says an arm's length is usually a good estimate, adjusted to the person. If text looks too small at that distance, CCOHS says it is better to increase the font size than to sit closer.
At what distance can I no longer see individual pixels?
Assuming 20/20 vision (1 arcminute of acuity), divide about 3438 by the PPI to get the distance in inches. A 27-inch 2560 × 1440 monitor (108.8 PPI) reaches that point at about 31.6 in (80.3 cm). People with sharper vision will still see pixels a little farther out.
Is a 27-inch 4K monitor sharper than a 27-inch 1440p monitor?
Yes. It has 163.2 PPI against 108.8 PPI, so its pixels blend at about 21.1 in (53.5 cm) instead of 31.6 in (80.3 cm). Our opinion: the difference matters most if you sit closer than the 1440p blend distance and read a lot of small text.
Will a monitor fit on my desk?
As a rough estimate, take your viewing distance, subtract how far your eyes sit behind the desk's front edge, and add the monitor's depth behind the screen. In the worked example above that comes to 32.0 in (81.3 cm). It is a straight-line estimate that ignores tilt and curved screens.
Does this calculator use real monitor specifications?
No. It uses only the size and resolution you enter plus standard geometry. Check the manufacturer's spec sheet for the outer dimensions, stand depth and weight of a specific monitor.