ZcaccScreen Width Calculator

Screen Width Calculator

Screens are sold by their diagonal, but what matters on a desk or a wall is how wide and tall they are. Enter the diagonal and aspect ratio to get the real width and height, then compare two screens drawn to scale or work out whether a multi-monitor setup will fit.

Screen width calculator

Screen and Monitor Planning Pack

Excel screen size calculator for any diagonal and ratio, printable screen size tables for monitors and TVs, a desk and wall layout planner and a monitor buying comparison sheet.

Formats: XLSX, PDF, DOCX. Instant download after payment (link valid 72 hours, up to 5 downloads). AI-assisted: the templates were drafted with AI help and reviewed and laid out before publishing.

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Free sample: Desk Layout Planner (PDF, 58 KB)

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The formula

For a screen with diagonal d and aspect ratio w:h, width = d × w ÷ √(w² + h²) and height = d × h ÷ √(w² + h²). For 16:9, √(16² + 9²) ≈ 18.36, so the width is about 0.872 × the diagonal and the height about 0.490 × the diagonal. Pixel density (PPI) is the diagonal in pixels, √(horizontal² + vertical²), divided by the diagonal in inches.

Common screen sizes

ScreenWidthHeight
13.3″ 16:1011.3 in (28.6 cm)7.0 in (17.9 cm)
14″ 16:1011.9 in (30.2 cm)7.4 in (18.8 cm)
15.6″ 16:913.6 in (34.5 cm)7.6 in (19.4 cm)
24″ 16:920.9 in (53.1 cm)11.8 in (29.9 cm)
27″ 16:923.5 in (59.8 cm)13.2 in (33.6 cm)
32″ 16:927.9 in (70.8 cm)15.7 in (39.8 cm)
34″ 21:931.3 in (79.6 cm)13.2 in (33.6 cm)
49″ 32:947.2 in (119.8 cm)13.3 in (33.7 cm)
55″ 16:947.9 in (121.8 cm)27.0 in (68.5 cm)
65″ 16:956.7 in (143.9 cm)31.9 in (80.9 cm)
75″ 16:965.4 in (166.0 cm)36.8 in (93.4 cm)

These are the visible screen areas; the outside dimensions add the bezel and, for TVs, the stand.

Worked example

Someone deciding between two 27-inch 16:9 monitors and one 34-inch ultrawide measures a 48-inch-wide desk shelf. Each 27-inch screen is 23.5 in wide, so with 7 mm bezels two side by side are about 48.2 in — too wide for the shelf. The 34-inch ultrawide (marketed as 21:9; 3440 × 1440 panels are exactly 43:18, very close to the 64:27 used here) is 31.3 in wide and 13.2 in tall — almost exactly the same height as a 27-inch 16:9 screen (13.2 in), so it feels like a 27-inch monitor with extra width. At 3440 × 1440 it has about 110 PPI, close to a 27-inch 1440p monitor’s 109 PPI.

Aspect ratios explained

RatioWhere you see itWidth ÷ height
16:9TVs, most monitors, laptops1.78
16:10Many laptops and productivity monitors1.60
21:9 (64:27)Ultrawide monitors and cinema-style content2.37
32:9Super-ultrawide (like two 16:9 side by side)3.56
4:3Older monitors, iPad-style tablets1.33
3:2Some laptops and tablets1.50

Comparing diagonals across different ratios is misleading: a wider screen has a smaller height for the same diagonal.

Pixel density and viewing distance

Higher PPI makes text sharper, but only up to the point where your eyes can no longer see individual pixels. Using the common rule of about one arcminute of visual acuity, the calculator estimates the distance at which pixels blend together. A 27-inch 4K monitor (163 PPI) reaches that at about 1.8 feet, while a 27-inch 1080p monitor (82 PPI) needs about 3.5 feet. Operating-system scaling adjusts text size so a high-PPI screen still has readable text.

Screen size and viewing distance

UseTypical distanceSize that often suits
Laptop18–24 in13–16 in
Desk monitor20–30 in24–27 in (16:9) or 34 in ultrawide
Large desk monitor30–36 in32 in 4K
Living-room TV6–9 ft55–75 in
Projector screen10–14 ft100–120 in

These are common starting points rather than rules — personal preference, room layout and resolution all matter. A higher-resolution screen can be larger or closer without visible pixels.

Portrait and vertical setups

Rotating a monitor to portrait swaps its width and height: a 27-inch 16:9 screen becomes about 13.2 inches wide and 23.5 inches tall — handy for code, documents and reading. Choose “9:16 (portrait)” in the calculator to see the size, and check that the stand or arm supports rotation.

Tips for planning a desk or wall

Privacy

All calculations run in your browser.

Frequently asked questions

How wide is a 27-inch monitor?

About 23.5 inches (59.8 cm) of screen for 16:9, plus the bezel.

How do I calculate screen width from the diagonal?

Width = diagonal × ratio width ÷ √(ratio width² + ratio height²).

What is PPI?

Pixels per inch — the diagonal resolution in pixels divided by the diagonal in inches.

Is a 34-inch ultrawide taller than a 27-inch monitor?

About the same height; it’s mainly wider.

Why is 21:9 sometimes 64:27?

Ultrawide 3440 × 1440 and 2560 × 1080 panels are exactly 43:18 and 64:27, marketed as 21:9.

Does the diagonal include the bezel?

No, it measures the visible screen only.

How wide are two 24-inch monitors side by side?

About 41.8 inches of screen (2 × 20.9 in), plus bezels.

What PPI is considered sharp?

Around 100–110 PPI is typical for desk monitors; 140 and above looks crisp at normal distance, especially with scaling.