Screen Size Calculator

Calculate TV or monitor dimensions from diagonal size and aspect ratio. Find optimal viewing distance.

By Konstantin Iakovlev · Updated September 2026 · Source: IETF

in
Aspect Ratio

Width

47.9"

Height

27.0"

Area

1,292.6 in²

Screen Dimensions

Width47.94 in (121.8 cm)
Height26.96 in (68.5 cm)
Screen Area1,292.6 in² (8,339 cm²)

Optimal Viewing Distance

Minimum (1.5× diagonal)82.5 in (6.9 ft)
Maximum (2.5× diagonal)137.5 in (11.5 ft)
Recommended Range6.9 – 11.5 ft

Use the Screen Size Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only. Results are estimates based on the information you provide and the assumptions described on this page.

How It Works

Knowing a screen's diagonal alone tells you surprisingly little about how it will sit on a wall or stand. What actually matters for fit is the width and height, and those depend on both the diagonal and the aspect ratio. This tool works out both.

The dimensions come straight out of the Pythagorean theorem. For a diagonal d and an aspect ratio w:h, width and height work out to W = d * (w / sqrt(w^2 + h^2)) and H = d * (h / sqrt(w^2 + h^2)). Viewing distance scales with the diagonal as well: the calculator shows 1.5 to 2.5 times the diagonal, a common rule of thumb, whatever the resolution. Enter the resolution and it also gives pixels per inch: the diagonal in pixels, sqrt(width² + height²), divided by the diagonal in inches.

One trap worth avoiding is treating the active display area as the full size of the set. Bezels add inches the formula never sees, so measure your available space and leave margin before you commit to a model. Bigger is not automatically better, either: a panel that overwhelms a short viewing distance trades immersion for eye strain, and one viewed from too far simply wastes resolution.

Example: Setting up a 75-inch 4K TV

  1. 1 Input a diagonal of 75 inches and the 16:9 aspect ratio, and optionally the 3840 × 2160 resolution.
  2. 2 Width = 75 × 16 / sqrt(16² + 9²) = 75 × 16 / 18.358 = 65.37 in (166.0 cm). Height = 75 × 9 / 18.358 = 36.77 in (93.4 cm). Screen area = 65.37 × 36.77 = 2,403.6 in².
  3. 3 Viewing distance: 1.5 × 75 = 112.5 in (9.4 ft) to 2.5 × 75 = 187.5 in (15.6 ft). Pixel density: sqrt(3840² + 2160²) = 4,405.8 pixels ÷ 75 in = 59 PPI.
  4. 4 The display area is about 65.4 by 36.8 inches; add the bezel and stand from the maker's spec sheet before choosing a wall mount or TV stand.

Source: IETF · Last updated: September 2026

Frequently Asked Questions

What is the best TV size for my room?
A common guideline is that viewing distance should be 1.5 to 2.5 times the diagonal screen size. For a 10-foot (120-inch) viewing distance, that rule gives a diagonal of 120 ÷ 2.5 = 48 inches to 120 ÷ 1.5 = 80 inches.
How do I calculate TV dimensions from diagonal size?
For a 16:9 TV, multiply the diagonal by 0.872 for width and 0.49 for height. A 65-inch TV is about 56.7 inches wide and 31.9 inches tall, not including the stand.
What does aspect ratio mean for screens?
16:9 is the standard widescreen ratio for TVs and most monitors. Ultrawide monitors use 21:9 for extra horizontal space. The aspect ratio determines the shape of the screen, not the size.

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