TV Size and Viewing Distance Calculator
Find the best viewing distance for a TV size, or the right TV size for your sofa distance, using SMPTE 30°, THX 40° and the visual-acuity limit for 1080p, 4K and 8K.
Angles follow SMPTE EG-18 (30° field of view) and THX (about 40°); they are comfort guidelines, not rules.
| Size | Width (in) | THX 40° | SMPTE 30° | Pixels just invisible at |
|---|---|---|---|---|
| 43" | 37.5 | 4.29 | 5.83 | 2.8 |
| 48" | 41.8 | 4.79 | 6.51 | 3.12 |
| 50" | 43.6 | 4.99 | 6.78 | 3.25 |
| 55" | 47.9 | 5.49 | 7.45 | 3.58 |
| 65" | 56.7 | 6.49 | 8.81 | 4.23 |
| 75" | 65.4 | 7.48 | 10.16 | 4.88 |
| 77" | 67.1 | 7.68 | 10.44 | 5.01 |
| 83" | 72.3 | 8.28 | 11.25 | 5.4 |
| 85" | 74.1 | 8.48 | 11.52 | 5.53 |
| 98" | 85.4 | 9.78 | 13.28 | 6.37 |
How far should you sit from a 65-inch TV, and how big a TV suits an 8-foot sofa distance? This calculator answers both with the three yardsticks home-cinema people use: the SMPTE 30° viewing angle, the more immersive THX 40° angle, and the distance at which 20/20 vision stops seeing individual pixels for 1080p, 4K or 8K. A table repeats the numbers for sizes from 43 to 98 inches.
How to use this tool
- Choose whether you know the TV size or your seating distance.
- Enter the diagonal (inches or cm) or the distance from your eyes to the screen (feet or metres).
- Pick the resolution and, for unusual screens, the aspect ratio.
- Compare the THX and SMPTE figures and check the table for neighbouring sizes.
Formula
width W = d × 16 / √337 (16:9) · THX distance = W ÷ (2 tan 20°) ≈ 1.37 W · SMPTE distance = W ÷ (2 tan 15°) ≈ 1.87 W · pixel limit = (W ÷ horizontal pixels) ÷ tan(1′)
d is the diagonal; √337 is the diagonal of a 16 × 9 rectangle. One arc-minute (1/60°) is the detail 20/20 vision resolves, so at the pixel limit each pixel just fills that angle; tan(1′) ≈ 0.000291.
Example
A 65-inch 16:9 TV is 56.65 in wide. THX: 56.65 ÷ (2 × tan 20°) = 77.8 in ≈ 6.5 ft (1.98 m). SMPTE: 56.65 ÷ (2 × tan 15°) = 105.7 in ≈ 8.8 ft (2.69 m). For 4K, each pixel is 0.0148 in wide, so pixels disappear beyond about 50.7 in (4.2 ft). From 8 ft away, the THX angle calls for about an 80-inch screen.
Frequently asked questions
Which distance should I use?
SMPTE 30° suits mixed TV watching; THX 40° fills more of your view for films and games. Anywhere between the two is comfortable for most people.
Is 4K worth it at my distance?
If you sit closer than about 1.8 screen-widths (1 ÷ (1920 × tan 1′)), 1080p pixels become visible and 4K is a clear improvement. 8K only adds visible detail closer than about 0.9 screen-widths, where 4K pixels start to show — very close for a TV.
Do I measure to the wall or the screen?
From your eyes to the screen surface while seated.
Last updated:
Page address with these inputs: https://kakao.mobile/tools/tv-size-viewing-distance-calculator/
Cite or embed this tool
kakaoCalc. (2026, November 8). TV Size and Viewing Distance Calculator. https://kakao.mobile/tools/tv-size-viewing-distance-calculator/
“TV Size and Viewing Distance Calculator.” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/tv-size-viewing-distance-calculator/.
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