TV Size Calculator
Enter the TV's diagonal in inches or cm to see the screen's width and height and the recommended viewing distances.
TV parameters
Resolution
Screen diagonal length
Viewing parameters
Optimal distance (THX 40°)
Minimal distance (pixels invisible)
How Is the Ideal TV Size Calculated Based on Viewing Distance?
The right TV size depends on how far you sit and the resolution of what you watch. The calculation uses two international standards: THX and SMPTE.
Viewing Distance Standards
The screen fills 40° of your horizontal field of view. Recommended for a cinema-like, immersive picture. Distance ≈ screen width × 1.37.
You can see the whole screen with your eyes fixed at the centre. Suits large rooms and several viewers. Distance ≈ screen width × 1.87.
Effect of 4K (UHD) vs 1080p (FHD) Resolution on Viewing Distance
Resolution sets the shortest distance at which you can make out individual pixels. A 4K screen has four times the pixel density of 1080p, so pixels disappear at a much closer distance. For the same screen size, the minimum viewing distance is much shorter.
| Screen | Min. 1080p | Min. 4K | 4K advantage |
|---|---|---|---|
| 43" | ~1.07 m | ~0.54 m | Noticeable up close |
| 55" | ~1.37 m | ~0.68 m | Noticeable under 2 m |
| 65" | ~1.62 m | ~0.81 m | Noticeable under 2.5 m |
| 75" | ~1.87 m | ~0.93 m | Noticeable under 3 m |
What Is the Difference Between Inches and Screen (cm) Dimensions?
A TV's "size" is its diagonal length in inches, an industry standard that comes from the US. The diagonal runs from the bottom-left to the top-right corner of the screen and does not include the bezel (frame).
For a 16:9 screen, the actual dimensions are: Width (cm) = Diagonal (cm) × 0.872 and Height (cm) = Diagonal (cm) × 0.490. Example: a 55" (139.7 cm) TV is 139.7 × 0.872 ≈ 121.7 cm wide and 139.7 × 0.490 ≈ 68.5 cm tall.
When buying, note that the dimensions on the box (width × height × depth) include the bezel, so they are 2–5 cm larger than the diagonal-based figures.
Room Standards to Consider When Buying a TV
The TV's centre should be at eye level or 5–10 cm below. Mounting too high causes neck strain.
The recommended viewing distance should be at least 60% of the room's depth. A 55" or 65" screen suits a 3 m deep room.
Bright windows create screen glare. Choose a matte panel or anti-reflective coating; lower brightness in dark rooms.
If seats view the TV from more than 30° to the side, choose an OLED or IPS panel; VA and TN panels show colour shift at wide angles.
Leave at least 5–10 cm of air circulation space behind a wall-mounted TV; overheating shortens panel life.
Popular TV Sizes: Quick Reference
| Size | W × H | THX dist. | SMPTE dist. | Min. (4K) |
|---|---|---|---|---|
| 43" | 95 × 54 cm | ~1.31 m | ~1.78 m | ~0.54 m |
| 50" | 111 × 62 cm | ~1.52 m | ~2.07 m | ~0.62 m |
| 55" | 122 × 68 cm | ~1.67 m | ~2.27 m | ~0.68 m |
| 65" | 144 × 81 cm | ~1.98 m | ~2.69 m | ~0.81 m |
| 75" | 166 × 93 cm | ~2.28 m | ~3.10 m | ~0.93 m |
| 85" | 188 × 106 cm | ~2.59 m | ~3.51 m | ~1.06 m |