How the TV viewing distance calculator works
How big a screen looks depends on the angle it fills in your view. SMPTE’s guidance is about 30°, which works out to roughly 1.6 times the screen diagonal. THX’s sizing advice (screen size ≈ seating distance × 0.835) corresponds to about 40°, or roughly 1.2 times the diagonal.
The calculator uses trigonometry on a 16:9 screen to give both distances, your current viewing angle, and the screen sizes that fit your seat. The range bar shows where your seat falls.
Formula and assumptions
- θ
- 30° for the far end of the range, 40° for the near end
Assumptions and limits
- Assumes a 16:9 screen. Ultra-wide screens fill more width at the same diagonal.
- Viewing angle guidance is a comfort guideline, not a rule; resolution, content, and preference matter.
Worked example
A 65 in TV and a couch 8 ft from the screen.
- Screen width = 65 × 0.872 = 56.7 in.
- 40° distance = 28.3 ÷ tan 20° = 77.9 in (6.5 ft).
- 30° distance = 28.3 ÷ tan 15° = 105.7 in (8.8 ft).
- Your seat at 8 ft is inside the 6.5–8.8 ft range.
These are the calculator’s default values, so the live result above matches this example until you change an input.
How to measure correctly
- Measure from where your eyes will be, not the front of the couch.
- Measure to the screen surface, not the wall behind it.
- For several seats, check the closest and farthest.
Seating distance by screen size
| Screen | Closest (40°) | Farthest (30°) |
|---|---|---|
| 43 in | 4.3 ft | 5.8 ft |
| 50 in | 5.0 ft | 6.8 ft |
| 55 in | 5.5 ft | 7.5 ft |
| 65 in | 6.5 ft | 8.8 ft |
| 75 in | 7.5 ft | 10.2 ft |
| 85 in | 8.5 ft | 11.5 ft |
TV Viewing Distance Calculator FAQ
How far should I sit from a 65 inch TV?
About 6.5 to 8.8 ft, from a 40° viewing angle up close to a 30° angle at the far end.
What size TV should I get for my room?
Enter your seating distance. At 8 ft, screens from about 59 to 80 in fall within the 30–40° range; the larger end feels more cinematic.
What is the SMPTE viewing distance?
SMPTE’s guideline is a screen filling about 30° of your field of view, roughly 1.6 times the screen diagonal for a 16:9 TV.
What is the THX recommendation?
THX suggests a screen size of about 0.835 times your seating distance, which corresponds to roughly a 40° viewing angle.
Does 4K let me sit closer?
Higher resolution makes individual pixels harder to see at closer distances, which is one reason larger screens at the 40° end are more comfortable than they used to be.
How high should I mount the TV?
Many guides suggest the center of the screen near seated eye level. This calculator handles distance only.