Viewing distance, field of view and room fit
TV Size Calculator
Calculate a TV diagonal from viewing distance and horizontal field of view, find the matching seating distance, measure your current field of view, or compare two 16:9 or custom screens.
TV size and viewing-distance formulas
For viewing distance D and horizontal field of view θ, screen width = 2 × D × tan(θ ÷ 2). For aspect ratio a:b, height = width × b ÷ a and diagonal = √(width² + height²).
If diagonal is known, the calculator first finds screen width, then uses viewing distance = width ÷ (2 × tan(θ ÷ 2)). Actual horizontal field of view is 2 × atan(width ÷ (2 × distance)).
Choose the angle deliberately. There is no single correct viewing angle for every person, room, resolution or type of content. This tool models the geometry of the angle you enter; it does not prescribe a medical, safety or purchasing standard.
Checked examples
| Mode | Inputs | Checked result |
|---|---|---|
| TV size | 10 ft, 30°, 16:9 | 73.783 in diagonal; 64.308 × 36.173 in |
| Viewing distance | 65 in, 30°, 16:9 | 8.809 ft (2.685 m) |
| Actual field of view | 65 in at 10 ft, 16:9 | 26.563° horizontal |
| Compare | 55 vs 75 in at 10 ft, 16:9 | 22.591° vs 30.472°; 85.95% more screen area |
How to use the result
- Measure from the screen plane to the usual eye position, not to the front of the sofa.
- TV sizes are nominal viewable diagonals. The stand, bezel and mounting clearances are not included.
- Use the custom aspect-ratio fields for non-16:9 displays. The entered field of view always refers to horizontal screen width.
- A larger diagonal at the same distance increases both field of view and viewable area. It does not by itself determine image sharpness.
- Before buying, verify the manufacturer’s full product dimensions, weight, stand depth, mount pattern, ventilation and cable clearance.
- Distances, diagonals and aspect-ratio values must be finite and positive. Field of view must be between 1° and 120°.