# What TV size is right for my room?

Recommends a TV screen size for your viewing distance from the SMPTE 30° and THX 40° viewing angles, and shows the viewing angle of a TV you already have in mind.

- Page: https://www.acalculator.org/everyday-life/tv-size-calculator
- JSON spec: https://www.acalculator.org/everyday-life/tv-size-calculator.json
- Version: 9d8d35ce8396

## Default answer

Example with the default inputs (Viewing distance 8 ft): At 8 ft, a TV of 59 in fills 30° of your view; 80.2 in fills 40°.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| d | Viewing distance | From your eyes, where you sit, to the screen. |
| tv | A TV you are looking at | Optional: the diagonal of a 16:9 TV, to see the viewing angle it gives. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| smpte | Smallest size (SMPTE, 30°) | The 16:9 screen that fills a 30° viewing angle. |
| thx | Cinema size (THX, 40°) | The 16:9 screen that fills a 40° viewing angle. |
| smpteWidth | SMPTE screen width | 2 × distance × tan 15°. |
| angle | Your TV’s viewing angle | 2 × arctan(width ÷ (2 × distance)), in degrees. |
| verdict | Your TV | Below 30°, from 30° to 40°, or above 40°. |

## Method

Screen width = 2 × distance × tan(angle ÷ 2), at 30° (SMPTE) and 40° (THX); diagonal = width × √(16² + 9²) ÷ 16.

## Assumptions

- The TV is 16:9, as almost all TVs are, and you sit straight in front of the screen.
- The size is the diagonal of the visible picture, as TVs are sold.
- SMPTE’s 30° is a smallest comfortable size for a room; THX’s 40° is a cinema-like size.

## Worked examples

1. d = 2.4384 gives smpte = 1.499279, thx = 2.036553. Source: Optimum HDTV viewing distance, Wikipedia (SMPTE: the screen should fill at least a 30° field of view; THX: about 40°), https://en.wikipedia.org/wiki/Optimum_HDTV_viewing_distance (retrieved 2026-10-03).
2. d = 3, tv = 1.651 gives smpte = 1.844585, angle = 26.972888, verdict = Smaller than SMPTE’s 30°: a bigger TV or a closer seat fills more of your view. Source: Optimum HDTV viewing distance, Wikipedia (SMPTE: the screen should fill at least a 30° field of view; THX: about 40°), https://en.wikipedia.org/wiki/Optimum_HDTV_viewing_distance (retrieved 2026-10-03).

## FAQ

### What size TV should I get for 8 feet?

At 8 ft (96 in), a 59 in TV fills 30° of your view (SMPTE) and an 80 in TV fills 40° (THX). A 65 in or 75 in TV sits between the two.

### What are the SMPTE and THX recommendations?

SMPTE, the film and television engineers’ society, recommends that the screen fills at least a 30° field of view. THX, which certifies cinemas and home theaters, recommends about 40° for an immersive picture.

### How is the TV size worked out from the angle?

A screen that fills an angle θ at distance d is 2 × d × tan(θ ÷ 2) wide. A 16:9 screen’s diagonal is its width × √(16² + 9²) ÷ 16, about 1.147 times the width.

### How far should I sit from a 65 inch TV?

A 65 in TV is 56.7 in wide. It fills 40° at 56.7 ÷ (2 × tan 20°) = 77.8 in (6.5 ft) and 30° at 56.7 ÷ (2 × tan 15°) = 105.7 in (8.8 ft).

### Does 4K let me sit closer?

Yes. A sharper picture lets you sit closer before you see the pixels, so a 4K TV can fill the larger THX angle without looking soft. The angles here are about comfort and immersion, not resolution.

### Where do I measure the distance from?

From your eyes, where you usually sit, to the screen.

## Sources

- Optimum HDTV viewing distance, Wikipedia (SMPTE recommends that the screen fills at least a 30° field of view; THX recommends about 40°). https://en.wikipedia.org/wiki/Optimum_HDTV_viewing_distance (retrieved 2026-10-03)