How high to mount a TV, and how far away to sit: in cm, for your sofa
Mount the TV so the centre of the screen is at your seated eye height: about 100–110 cm from the floor on most sofas, but measure yours. Sit 1.2 to 1.6 times the screen's diagonal away: 1.7–2.3 m for a 55-inch TV (THX 40° to SMPTE 30°). Keep the top edge within 15° of your eye line, as CEDIA recommends.
Type your screen size, how far your seat is from the wall, and your eye height when you sit. The calculator gives the height for the centre of the screen, the distance range for your screen, and the screen size for your distance. Turn on "Above a fireplace" for a chimney breast.
Height: the centre at your eye level
The common rule is simple: the centre of the screen sits at the height of your eyes when you sit. Then you look straight ahead, and the top and bottom edges sit a few degrees above and below your eye line.
Two industry figures set the limit. THX says a viewer should not have to look up more than 15°. CEDIA, the home-cinema trade body, says no viewer should have more than 15° to the top or the bottom of the screen. The calculator uses CEDIA's test, because it is the stricter of the two for a big screen.
The figure most guides give for eye height, about 100–110 cm (around 42 inches), has no authoritative source that we could find. It is a fair average for a standard sofa, but a low, deep sofa can put your eyes under 100 cm, and a firm armchair over 110 cm. So measure: sit as you watch, and have someone measure from the floor to the corner of your eye.
Distance: how far to sit
Two numbers are widely quoted. They both describe how much of your view the screen fills, measured from edge to edge.
- SMPTE, 30°: sit about 1.6 times the diagonal away. It is widely quoted as the SMPTE figure, although Wikipedia notes that SMPTE itself seems to make no direct recommendation.
- THX, 40°: sit about 1.2 times the diagonal away, for a more cinema-like view. THX's own range runs from 40° up close to about 28° at the back.
People in a lab often choose to sit further back than either figure. In one Japanese study of HD screens from 24 to 65 inches, the preferred distance followed a simple formula, which for a 55-inch screen comes to about 2.8 m. It was one study, with its own screens and brightness, so treat it as a sense check, not a rule.
| Screen | Width × height | THX 40° | SMPTE 30° | One study | Bottom edge, centre at 105 cm |
|---|---|---|---|---|---|
| 43 in | 95 × 54 cm | 131 cm | 178 cm | 240 cm | 78 cm |
| 50 in | 111 × 62 cm | 152 cm | 207 cm | 263 cm | 74 cm |
| 55 in | 122 × 68 cm | 167 cm | 227 cm | 280 cm | 71 cm |
| 65 in | 144 × 81 cm | 198 cm | 269 cm | 314 cm | 65 cm |
| 75 in | 166 × 93 cm | 228 cm | 310 cm | – | 58 cm |
| 85 in | 188 × 106 cm | 259 cm | 351 cm | – | 52 cm |
The sizes are for 16:9 screens, measured on the diagonal. The study covered screens up to 65 inches only.
Which size for your room
Turn the rule round to find a size. Measure from where your eyes will be to the wall the screen will hang on, then:
| Seat to screen | SMPTE 30° | THX 40° |
|---|---|---|
| 2.0 m (6 ft 7 in) | 48 in | 66 in |
| 2.5 m (8 ft 2 in) | 60 in | 82 in |
| 3.0 m (9 ft 10 in) | 73 in | 99 in |
| 3.5 m (11 ft 6 in) | 85 in | 115 in |
The THX sizes get very large at living-room distances, so for most rooms the SMPTE column is the realistic one. Measure from roughly where your eyes are when you sit, a little behind the sofa's front edge, not from the back of the sofa.
Above a fireplace or chimney breast
Many UK living rooms have a chimney breast, and the flat wall above the mantel looks like the obvious place for a screen. The catch is height. The screen has to clear the mantel, and its centre ends up far above your eyes.
From a sofa 2.7 m away, that 55-inch screen puts its top edge 19° above your eye line, more than CEDIA's 15°. To bring it within 15°, you would sit about 3.5 m back. One designer's rule is to keep the TV at seated eye height and let the fireplace be the room's main feature.
The usual ways round it:
- Use an alcove. The recesses either side of a chimney breast often take a TV on a low unit, at eye height.
- Sit further back, if the room allows: the calculator tells you how far.
- Choose a smaller screen, so its centre sits lower above the same mantel.
- Use a mount that pulls down in front of the mantel when you watch.
The calculator starts the screen 10 cm above the mantel. That gap is our assumption: a working fire may need more, so check your fire maker's guidance on heat first.
Where the guidance disagrees
| Question | What sources say | We use |
|---|---|---|
| Height | Common rule: centre at eye height. Wikipedia: eyes level with the bottom or the middle of the screen. CEDIA: typically eyes at a third to a sixth of the way up the screen. | Centre at eye height, with CEDIA's 15° as the limit |
| Looking up | THX: no more than 15° up. CEDIA: no more than 15° to the top or the bottom edge. | CEDIA's edge test |
| Distance | SMPTE (as quoted): 30°, 1.6 × diagonal. THX: 40°, 1.2 × diagonal, range to 28°. One study: further back than both. | All three, side by side |
The sofa decides the rest. Place the sofa where it works for the room, then fit the TV to it, not the other way round: small living room layouts, with measurements, shows how. If you are buying a new sofa, check it will go through the door with the sofa fit calculator, and size the rug under it with the rug size calculator.
Try the TV on another wall
Snuug, the iPhone room app, rebuilds your room in 3D from one slow walk round it. You can try the TV on each wall, and the sofa in each spot, before you drill a single hole. Your room comes to within about 3% of its real size in our tests of ten homes, so you can see the TV from your own sofa before you mount it.
Questions
How high should a 55-inch TV be mounted?
With its centre at your seated eye height, usually about 105 cm. A 55-inch screen is about 68 cm tall, so its bottom edge sits about 71 cm from the floor and its top about 139 cm. Measure your own eye height: low sofas can bring it under 100 cm.
How far should I sit from a 65-inch TV?
About 2.0 m (THX's 40°) to 2.7 m (SMPTE's 30°). THX's own range runs out to about 2.9 m. In one lab study, people chose to sit further back, about 3.1 m, from a screen this size.
What size TV for a 3 m viewing distance?
By the SMPTE 30° figure, about 73 inches; by THX's 40°, about 99 inches. A 65-inch screen at 3 m fills about 27° of your view, a little less than either.
Can I mount a TV above a fireplace?
You can, but the screen ends up high. A 55-inch TV 10 cm above a 120 cm mantel has its centre about 164 cm up, and from 2.7 m you look up 19° to the top edge, more than CEDIA's 15°. You would need to sit about 3.5 m back. A stand in the alcove beside the chimney breast keeps the screen at eye level. Check your fire maker's guidance on heat.
How high should a TV be in a bedroom?
Measure your eye height where you actually watch, for example sitting up against the headboard, and use it in the calculator. If you watch lying down, a bracket that tilts the screen down helps keep the angle within 15°.
How do I measure my seated eye height?
Sit as you usually do on the sofa, and ask someone to measure from the floor to the corner of your eye. Guides usually quote 100–110 cm for a standard sofa, but a low, deep sofa can bring it under 100 cm.
Editorial notes
Written by the Snuug team and checked on 1 November 2026. A number with no source beside it is a designers' rule of thumb, not a study.
- Wikipedia, Optimum HDTV viewing distance (SMPTE 30°, THX 40° and its 28–40° range, THX 15° screen height), read 31 Oct 2026
- Acoustic Frontiers, Home theater viewing angles, distances and sightlines (CEDIA 15° to the top or bottom), read 31 Oct 2026
- Journal of the ITE of Japan 65 (2011), preferred viewing distance for HD LCD TVs (abstract), checked 24 Oct 2026
Use this from an AI assistant
This answer as JSON, or as one paragraph with format=text: https://snuug.app/api/v1/tools/tv-height-distance
MCP server: https://snuug.app/mcp · OpenAPI · llms.txt. Every rule cites its source.