TV Mounting Height Calculator

Background.

Mounting height is the decision people get wrong most often, and the reason is that the wall suggests one answer while the geometry gives another. A fireplace, a picture rail or a run of cabinets says "put it here"; your eyes say something quite different. This calculator does the arithmetic that turns a seated eye height and a seating distance into the two numbers you need — where the centre of the screen should be, and therefore where the bottom edge lands on the wall.

The published constraint comes from THX. On its own site, THX writes: "For optimal viewing, you want your line of sight to be more or less aligned with the center of the screen. We suggest 15 degrees or less, above or below the center." It adds a warning about elevation specifically: "If you elevate your TV, you're going to distort the picture quality", because LCD panels shift in contrast and colour off-axis. That 15-degree figure is a recommendation from a certification body rather than a formal standard, and this page labels it as such throughout — but it is a published, checkable number, which is more than most mounting advice offers.

Turning it into a height takes one line of trigonometry. If your eyes are e inches above the floor and you sit d inches back, the highest the screen centre can go while staying within 15 degrees is e + d × tan 15°, which is e + 0.2679·d. At a nine-foot seat that is 28.9 inches of headroom above your eye line. Subtract half the picture height — for a 16:9 panel, 4.5 ÷ √337 = 0.245 times the diagonal — and you have the highest the bottom edge can go.

That subtraction is where the surprise lives. Because half the picture height grows with the screen, the ceiling on the bottom edge *falls* as the television gets bigger. With eyes at 42 inches and a nine-foot seat, a 55-inch set can have its bottom edge as high as 57.5 inches; a 65-inch set only 55.0; an 85-inch set only 50.1. The common instinct — that a bigger screen can be hung higher because you can see more of it — is exactly backwards. A bigger screen has to come down.

The three modes answer three real questions. Eye level puts the centre exactly on your eye line for a zero-degree angle, which is the ideal and, for a large panel, often puts the bottom edge lower than people expect — around 26 inches for a 65-inch set, which is media-unit height rather than wall height. The maximum-tilt mode gives the highest position that still qualifies, for rooms where the wall genuinely forces a compromise. The check mode takes a position you have already chosen and tells you the angle it produces and how far outside the limit it is.

One input dominates everything: seated eye height. This page does not assume one. No primary anthropometric source for floor-to-eye height while seated could be obtained, and deriving one from published sitting-height data would require assumptions about seat height and head geometry that would amount to guessing. So measure yours — sit where you watch, have someone measure floor to eye, and use that. The 42-inch default is a placeholder, and a sofa six inches lower than average moves every output on this page by six inches.

The bracket itself is a separate matter. Wall mounts attach through the VESA Flat Display Mounting Interface, whose published overview defines mounting interfaces for displays from 4 to 90 inches diagonal, with Part F covering 31 to 90 inch panels weighing up to 113.6 kg (250 lbs). Check your panel's weight against the mount's rating and the wall's capacity before any of this geometry matters.

What is tv mounting height calculator?

TV mounting height is the height above the floor at which a wall-mounted screen is fixed, normally quoted either as the height of the bottom edge — the number you can measure once the panel is up — or as the height of the screen's centre, which is what the mounting geometry is really based on.

The quantity that determines whether a height is right is not the height itself but the angle between your seated eye line and the centre of the screen. THX recommends keeping that within 15 degrees, above or below. Because the centre of a screen sits half a picture height above its bottom edge, and because a 16:9 panel's picture height is 0.4903 times its diagonal, converting between the two is a fixed multiple of the screen size — and that is why the highest permissible bottom-edge height drops as the screen gets larger.

How to use this calculator.

1. 01Measure your seated eye height: sit where you actually watch and have someone measure from the floor to your eyes. This matters more than any other input.
2. 02Measure the distance from that seat to the wall the screen will hang on.
3. 03Enter the screen's advertised diagonal — a 16:9 shape is assumed.
4. 04Leave the mode on eye level for the ideal answer, and read the bottom-edge height. For a large panel this is often lower than the wall suggests.
5. 05If the wall forces the screen higher, switch to the maximum-tilt mode to see the highest position that still sits inside THX's 15-degree guidance.
6. 06To test a position you have already picked — over a fireplace, for instance — switch to the check mode and enter the planned bottom-edge height.
7. 07Check the top-edge output against any ceiling, beam or sloped roof before drilling.
8. 08Confirm the panel's weight against the mount's VESA rating and the wall's fixings independently; the geometry says nothing about whether the wall will hold it.

The formula.

Start with the panel. A 16:9 screen of diagonal D has sides 16k and 9k with (16k)² + (9k)² = D², so k = D ÷ √337 and the picture height is H = 9D ÷ √337 = 0.4903 D. Half of that, 0.2451 D, is the distance from the bottom edge to the centre — the conversion between the two heights this page reports.

Now the angle. Your eye is at height e and the screen centre at height c, separated horizontally by the seating distance d. The line of sight to the centre rises by c − e over a run of d, so the vertical viewing angle is θ = arctan((c − e) ÷ d). A positive θ means looking up. Setting |θ| ≤ 15° and solving for c gives the ceiling c_max = e + d·tan 15°, with tan 15° = 0.2679491924. The corresponding limit on the bottom edge is b_max = c_max − H ÷ 2.

Notice what does and does not depend on the screen size. The ceiling on the *centre* depends only on your eye height and how far back you sit — a 32-inch monitor and an 85-inch television have exactly the same maximum centre height in the same room. The ceiling on the *bottom edge* subtracts half the picture height from that, so it falls by 0.2451 inches for every inch of extra diagonal. Going from a 55-inch to an 85-inch panel lowers the highest legal bottom edge by 0.2451 × 30 = 7.4 inches.

The three modes simply choose c. Eye level sets c = e, which makes θ exactly zero. Maximum tilt sets c = c_max, which makes θ exactly 15 degrees. The check mode sets c from a planned bottom edge, c = b_planned + H ÷ 2, and reports whatever angle falls out. All three then report the same bottom, top, picture height and ceilings, so switching modes changes the recommendation without changing the frame of reference.

A worked example.

Frequently asked questions.

References& sources.

1. [1]THX Ltd — 'Where and how should I position my TV in my living room?': 'For optimal viewing, you want your line of sight to be more or less aligned with the center of the screen. We suggest 15 degrees or less, above or below the center', and 'If you elevate your TV, you're going to distort the picture quality.'
2. [2]THX Ltd — 'What size TV should I buy for my living room?': measure the distance between couch and TV in inches, then multiply by .835 to get the screen size — the horizontal counterpart to the vertical rule used here.
3. [3]VESA — Flat Display Mounting Interface (FDMI) Overview: the standard defines mounting interfaces for flat displays from 102 mm (4") to 2286 mm (90") diagonal, with Part D (12"–22.9", up to 14 kg / 30.8 lbs), Part E (23"–30.9", up to 22.7 kg / 50 lbs) and Part F (31"–90", up to 113.6 kg / 250 lbs), and both centre-mounted and edge-mounted hole patterns.
4. [4]Recommendation ITU-R BT.709-6 (06/2015), Table 1 — aspect ratio 16:9 with 1:1 (square) pixels, the panel shape assumed by the picture-height calculation. International Telecommunication Union.