TV Size Calculator 2026: The Best Size for Your Seat

A bigger TV is not always a better picture. Past a certain size, from where you sit, the pixels become visible and the picture starts to look soft; below a certain size, 4K's extra detail is finer than your eyes can see. Both sizes are geometry, and this TV size calculator works them out.

Put in how far you sit from the screen, the picture you will watch, and a size you are looking at. It works out the largest TV that looks fully sharp from your seat, the size above which 4K looks sharper than 1080p, and how much of your view the TV fills. It uses the ITU's rule that one pixel should take up no more than one arcminute, every figure it supplies names its source, and the list of what it cannot tell you is below the answer.

In this guide

1. The TV size calculator
2. Where every number here comes from
3. What this cannot tell you
4. What that viewing angle means for your room
5. Questions about the TV size calculator
6. Sources

The TV size calculator

Where every number here comes from

No part of this was measured on a bench here. This site works from published specifications and from what owners report, and every number below is either one you typed in or a published figure with its source named next to it.

The figures this page supplies

• Inches in a foot: 12 in. NIST: since 1 July 1959 the international foot is defined as 0.3048 m and the inch as 25.4 mm, so a foot is 12 inches by definition.
• Distances per unit of size at one arcminute: 3,437.7500. One arcminute is the angle 20/20 vision just resolves, the definition behind the Snellen 20/20 line and the basis of ITU-R BT.1845. 1 / tan(1 arcminute) is 3437.75, so a detail becomes too small to see at 3437.75 times its own size.
• TV picture shape, across: 16. ITU-R BT.709 (HDTV) and ITU-R BT.2020 (4K and 8K) both set the picture aspect ratio at 16:9, the shape TVs are sold in.
• TV picture shape, down: 9. The 9 of ITU-R BT.709's and BT.2020's 16:9.
• Rows of pixels in a 1080p picture: 1,080 px. ITU-R BT.709 sets HDTV at 1920 by 1080 pixels, 1080 active lines.
• ITU's optimal viewing angle for 1080p: 32 degrees. ITU-R BT.1845, Table 1: 1920 by 1080 at 16:9, an optimal horizontal viewing angle of 32 degrees at an optimal viewing distance of 3.1 times the picture height.
• ITU's optimal viewing angle for 4K: 58 degrees. ITU-R BT.1845, Table 1: 3840 by 2160 at 16:9, an optimal horizontal viewing angle of 58 degrees at an optimal viewing distance of 1.5 times the picture height.

Why each step is the step it is

• Your distance in inches: dist_ft * in_per_ft. Feet times 12.
• Largest TV that looks fully sharp from your seat: dist_in * res_h / arcmin_in * diag_units / ref_h. ITU-R BT.1845's rule read the other way round: at your distance a pixel can be 1/3437.75 of it before 20/20 vision sees it, the picture is that many pixels tall, and a 16:9 diagonal is the height times 18.36 over 9. Any TV up to this size shows no visible pixels from your seat.
• Largest TV on which 1080p looks fully sharp from your seat: dist_in * hd_rows / arcmin_in * diag_units / ref_h. The same sum for a 1080-row picture. Bigger than this, a 1080p picture shows its pixels from your seat, so this is the size above which a 4K picture looks visibly sharper than a 1080p one.
• Picture width of the TV you are looking at: size_in * ref_w / diag_units. TVs are sold by the picture's diagonal; the width is that diagonal scaled by 16 over the shape's diagonal.
• Picture height of the TV you are looking at: size_in * ref_h / diag_units. The same proportion taken down the screen: 9 over the shape's diagonal.
• The TV you are looking at fills this much of your view: 2 * Math.atan(width_in / 2 / dist_in) * 180 / Math.PI. Plain trigonometry on the picture width and your distance. ITU-R BT.1845 puts the optimal angle at 32 degrees for 1080p and 58 for 4K, which is what to read it against.
• One pixel of it, seen from your seat: arcmin_in * height_in / res_h / dist_in. The pixel's height over your distance, in arcminutes. At 1.00 you are exactly at the limit 20/20 vision resolves; below 1.00 the pixels are too small to see.
• Its pixels stop showing from: arcmin_in * height_in / res_h / in_per_ft. 3437.75 times one pixel's height, in feet: BT.1845's optimal viewing distance for this size and resolution. Sitting closer, the pixel grid can be seen.
• A 1080p picture on it looks fully sharp from: arcmin_in * height_in / hd_rows / in_per_ft. The same distance for a 1080-row picture. Sitting further away than this, 20/20 vision cannot tell a 4K picture on this TV from a 1080p one.

What this cannot tell you

Every calculator has an edge, and a page that hides its edge is worse than no page at all. Here is this one's.

• It is geometry, not a verdict on any TV. Brightness, contrast, colour, motion and the picture processing are not in this arithmetic, and this site has not had any of these TVs in its hands.
• Fully sharp means the pixels are too small for 20/20 vision to see. Better eyesight sees finer detail and moves every figure towards a smaller TV or a closer seat; weaker eyesight moves them the other way.
• It counts the picture's own resolution. Much of what is streamed or broadcast is compressed, or upscaled from 1080p or less, and then the detail on screen is less than the resolution says.
• It assumes a flat 16:9 picture seen square on. Films in a wider shape fill less of the height, and a seat well off to the side sees a narrower picture than this works out.
• The size on the box is usually rounded, and the stand and bezel are not counted, so the furniture needs a little more room than the picture width here; the maker's specification sheet has the exact figures.

What that viewing angle means for your room

These follow from the answer above and nothing else. Each heading below covers one span of results, so read the one the calculator pointed you at and ignore the rest.

Under 20 degrees: a small picture from that seat

The TV takes up a small part of your view, and every pixel is far below what the eye can see. If the room allows it, a bigger TV or a closer seat gives a picture that feels larger without looking any less sharp; the largest-sharp line above says how far you can go.

Roku Streaming Stick 4K vs Apple TV 4K, Which Is Worth It covers this range in full.

20 to 32 degrees: up to ITU's angle for 1080p

Up to the 32 degrees ITU-R BT.1845 gives as the optimal angle for a 1080p picture. Here a 1080p picture already looks fully sharp, so a 4K picture adds little that 20/20 vision can see. A 4K streaming device is still worth it for the HDR and the streaming apps' best picture, which the guides below compare.

Roku Streaming Stick 4K vs Apple TV 4K, Which Is Worth It covers this range in full.

Roku Streaming Stick 4K vs Fire TV Stick 4K Max vs Apple TV 4K, Best Pick covers this range in full.

32 to 58 degrees: where 4K shows

Between ITU's optimal angles for 1080p and for 4K. A 1080p picture shows its pixels from here, and a 4K picture does not, so this is the range where 4K is worth paying for. A picture this big often outgrows the TV's own speakers, which is where a soundbar comes in.

Best Soundbar for TV (2026): 3 Picks by Budget covers this range in full.

sound-bars-for-tv-2026 covers this range in full.

Roku Streaming Stick 4K vs Fire TV Stick 4K Max vs Apple TV 4K, Best Pick covers this range in full.

More than 58 degrees: past ITU's angle for 4K

Wider than the 58 degrees ITU gives for a 4K picture, so even 4K's pixels can be seen from your seat. Sitting a little further back, or a slightly smaller TV, brings the picture back to fully sharp. An 8K picture holds up closer than 4K does, but very little is filmed or streamed in 8K.

Best Soundbar for TV (2026): 3 Picks by Budget covers this range in full.

If you are comparing a TV with a monitor, or a different shape of screen, the aspect ratio calculator works out width and height for any ratio. A TV size calculator can only be as right as the distance you give it, so measure from the seat you use most rather than guessing.

Questions about the TV size calculator

What size TV should I get for my viewing distance?

The size at which the pixels stop being visible from your seat is the most a TV can grow before its picture starts to look soft. From 9 feet, a 4K picture looks fully sharp on a TV up to 138 inches, and a 1080p picture up to 69 inches. From 6 feet the limits are 92 and 46 inches. This TV size calculator works it out from ITU-R BT.1845's rule that one pixel should take up no more than one arcminute, the detail 20/20 vision resolves.

How far should you sit from a 65-inch TV?

For a 4K picture, at least 4.2 feet away: closer than that, 20/20 vision can see the pixel grid. For a 1080p picture on the same TV it is 8.5 feet. An 85-inch 4K TV needs 5.5 feet. That is ITU-R BT.1845's optimal viewing distance, where one pixel takes up one arcminute, so it is the closest seat with no visible pixels; sitting further back is fine, the picture just fills less of your view.

Is 4K worth it on a 65-inch TV at 9 feet?

Not by this arithmetic. On a 65-inch TV a 1080p picture already looks fully sharp from 8.5 feet, so at 9 feet 20/20 vision cannot tell 4K from 1080p. Move to 6 feet and one 1080p pixel is 1.41 arcminutes, big enough to see, and 4K's extra detail shows. From 9 feet, any TV bigger than 69 inches shows 1080p's pixels, so the larger the TV, the more 4K is worth.

How big is a 65-inch TV in width and height?

A TV's size is the diagonal of its 16:9 picture, so a 65-inch TV's picture is 56.7 inches wide and 31.9 inches tall. An 85-inch one is 74.1 by 41.7 inches, and a 55-inch one 47.9 by 27. The stand and the bezel add to that, so check the maker's specification sheet before measuring the furniture.

How much of your view should a TV fill?

ITU-R BT.1845 puts the optimal angle at 32 degrees for a 1080p picture and 58 degrees for 4K, the angles at which each one's pixels are just too small to see. A 65-inch TV seen from 9 feet fills 29 degrees, and an 85-inch one from the same seat fills 38. Below those angles the picture holds detail finer than 20/20 vision resolves from that seat, so a bigger TV or a closer seat makes more use of the resolution.

Sources

• ITU-R Recommendation BT.1845: guidelines on metrics for the optimal viewing distance and angle: Defines the optimal viewing distance as the one at which two adjacent pixels subtend one arcminute, and tabulates 3.1 picture heights and 32 degrees for 1080p, 1.5 picture heights and 58 degrees for 4K.
• ITU-R Recommendation BT.709: parameter values for the HDTV standards: Sets the 1920 by 1080 picture and its 16:9 shape.
• ITU-R Recommendation BT.2020: parameter values for UHDTV systems: Sets the 3840 by 2160 (4K) and 7680 by 4320 (8K) pictures, both 16:9.
• Snellen visual acuity and the one-arcminute limit: 20/20 vision is defined as resolving detail that subtends one arcminute, which is where the 3437.75 comes from.
• NIST: SI units, length: The inch and the foot as defined since 1959, which give the 12 inches to the foot used here.

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