About the TV Viewing Distance Calculator
How far you sit from a TV changes how immersive it feels. This calculator finds the recommended distance for a 16:9 screen from its diagonal size and the pixels across. It shows the THX cinema distance (40° of view), the SMPTE distance (30°), and the closest you can sit before single pixels become visible. Type the screen size in inches and its horizontal pixels and the TV viewing distance appears at once, with a few related figures underneath, and you can copy the result with one tap. The sums run in your browser, so nothing you enter is uploaded.
Updated October 2026
How to use the TV Viewing Distance Calculator
- 1Enter the screen size in inches and its horizontal pixels.
- 2Pick the units or options from the menus if the TV viewing distance tool offers them.
- 3Read the TV viewing distance in the large result box.
- 4Look at the extra rows for related figures.
- 5Press Copy result to keep the answer.
When you need the TV viewing distance
Shoppers use it to pick a TV size for their room, and installers use it to place a sofa.
A higher-resolution TV lets you sit closer without seeing pixels. A 4K TV looks the same at half the distance of a 1080p one for the same size.
How the TV viewing distance is worked out
The screen width = diagonal × 16 ÷ √(16² + 9²). THX distance = width ÷ (2 × tan 20°). SMPTE distance = width ÷ (2 × tan 15°). A 55-inch TV is about 48 inches wide. The THX distance is about 66 inches (5.5 ft), the SMPTE distance about 90 inches, and a 4K screen lets you sit as close as about 43 inches before you see pixels.
Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.
- THX and SMPTE
- Pixel limit
- Screen width and height
Mistakes to avoid with TV viewing distance
Good eyesight, room lighting and the type of content all change what feels right. Treat the numbers as a starting point, not a rule.
On phone and computer
On a phone, type into the boxes one after another and read the TV viewing distance underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the TV viewing distance move. The tv viewing distance calculator works the same on both.
Checking your TV viewing distance by hand
A good habit is to test the tv viewing distance calculator with a case you already know. A 55-inch TV is about 48 inches wide. The THX distance is about 66 inches (5.5 ft), the SMPTE distance about 90 inches, and a 4K screen lets you sit as close as about 43 inches before you see pixels.
If your own figures give a surprising answer, repeat the working yourself: The screen width = diagonal × 16 ÷ √(16² + 9²). THX distance = width ÷ (2 × tan 20°). SMPTE distance = width ÷ (2 × tan 15°). Small differences usually come from rounding, from mixing units, or from a typing slip in one of the inputs. Distance is one part of a good setup. Check the screen shape with the Aspect Ratio Calculator, see detail with the PPI Calculator, and find the diagonal with the Screen Size Checker.
Features
- 16:9 only
- Room light matters
- Use as a starting point
- Clear messages when the TV viewing distance inputs make no sense
- Copy the result with one tap
- Private: nothing is uploaded
Frequently asked questions
How do I calculate TV viewing distance?
The screen width = diagonal × 16 ÷ √(16² + 9²). THX distance = width ÷ (2 × tan 20°). SMPTE distance = width ÷ (2 × tan 15°). A 55-inch TV is about 48 inches wide. The THX distance is about 66 inches (5.5 ft), the SMPTE distance about 90 inches, and a 4K screen lets you sit as close as about 43 inches before you see pixels.
What is the formula for TV viewing distance?
The screen width = diagonal × 16 ÷ √(16² + 9²). THX distance = width ÷ (2 × tan 20°). SMPTE distance = width ÷ (2 × tan 15°). The tv viewing distance calculator applies it exactly and rounds only the displayed answer to six significant figures.
What is THX viewing distance?
The distance at which the screen fills 40 degrees of your view.
How close can I sit to a 4K TV?
About 1.0 to 1.5 times the screen's diagonal, depending on your eyes.
Does it work for 21:9 screens?
The tool assumes 16:9.
Is this tv viewing distance calculator free and private?
Yes. It is free, needs no account and runs in your browser, so the numbers you type are not uploaded or stored.