Calculator Tools
TV Viewing Distance Calculator
Find the recommended viewing distance for any TV size, or the best TV size for your room, using SMPTE, THX, and 4K sharpness guidelines.
What do you want to calculate?
Pick the inputs you already know. The other side updates automatically.
TV diagonal size
Measured corner to corner. Most TVs are sold by this number.
Common TV sizes
Aspect ratio
Almost every modern TV is 16:9. Cinema-style ultrawide screens use 21:9 or 2.39:1.
Resolution for pixel-floor check
The pixel floor is how close you can sit before individual pixels start to be visible.
About the recommended angles
- THX max (36 deg) is the closest distance THX recommends for reference movie viewing. Closer than this is usually too immersive for long sessions.
- SMPTE (30 deg) is the reference angle the Society of Motion Picture and Television Engineers cites for movie content. It is a good target for a single dedicated home theater seat.
- THX min (26 deg) is the far end of the THX cinematic range. The picture still feels like a theater, just a back-row seat.
- Casual (20 deg) is a comfortable everyday viewing angle for typical TV content.
- Beyond about 40 degrees most viewers have to turn their head to take in the whole frame.
How the math works
- width = diagonal x w / sqrt(w^2 + h^2)
- distance = (width / 2) / tan(angle / 2)
- size = 2 x distance x tan(angle / 2)
- The pixel floor uses the 20/20 acuity limit of 1 arcminute per pixel, so the closest sharp distance is width x 3438 / horizontalPixels.
- All length conversions use the exact international inch: 1 in = 2.54 cm = 25.4 mm.
All calculations run locally in your browser. Nothing you enter is uploaded. These figures are based on widely cited industry standards and viewing-acuity research; actual seating preferences vary, so use the numbers as a starting point.
How to use
- Pick whether you know the TV size (and want a recommended distance) or know the viewing distance (and want a recommended TV size).
- Enter a TV diagonal in inches or centimetres, or a viewing distance in feet or metres. Tap a preset to fill it in quickly.
- Pick the aspect ratio. Almost every modern TV is 16:9, but 21:9 and 2.39:1 are available for cinema-style ultrawide screens.
- In TV-size mode, pick a resolution to also see the pixel floor: the closest distance before individual pixels become visible.
- Read the recommended range, each standard's distance or size, and the visual distance map. Use Copy summary to grab a plain-text block.
About this tool
TV Viewing Distance Calculator answers two related questions homeowners and home-theater builders ask whenever they shop for a TV: how far back should I sit from a given size, and what size TV should I buy for a given distance. It works from the geometry of how much horizontal field of view the picture takes up at your eye, using the same standards the cinema industry uses: the Society of Motion Picture and Television Engineers (SMPTE EG-18) reference angle of about 30 degrees for movie viewing, the THX recommendations of 36 degrees as a maximum-immersive distance and 26 degrees as a cinematic minimum, and a more relaxed 20 degree casual TV angle for everyday content like news and sports. Pick a TV diagonal in inches or centimetres and an aspect ratio (16:9 covers almost every modern TV, with 21:9 and 2.39:1 available for cinema-style ultrawide displays), and the tool reports the picture width and height, the recommended viewing distance for each standard, the immersive ceiling beyond which most viewers have to turn their head to scan the frame, and the casual lower bound below which the TV starts to feel small. A 4K or 8K pixel-floor readout uses the standard 20/20 visual-acuity limit of about 1 arcminute per pixel to tell you the closest distance at which individual pixels become indistinguishable, which is a more useful answer than 'just sit further back' for anyone choosing between 1080p, 4K, and 8K. The reverse mode takes your measured viewing distance and reports the diagonal each standard recommends, so you can shop with a single number in mind instead of guessing between 55, 65, 75, and 85 inch options. A visual distance map plots each standard along a sweet-spot bar so you can see at a glance how the THX, SMPTE, and casual targets stack up for your TV, with the pixel floor overlaid when it falls inside the visible range. Common TV size and distance presets (32, 40, 43, 50, 55, 60, 65, 70, 75, 77, 85, and 98 inch panels; 5, 7, 9, 11, 13, and 15 foot seating distances) make it quick to scan a buying decision. A copy-summary button produces a clean plain-text block you can paste into a buying spreadsheet, a contractor email, or a partner conversation. Useful for shoppers comparing TV sizes, renters fitting a TV to a small living room, home-theater builders sizing a single dedicated viewing seat, and anyone setting up a bedroom or office mount. All math runs locally in your browser. Nothing you enter, including TV size, room measurements, or resolution, is uploaded, logged, or sent to any server. The recommendations are based on widely cited industry standards and viewing-acuity research; seating preferences vary, so use the numbers as a starting point.
Free to use. Works in your browser. No signup, no login.
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