TV Viewing Distance CalculatorFree online other calculator — instant results, no sign-up
Find viewing distance for a chosen horizontal field of view.
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About the TV Viewing Distance Calculator
The TV Viewing Distance Calculator finds how far to sit from a TV so its screen spans your chosen horizontal field of view. It uses the screen diagonal and assumes a flat, 16:9 screen. With the default 55-inch diagonal and 30-degree horizontal field of view, the calculated distance is 89.451015 in.
- Screen diagonal (in)
- The corner-to-corner measurement of the visible screen in inches, with a default of 55.
- Horizontal field of view (degrees)
- The angle the screen's full width should span at your eyes in degrees, with a default of 30.
Formula and method
W = D × 16 / √(16² + 9²); L = W / [2 × tan(θ × π / 360)]. For D = 55 and θ = 30: L = (55 × 16 / √337) / [2 × tan(30 × π / 360)] ≈ 89.451015 in.
- DScreen diagonal in inches.
- WScreen width in inches, derived using the assumed 16:9 aspect ratio.
- θDesired full horizontal field of view in degrees.
- LViewing distance in inches, measured from your eyes straight to the screen center.
- πThe mathematical constant pi; π / 180 converts degrees to radians.
First, convert the diagonal into screen width using the proportions of a 16:9 rectangle. Split the viewing geometry into two right triangles, each with half the screen width opposite half the horizontal viewing angle. Divide half the screen width by the tangent of half the angle to obtain the viewing distance.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Screen diagonal55 in
- Horizontal field of view30 degrees
Results
- Result89.451015 in
How to use the TV Viewing Distance Calculator
- 1Measure the visible screen diagonally in inches, excluding the bezel.
- 2Enter that measurement in Screen diagonal (in); leave 55 to reproduce the default example.
- 3Enter your desired Horizontal field of view (degrees); leave 30 for the default example.
- 4Read the calculated Result: the default inputs produce 89.451015 in.
- 5Use this distance as an eye-to-screen placement guide, then adjust your seating for comfort.
Reading your result
The Result row reports the viewing distance in inches required to achieve the selected horizontal field of view. For a 55-inch, 16:9 screen at 30 degrees, Result = 89.451015 in. Sitting closer makes the screen span a wider angle; sitting farther away makes it span a narrower angle. The displayed decimal precision describes the calculation, not the precision needed when positioning a chair.
Limitations
The calculation assumes a flat 16:9 screen and a viewer centered directly in front of it, with the viewing direction perpendicular to the screen. Other aspect ratios, curved screens, and off-center seating require different geometry. The diagonal must be positive, and the horizontal field of view must be greater than 0 and less than 180 degrees; extreme angles may be impractical. This is a geometric distance, not a guarantee of viewing comfort or a health recommendation, and it does not account for resolution, eyesight, content, or room layout.
Common questions
Why does the calculator need the diagonal when the field of view is horizontal?+
TV sizes are usually specified by diagonal. The calculator converts that diagonal to width using a 16:9 aspect ratio, then uses the width to calculate the horizontal viewing angle.
Does a larger horizontal field of view mean sitting closer?+
Yes. For the same TV, increasing the requested angle reduces the calculated distance because the screen must occupy more of your horizontal view.
Should I measure the distance from the sofa or from my eyes?+
Measure from your eyes in your usual seated position to the center of the screen. The sofa's front edge or backrest may not match that position.
Does the default result change for a 4K TV?+
No. A 55-inch, 16:9 TV at a 30-degree horizontal field of view gives 89.451015 in regardless of resolution. Resolution can affect visible detail and seating preferences, but it does not change this geometry.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
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Results are estimates for informational purposes and are not financial, medical or legal advice.