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Screen Viewing Distance Calculator

Works out how close you can sit before pixels become visible, and the distances for immersive and cinema-standard viewing.

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Lab tool
Enter your figures and press Calculate distances.
In short Beyond a certain distance your eye cannot resolve individual pixels, and that distance is what decides whether a resolution upgrade will be visible at all. The limit used here is one arcminute, the standard figure for 20/20 vision, and it is what produces the well-known result that 4K on a 24-inch monitor is wasted at normal desk distance while the same panel at 27 inches and closer is not. For a television the arithmetic is more brutal: most living-room sofas are far enough away that 4K and 1080p are indistinguishable on a 55-inch set, which is why the upgrade so often disappoints. The immersive distances are a different question and answer it from the other end. THX recommends a 40° horizontal field of view and SMPTE 30°, and both put you considerably closer than most people sit — the goal there is not resolving detail but filling enough of your vision that the frame stops feeling like a window. Two caveats. The acuity figure assumes 20/20 vision, so anyone sharper sees pixels further away and anyone with worse eyesight sees fewer. And content matters: text and interfaces reveal pixel structure at distances where film never will.

How to use the Screen Viewing Distance Calculator

  1. Enter your figures in the input fields.
  2. The result updates as you type, together with the full working.
  3. Check the breakdown table to see exactly how the number was reached.

About the Screen Viewing Distance Calculator

The Screen Viewing Distance Calculator works out how close you can sit before pixels become visible, and the distances for immersive and cinema-standard viewing. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.

What people use it for

  • Deciding whether 4K is worth paying for at a given screen size.
  • Choosing a television size for a room you have already measured.
  • Working out whether a monitor is too large for your desk depth.

Details

Acuity limit used1 arcminute (20/20 vision)
THX immersive40° horizontal field of view
SMPTE cinema30° horizontal field of view

The maths behind it

This tool uses the distance at which one pixel subtends one arcminute — roughly 3438 divided by the pixels per inch, in inches. Every intermediate value is shown on screen, so the result can be checked by hand.

Explained in our guides

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Frequently asked questions

Is 4K worth it on a 24-inch monitor?
Run the numbers and see: at that size the pixel-free distance is well under normal desk range, meaning a 1440p panel already looks continuous where you sit. On a 32-inch monitor at the same desk the answer usually flips.
Why do the cinema distances suggest sitting so close?
They answer a different question. The acuity figure is about whether you can see pixels; the THX and SMPTE figures are about how much of your vision the screen fills, which is what makes film feel immersive. For a desk monitor the acuity number is the useful one.
Does this account for my eyesight?
It assumes 20/20. Better than average vision resolves finer detail and pushes the distance further out; if you wear glasses for distance, the practical figure is closer than the calculation.
Are there any usage caps on the Screen Viewing Distance Calculator?
No charge and no sign-up. There is no free tier to run out of because there is no paid tier — inputtesthub.com is funded by advertising rather than by metering the tool.
Is the Screen Viewing Distance Calculator safe to use with private information?
No. The Screen Viewing Distance Calculator runs entirely in your browser using JavaScript. Nothing is transmitted, logged or stored, which you can verify yourself in the Network tab of your browser's developer tools.
Can I check the maths myself?
It uses the distance at which one pixel subtends one arcminute — roughly 3438 divided by the pixels per inch, in inches. The full working is printed under the result, so you can follow every step rather than trusting a black box.
What is the Screen Viewing Distance Calculator used for?
In practice it gets used for three things: deciding whether 4K is worth paying for at a given screen size. Choosing a television size for a room you have already measured. Working out whether a monitor is too large for your desk depth. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
What figures does the Screen Viewing Distance Calculator work from?
Acuity limit used is 1 arcminute (20/20 vision). THX immersive is 40° horizontal field of view. SMPTE cinema is 30° horizontal field of view. These are printed on the page itself, so you do not have to take them on trust.
How precise is the result?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.

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