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Study shows: Our eyes resolve more pixels than assumed

29.10.2025

Translation: machine translated

The previous benchmark for a "sharp" display was 60 pixels per degree of field of view. A new study shows that many people can perceive higher pixel densities. Nevertheless, 8K TVs remain pretty pointless.

In cooperation with Meta, the University of Cambridge has recently determined the maximum detail perception of the human eye. The result: grey scales are resolved with up to 94 pixels per degree (PPD), red-green patterns with 89 PPD, yellow-violet with 53 PPD. This means that the visual acuity is significantly higher than the previous standard value of 60 PPD.

PPD (pixels per degree) describes how many pixels the eye sees per degree of viewing angle. The value depends on the display size, resolution and viewing distance and measures the perceived sharpness. In practice, PPD is therefore more important than PPI (pixels per inch). Although PPI indicates the physical pixel density of a panel per inch, it does not take the viewing distance into account. As a reference: in a typical office scenario with a sitting distance of 80 centimetres, a 27-inch monitor with 4K resolution achieves around 90 PPD.

The researchers used a test setup with a movable display and varied distances up to around 1.6 metres. They measured the line spacing up to which the test subjects were still able to recognise differences. The team then used the series of measurements to derive threshold values above which 95 per cent of the population no longer recognised any advantage.

The minimum viewing distance for different display sizes and resolutions at which 95 per cent of people no longer see higher pixel densities.
Source: University of Cambridge

A 60-inch display with 4K resolution, for example, is already above the visual performance of most test subjects at a distance of three metres. Additional pixels do not make the image subjectively sharper. Smartphones, tablets, AR and VR displays are typically viewed from shorter distances, which is why PPD limits are more likely to be exceeded here. On the iPad Pro with a 13-inch display, the PPD at a distance of 35 centimetres is around 65 - i.e. at the limits of perception. Meta's VR headset Quest 3 only achieves 25 PPD on typical faces.

Useful online calculator

To calculate the PPD of your personal display scenario, the research team provides an online calculator. The tool shows the proportion of people who still see a difference to a «perfect» display under the conditions. A few practical examples:

XXL TV (77 inch, 4K, 3 metre distance): 118 PPD, only 2 per cent of people would still perceive a higher resolution.
Large monitor (32 inch, 4K, 1 metre distance): 95 PPD, 53 per cent of people would perceive a higher resolution as sharper
Smartphone (6.3 inches, 2856 × 1280 pixels, 40 centimetres distance): 137 PPD, 0 per cent of people could recognise a higher pixel density

The authors conclude that a higher resolution is not always better. If the PPD exceeds the limits of human perception in the typical usage scenario of a display, it is of little benefit. At the same time, costs, energy consumption and the required rendering effort increase. An 8K TV, for example, is pretty pointless - unless you look at it from a distance of less than 1.3 times its height.

Header image: Samuel Buchmann

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Samuel Buchmann

Senior Editor

Samuel.Buchmann@digitecgalaxus.ch

My fingerprint often changes so drastically that my MacBook doesn't recognise it anymore. The reason? If I'm not clinging to a monitor or camera, I'm probably clinging to a rockface by the tips of my fingers.

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