Understanding The Relationship between Pixel Pitch and Optimal Viewing

Viewing Distance

One important consideration in choosing the right pixel pitch for your video wall is knowing the distance between the audience and the LED display. This is a highly subjective topic. However, there are various methods and guidelines to determine the optimal viewing distance, and often take different factors into account and consideration.

1. Visual Acuity Distance
Occasionally called "Pixel Recognition Range," denotes the distance at which a person with standard 20/20 vision should stand from an LED screen to not see individual pixels. It refers to the clarity or sharpness of vision when looking at objects from a specific distance. In eye exams, visual acuity is typically tested with a standard chart (like the Snellen chart) that has letters of varying sizes, and the individual is usually positioned 20 feet away from the chart in the U.S. or 6 meters in many other countries.

The result of this test is often expressed as a fraction, like 20/20 in the U.S. The first number (the numerator) refers to the distance the person is from the chart, which is typically 20 feet. The second number (the denominator) indicates the smallest line of letters that the person can read. A person with 20/20 vision can see clearly at 20 feet what should normally be seen at that distance. If someone has 20/40 vision, it means they need to be 20 feet away to see what a person with normal vision can see at 40 feet.

It's essential to note that visual acuity is just one component of vision. Other aspects, like peripheral vision, depth perception, and color vision, are also crucial to overall visual health and functionality.

How To Calculate Visual Acuity Distance
Using a benchmark of 1 arc minute for 20/20 vision, which is equivalent to 3438. Here is an example calculation: 2.50mm (pixel pitch) multiplied by 3438 = 28.1 ft. (which was a conversion of Visual Acuity Distance from mm to feet). See visual illustration below.

2. The 10x Rule
The 10x Rule is a shorthand method for roughly calculating Visual Acuity Distance. As per this rule, the minimum viewing distance for an LED video wall is roughly 10 times the pixel pitch. Therefore, a LED video wall that has a pixel pitch of 2.5mm would have an optimal viewing distance from 25 feet away, as illustrated below.

However, it's important to understand that this is a general rule of thumb and the actual ideal viewing distance can vary based on several factors, including the content being displayed, the quality of the LEDs, the ambient light conditions, and the specific requirements of the installation.

3. Average Comfortable Viewing Distance
This refers to the distance at which most viewers will perceive the LED screen's visuals to be acceptable (not optimal or ideal). It is influenced by factors like individual vision, screen application, content resolution, and the kind of content being diplayed (whether text or video). It takes into consideration various data that has been derived from many real-life setups and installations.

This method is much more forgiving than Visual Acuity Distance, in that it roughly cuts the viewing distance from the LED video wall in half for the same pixel pitch size. For example, the optimal viewing distance from the video wall for a 1mm pixel pitch based on Visual Acuity Distance is 11.3 feet. The distance recommended by the Average Comfortable Viewing Distance is almost half that. Meaning, for a 1mm pixel pitch, the acceptable viewing distance from the video wall would only be 5.8 feet away (versus 11.3 feet by Visual Acuity Distance)..

Our pixel pitch calculator below is based on the Visual Acuity Method. Simply plug in the closet viewing distance to see what pixel pitch would be best for the video wall when it comes to optimal viewing.