Retina Distance Calculator

About the Retina Distance Calculator

Retina distance is the closest viewing distance where typical 20/20 vision can no longer distinguish individual pixels. This calculator combines screen size, resolution and visual acuity to estimate when a display looks pixel-free, then helps translate that into monitor and TV buying decisions.

How to Use

1. Choose a calculation mode: "Screen to Distance" calculates your screen's Retina distance, "Distance to TV" recommends a suitable TV size.
2. Mode 1: Enter the screen's diagonal size (inches) and resolution, or enter a PPI value directly.
3. Mode 2: Enter your viewing distance and resolution preference, and choose your preferred viewing experience.
4. Review the results, including PPI, Retina distance, and a comparison with Apple device standards.

Formula

PPI = √(width px² + height px²) ÷ diagonal size (inches). Retina distance (inches) = 3438 ÷ PPI, or in metric units, Retina distance (cm) = 8733 ÷ PPI. This formula is derived from the human eye's resolving limit of about 1 arcminute.

Frequently Asked Questions

What is Retina Display?

Retina Display is Apple terminology for a screen dense enough that individual pixels are not visible at normal viewing distance. Apple defines this as roughly 300 PPI when viewed from 10-12 inches away.

How close do I need to sit to see 4K detail?

For example, a 55" 4K TV has a Retina distance of about 43 inches (109 cm). You need to sit within that distance to truly notice 4K's advantage over 1080p. Beyond about 10 feet (3 meters), the difference between 1080p and 4K becomes hard to see.

What's the difference between THX and SMPTE recommendations?

THX recommends a 40° viewing angle for a cinema-style immersive experience, ideal for movie enthusiasts. SMPTE recommends a 30° viewing angle for comfortable viewing, better suited to everyday and long-duration use.

How do I choose a TV size for my living room?

Use Mode 2 ("Distance to TV"): enter the distance from your sofa to the TV, select 4K and your preferred viewing experience, and you'll get a recommended size. As a rule of thumb, a 10-foot (3 m) viewing distance suits a 65-75" TV.

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