Display Spec Comparator
Compare two screens honestly — pixel density, real physical dimensions, and the distance beyond which extra resolution stops being visible.
The "sharp beyond" distance is where 20/20 vision can no longer resolve individual pixels (the one-arcminute rule: 3438 ÷ PPI inches). Sit farther than that and extra resolution is invisible — the honest reason an 8K TV rarely earns its price at couch distance.
More pixels and sharper are different axes
A 24-inch 1080p monitor and a 32-inch 1440p monitor have exactly the same pixel density — 91.79 PPI, not approximately. 2560/1920 is 4/3 and 32/24 is also 4/3, so the two cancel perfectly. The 1440p screen shows 78% more and is not one bit sharper: it is a bigger window on the same-sized text, which is a real upgrade and not the one the resolution number implies.
| Screen | Density | Pixels | Sharp beyond |
|---|---|---|---|
| 13" laptop, 2560 × 1600 | 232.2 PPI | 4.10 MP | 1.23 ft |
| 27" 4K | 163.2 PPI | 8.29 MP | 1.76 ft |
| 32" 4K | 137.7 PPI | 8.29 MP | 2.08 ft |
| 27" 1440p | 108.8 PPI | 3.69 MP | 2.63 ft |
| 24" 1080p | 91.8 PPI | 2.07 MP | 3.12 ft |
| 32" 1440p | 91.8 PPI | 3.69 MP | 3.12 ft |
| 55" 4K television | 80.1 PPI | 8.29 MP | 3.58 ft |
The comparison runs the other way too. A 55-inch 4K television is 80 PPI — less dense than that 24-inch 1080p monitor, despite having four times the pixels. Rank the list by pixel count and by density and you get two different orders, which is why neither number alone answers "is this a better screen". Density only means something once you say how far away you are sitting: the laptop is sharp from 1.2 feet, the television from 3.6, and both are fine where they are actually used.
Where the "sharp beyond" number comes from
That column divides 3438 by the density, and the constant is not arbitrary: it is the number of arcminutes in a radian, 60 × 180 / π = 3437.75. It encodes the usual definition of 20/20 vision — detail one arcminute across is the finest a normal eye resolves. So the distance shown is where one pixel subtends exactly one arcminute. Past it, someone with average sight cannot pick out individual pixels; closer, they can. It is a fact about eyes rather than about screens, which is why the same number sits behind every "retina display" claim ever made — and why a phone held at arm's length and a billboard seen from a road can both qualify.
And the diagonal is a poor way to sell a screen
Screens are advertised by their diagonal, which is the one measurement that does not tell you how much screen there is. For a fixed diagonal the area is ar / (1 + ar²) times the diagonal squared, and that peaks at a square:
| Shape | Area for a given diagonal | Against a 16:9 |
|---|---|---|
| 1:1 | 0.5000 × diag² | 117% |
| 4:3 | 0.4800 × diag² | 112% |
| 16:10 | 0.4494 × diag² | 105% |
| 16:9 | 0.4273 × diag² | 100% |
| 21:9 | 0.3621 × diag² | 85% |
| 32:9 | 0.2606 × diag² | 61% |
A square gets the most out of a given diagonal — 17% more than a 16:9 — and every step away from square costs area. A 32:9 at the same diagonal has 39% less glass. Even the common case bites: a 34-inch 21:9 ultrawide has 15% less area than a 34-inch 16:9, because every inch the shape stretches sideways is bought from the height. The comparison above gives physical width and height for exactly this reason. If you are choosing between shapes, those two numbers are the ones to read.
How to use
- Enter each display's diagonal size and resolution.
- Compare pixel density and physical dimensions.
- Check the distance at which the difference stops mattering.
- Consider panel quality alongside the numbers.
Frequently asked questions
What is pixel density and why does it matter?
Pixels per inch — how finely packed the display is. It determines whether individual pixels are visible at your viewing distance, which is what governs whether text looks crisp. Two screens at the same resolution can look very different if their sizes differ.
At what point does more resolution stop being visible?
It depends entirely on viewing distance, which is why the question has no single answer. Human acuity resolves roughly one arcminute, so the further away a screen is the less density it needs — a phone at 30 cm needs far more than a television across a room.
Is a bigger screen always better?
Not for a monitor at desk distance, where a very large display forces head movement to see the edges and can be genuinely tiring. Beyond a point the useful upgrade is resolution or panel quality rather than size, which is the opposite of how displays are marketed.
Why is the advertised size not the visible size?
Because it is the diagonal, and diagonal alone does not determine width and height — aspect ratio does. A 27-inch 16:9 monitor is about 60 cm wide, while an ultrawide of the same diagonal is wider and shorter. Comparing diagonals across aspect ratios misleads.
Does refresh rate matter more than resolution?
For fast-moving content, frequently yes. Motion clarity improves noticeably up to and beyond 120 hertz, and many people find the difference more apparent than an increase in resolution. For text and static work, resolution and panel quality dominate.
What do the numbers not tell me?
A great deal. Contrast ratio, colour accuracy, brightness, uniformity, viewing angles and coating all affect how a display actually looks, and none appear in size and resolution. Two identical-specification panels can differ substantially in practice.
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