Pixel Density Converter

Convert between PPI, pixels per centimetre, and dot pitch — to compare display sharpness across phones, monitors, and TVs.

Pixel Density / Dot Pitch

ppi, ppcm, dot pitch

From

Result

0.393701

1 ppi = 0.39370079 ppcm

Popular conversions

What Is a Pixel Density Converter?

A pixel density converter translates display sharpness measures between units — pixels per inch to pixels per centimetre, and to dot pitch (the spacing between pixels). Pixel density tells you how finely packed a screen's pixels are, which determines how sharp it looks. The most common unit is PPI (pixels per inch); dot pitch is its inverse, the distance between adjacent pixels, usually in millimetres.

This converter routes through PPI. The key relationship is reciprocal: dot pitch (mm) = 25.4 ÷ PPI, because higher density means smaller spacing between pixels. From a ~100 PPI desktop monitor to a 460 PPI phone (a 'Retina' display), pixel density is what separates a crisp screen from a visibly pixelated one.

This is one category of the full Unit Converter — pair it with our percentage calculator or scientific calculator for related everyday maths.

How Pixel Density Conversion Works

Everything routes through PPI

Each unit relates to pixels per inch. The converter normalises to PPI, then projects to pixels per centimetre and dot pitch.

PPI to PPcm uses 2.54

Since an inch is 2.54 cm, pixels per centimetre = PPI ÷ 2.54. A 254 PPI screen is 100 pixels per cm.

Dot pitch is the inverse

Dot pitch (mm) = 25.4 ÷ PPI. Higher density means a smaller pitch — pixels packed closer together.

PPI from resolution and size

PPI = √(width² + height²) in pixels ÷ diagonal in inches. It links a screen's resolution and physical size to its sharpness.

Core Pixel Density Conversion Factors

PPI is the anchor; dot pitch is its reciprocal.

PPI → PPcm

÷ 2.54

Pixels per inch divided by 2.54 gives pixels per centimetre.

PPI → dot pitch

25.4 / PPI

Dot pitch in mm is 25.4 divided by PPI — the inverse relationship.

PPI from screen

√(w² + h²) / diagonal

Diagonal pixel count divided by the screen's diagonal in inches.

How to Use the Pixel Density Converter

1
Enter the density value
Type the pixel density you want to convert — a screen's PPI, a pixels-per-cm figure, or a dot pitch.
2
Choose the 'from' unit
Pick PPI, pixels per centimetre, or dot pitch (mm) as your starting unit.
3
Choose the 'to' unit
Select the target unit, or swap the two to reverse direction.
4
Read every unit at once
The all-units table shows the density in PPI, PPcm, and dot pitch together for display comparisons.

Key Pixel Density Concepts

PPI (pixels per inch)

The standard density unit: how many pixels fit in a linear inch. Higher PPI means a sharper image — phones reach 400–500+ PPI.

Dot pitch

The distance between the centres of adjacent pixels, usually in mm. The inverse of density: a 0.25 mm dot pitch is about 102 PPI.

Retina / HiDPI

Densities high enough that individual pixels aren't visible at normal viewing distance — roughly 300+ PPI for a phone held at arm's length.

DPI vs PPI

DPI (dots per inch) is a printing term; PPI (pixels per inch) is for displays. They're often conflated but describe print and screen respectively.

Real-World Pixel Density Conversions

📱

Smartphone screens

A modern phone at 460 PPI has a 0.055 mm dot pitch. High density makes text and images look razor-sharp.

🖥️

Desktop monitors

A 27-inch 1440p monitor is ~109 PPI (0.233 mm pitch); a 4K 27-inch is ~163 PPI. Density drives perceived sharpness.

📺

Televisions

A 55-inch 4K TV is only ~80 PPI, but viewed from across a room it looks sharp — viewing distance matters as much as density.

💻

Retina laptops

A 'Retina' laptop display runs ~220–250 PPI, double a standard screen, so individual pixels vanish at normal distance.

🎮

VR headsets

VR displays push 1,000+ PPI to look sharp centimetres from the eye. Dot pitch shrinks to tens of microns.

🖨️

Print vs screen

Print uses 300 DPI; screens 72–460 PPI. Converting clarifies why a screen image may look soft when printed.

Best Practices for Pixel Density Conversion

✓Remember dot pitch is the inverse. Higher PPI means smaller dot pitch (pitch = 25.4 ÷ PPI). They move in opposite directions, so don't treat them as a linear scale.
✓Use 2.54 for PPI ↔ PPcm. An inch is 2.54 cm, so divide PPI by 2.54 for pixels per centimetre. A clean, exact factor.
✓Factor in viewing distance. Required PPI for 'sharp' falls with distance. A TV needs far less density than a phone because it's viewed much farther away.
✓Don't confuse DPI with PPI. DPI is a print term, PPI a display one. Comparing a 300 DPI print spec to a screen's PPI needs care about what each measures.
✓Compute PPI from resolution and size. To find a screen's density, divide its diagonal pixel count by its diagonal in inches — resolution alone doesn't tell you sharpness.

Common Pixel Density Conversion Mistakes

Treating dot pitch like density

Dot pitch is the inverse of PPI. A larger pitch means lower density, so reading them in the same direction is backwards.

Confusing resolution with density

A 4K resolution isn't a density — a 4K phone and a 4K TV have wildly different PPI because of their sizes.

Mixing DPI and PPI

DPI (print dots) and PPI (screen pixels) aren't the same. Comparing a print DPI directly to a screen PPI misleads.

Ignoring viewing distance

Judging sharpness by PPI alone ignores distance. A low-PPI billboard looks crisp far away; a phone needs high PPI up close.

Why Pixel Density Conversion Matters

Pixel density is what makes a screen look sharp or pixelated, and it's compared across phones, monitors, TVs, and VR headsets using PPI, pixels per centimetre, and dot pitch. Because dot pitch is the inverse of PPI, and because resolution alone says nothing about sharpness without screen size, converting correctly is key to meaningful display comparisons.

As displays span from ~80 PPI TVs to 1,000+ PPI VR panels, and as designers target multiple densities, fluent conversion between PPI, PPcm, and dot pitch underpins device specs, design assets, and print-versus-screen decisions. A converter that routes through PPI and exposes the reciprocal dot pitch turns sharpness comparisons into a clear, checkable number.

Built for display engineers, UI/UX and print designers, and tech buyers converting between PPI, pixels per centimetre, and dot pitch.

Linear unit factors follow the BIPM SI brochure, the NIST Guide to the SI, and ISO 80000. Currency rates load live from open.er-api.com; crypto prices from CoinGecko. See our methodology and editorial policy. Educational only — not certified for regulated trading, settlement, medical, or aerospace use.

Pixel Density Converter FAQs

Divide 25.4 by the PPI to get dot pitch in millimetres, because the two are reciprocals. So a 100 PPI screen has a dot pitch of 25.4 ÷ 100 = 0.254 mm, and a 460 PPI phone has about 0.055 mm. Higher density means a smaller pitch — pixels packed more closely together.

PPI (pixels per inch) measures pixel density — how many pixels fit into a linear inch of screen. Higher PPI means a sharper image because pixels are smaller and harder to distinguish. Phones reach 400–500+ PPI, desktop monitors around 100–160 PPI, and TVs often under 100 PPI.

Divide the diagonal resolution in pixels by the screen's diagonal size in inches. The diagonal pixel count is √(width² + height²). For a 27-inch 2560×1440 monitor: √(2560² + 1440²) ÷ 27 ≈ 109 PPI. So resolution and physical size together determine density.

PPI (pixels per inch) describes display pixel density, while DPI (dots per inch) describes printer output resolution. They're often used interchangeably, but DPI refers to ink dots on paper and PPI to pixels on a screen. A 300 DPI print and a 300 PPI screen are not directly comparable.

Roughly, a display is 'Retina' or HiDPI when its pixels aren't individually distinguishable at the normal viewing distance — about 300+ PPI for a phone held at arm's length, but lower for screens viewed farther away. There's no single PPI threshold; it depends on how far the screen is from your eyes.

It uses exact relationships (1 inch = 2.54 cm = 25.4 mm, dot pitch = 25.4 ÷ PPI) and routes every conversion through PPI at full precision, so the result is exact to your input precision.