What is the difference between DPI and PPI?

PPI (pixels per inch) measures the pixel density of a screen display — how many pixels fit in one inch of screen. DPI (dots per inch) technically refers to print resolution — how many ink dots a printer places per inch. In practice, "DPI" is often used interchangeably with "PPI" for screens. This calculator computes PPI from screen resolution and size.

What PPI is considered Retina?

Apple defines Retina as a display where individual pixels are indistinguishable at normal viewing distance. For phones (held at ~10-12 inches), this is about 300+ PPI. For laptops (~18 inches), it is about 200+ PPI. For desktop monitors (~24 inches), about 110+ PPI qualifies. The iPhone 15 Pro has 461 PPI; MacBook Pro 14" has 254 PPI.

How do I calculate PPI from resolution and screen size?

PPI = diagonal resolution in pixels / diagonal size in inches. First calculate diagonal pixels: sqrt(width^2 + height^2). For a 1920x1080 display at 24 inches: sqrt(1920^2 + 1080^2) = 2203 pixels diagonal. PPI = 2203 / 24 = 91.8 PPI. This calculator does this math automatically.

Does higher PPI mean better image quality?

Higher PPI means more pixels per inch, which produces sharper text and images. However, the benefit depends on viewing distance. A 92 PPI monitor looks sharp at 24+ inches, but a phone at 10 inches needs 300+ PPI to look equally sharp. Beyond a threshold, higher PPI has diminishing returns — the human eye cannot distinguish individual pixels.

What PPI do I need for printing?

For high-quality print, 300 DPI is the standard. Magazine and photo printing use 300 DPI. Large format prints (posters, banners) can use 150-200 DPI because they are viewed from farther away. Newspaper print uses 150 DPI. For web images displayed on screen, 72-96 PPI is sufficient.

Why does my 4K monitor at 27 inches only show 163 PPI?

A 4K (3840x2160) monitor at 27 inches has 163 PPI because the pixels are spread over a larger physical area. The same 4K resolution on a 15.6-inch laptop would be 282 PPI. Physical screen size directly affects pixel density: larger screens at the same resolution have lower PPI. For 27-inch monitors, 4K is still very sharp for desktop use.

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DPI/PPI Calculator

DPI (dots per inch) and PPI (pixels per inch) measure screen pixel density. PPI = diagonal pixels / diagonal inches. A 1920x1080 display at 24 inches = 92 PPI. A 2560x1440 at 27 inches = 109 PPI. Apple Retina displays exceed 200 PPI (MacBook Pro 14" = 254 PPI). Higher PPI means sharper text and images. For print, 300 DPI is standard quality.

Calculate screen DPI (dots per inch) and PPI (pixels per inch) from resolution and screen size. Enter width, height in pixels, and diagonal in inches. Shows PPI, megapixels, aspect ratio, and quality rating. Presets for iPhone, MacBook, 4K monitors.

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Presets

Screen Specifications

Width (pixels)

Height (pixels)

Diagonal (inches)

DPI/PPI Reference

PPI Range	Quality	Typical Usage
< 100 PPI	Low	Large monitors, TVs viewed from distance
100-150 PPI	Standard	Desktop monitors, standard laptops
150-200 PPI	Good	High-end laptops, some tablets
200-300 PPI	High (Retina)	MacBooks, iPads, premium laptops
300-400 PPI	Very High	Modern smartphones
400+ PPI	Ultra High	Flagship phones, VR headsets

How to Use

1
Enter screen resolution
Type the width and height in pixels (e.g., 1920 x 1080). Or click a device preset like iPhone 15 Pro or 4K Monitor 27".
2
Enter screen diagonal
Type the screen diagonal size in inches (e.g., 24 for a 24-inch monitor, 6.1 for an iPhone).
3
Read the results
See PPI (pixels per inch), DPI, megapixels, total pixel count, aspect ratio, and quality rating (Standard, Good, High/Retina, Ultra High).
4
Copy the results
Click Copy to copy all calculated values. Compare devices or use the PPI value for design decisions.

Frequently Asked Questions

What is the difference between DPI and PPI?: PPI (pixels per inch) measures the pixel density of a screen display — how many pixels fit in one inch of screen. DPI (dots per inch) technically refers to print resolution — how many ink dots a printer places per inch. In practice, "DPI" is often used interchangeably with "PPI" for screens. This calculator computes PPI from screen resolution and size.
What PPI is considered Retina?: Apple defines Retina as a display where individual pixels are indistinguishable at normal viewing distance. For phones (held at ~10-12 inches), this is about 300+ PPI. For laptops (~18 inches), it is about 200+ PPI. For desktop monitors (~24 inches), about 110+ PPI qualifies. The iPhone 15 Pro has 461 PPI; MacBook Pro 14" has 254 PPI.
How do I calculate PPI from resolution and screen size?: PPI = diagonal resolution in pixels / diagonal size in inches. First calculate diagonal pixels: sqrt(width^2 + height^2). For a 1920x1080 display at 24 inches: sqrt(1920^2 + 1080^2) = 2203 pixels diagonal. PPI = 2203 / 24 = 91.8 PPI. This calculator does this math automatically.
Does higher PPI mean better image quality?: Higher PPI means more pixels per inch, which produces sharper text and images. However, the benefit depends on viewing distance. A 92 PPI monitor looks sharp at 24+ inches, but a phone at 10 inches needs 300+ PPI to look equally sharp. Beyond a threshold, higher PPI has diminishing returns — the human eye cannot distinguish individual pixels.
What PPI do I need for printing?: For high-quality print, 300 DPI is the standard. Magazine and photo printing use 300 DPI. Large format prints (posters, banners) can use 150-200 DPI because they are viewed from farther away. Newspaper print uses 150 DPI. For web images displayed on screen, 72-96 PPI is sufficient.
Why does my 4K monitor at 27 inches only show 163 PPI?: A 4K (3840x2160) monitor at 27 inches has 163 PPI because the pixels are spread over a larger physical area. The same 4K resolution on a 15.6-inch laptop would be 282 PPI. Physical screen size directly affects pixel density: larger screens at the same resolution have lower PPI. For 27-inch monitors, 4K is still very sharp for desktop use.