PPI Calculator

Understanding PPI (Pixels Per Inch)

PPI stands for Pixels Per Inch. It is a measurement of the pixel density (resolution) of an electronic image device, such as a computer monitor or television display, or image digitizing device such as a camera or image scanner.

Higher PPI generally means a sharper image because there are more pixels packed into every square inch of the display. If you hold two phones of the same physical size side-by-side, the one with 450 PPI will look significantly sharper than one with 300 PPI.

How to Calculate PPI

To calculate the PPI of a screen, you need two pieces of information: the resolution (width and height in pixels) and the diagonal size of the screen in inches.

We use the Pythagorean theorem to find the diagonal resolution:

Diagonal Pixels = √(Width² + Height²)
PPI = Diagonal Pixels / Diagonal Size (Inches)

Common PPI Standards

• Standard Desktop (72-96 PPI): Older monitors and some large desktop screens. Images designed for the web often assume this baseline, though modern screens vary widely.
• Standard Laptops (1080p @ 13-15"): Typically ranges between 110 PPI to 140 PPI. Good for general productivity.
• Full HD TVs (1080p @ 40-50"): Often around 44 PPI. Because you sit far from the TV, you don't notice the lower density.
• Retina / Mobile (300+ PPI): Apple's "Retina" standard generally refers to a pixel density high enough that the human eye cannot distinguish individual pixels at a normal viewing distance (usually around 300 PPI for phones).
• High-End Monitors (1440p/4K @ 27"): These can reach 100 PPI (1440p) to 163 PPI (4K), providing extremely crisp text and graphics.

PPI vs. DPI

While often used interchangeably in casual conversation, PPI refers to digital screens (pixels), while DPI (Dots Per Inch) refers to physical printing (dots of ink). In printing, a standard quality is 300 DPI. However, a 300 PPI screen is much sharper than a 300 DPI print because pixels can have color gradients, whereas ink dots are usually cyan, magenta, yellow, or black.