What Is Image Resolution? Pixels, DPI, PPI and Dimensions Explained

The Great Resolution Confusion

Few topics in digital media create as much confusion as resolution. People frequently ask: "Why does my 300 DPI image look tiny?" or "How many megapixels do I need to print an 8 × 10 photo?"

To master image editing, you must separate digital dimensions (pixels) from physical output resolution (DPI and PPI).

Pixels, PPI and DPI Defined

Pixel (px): The fundamental building block of a digital raster image. A 1920 × 1080 image has exactly 2,073,600 pixels, regardless of whether it is viewed on a 6-inch phone or a 65-inch TV.

PPI (Pixels Per Inch): Measures pixel density on digital display screens. Higher PPI values (like 460 PPI on modern smartphones) mean individual pixels are microscopic, resulting in lifelike sharpness.

DPI (Dots Per Inch): A physical printing term describing how many physical droplets of ink a printer lays down per inch of paper.

The Myth of "72 DPI for Web"

A persistent myth claims web images must be saved at "72 DPI". In reality, web browsers completely ignore the DPI metadata header inside an image file! A 1200 × 800 image set to 72 DPI and the exact same 1200 × 800 image set to 300 DPI will display at the identical size on any web page.

What matters for web performance is purely the pixel dimensions (width × height) and compression file size.