What is DPI?

DPI stands for dots per inch. It describes how densely something is printed: how many dots of ink a printer places in one inch of paper. In everyday use, people also say DPI when they mean the resolution saved inside an image file.

DPI in an image file

A digital image has a fixed number of pixels, for example 3000 × 2000. On its own, that image has no physical size. The DPI value saved in the file adds one instruction: how many pixels should fit in one inch when it is printed.

• At 300 DPI, 3000 pixels become 10 inches.
• At 150 DPI, the same 3000 pixels become 20 inches.
• At 72 DPI, they become almost 42 inches.

The pixels never change. Only the printed size does, and with it how sharp the print looks up close.

Why print shops ask for 300 DPI

At normal reading distance, the human eye stops seeing individual pixels at around 300 per inch. That makes 300 DPI the safe standard for photos, flyers, cards and anything people hold in their hands. It is a rule of thumb, not a law: photo labs often accept 240 DPI, and posters seen from a few meters look fine at 150 DPI or less.

Does DPI matter on screens?

No. Screens show pixels one to one, so a website, a social media post or a presentation ignores the DPI stored in the file. The old idea that web images must be 72 DPI comes from early monitors and has no effect today.

Common values

• 72 or 96 DPI: the default many phones, cameras and apps write. Not a sign of low quality.
• 150 DPI: large posters and banners seen from a distance.
• 300 DPI: the print standard for photos and documents.
• 600 DPI and more: scans, line art and text, where crisp edges matter.

How to check or change it

Use our DPI checker to see the DPI and pixel size of any image, and the DPI changer to set it to 300 or any other value. If you need to know how many pixels a print size requires, the DPI calculator does the math. For the technical difference between DPI and PPI, read DPI vs PPI.