How to Check Image DPI on Windows, Mac, and Online

How to Check Image DPI on Windows, Mac, and Online DPI (dots per inch) is the one number that separates a crisp printed photo from a pixelated mess. Before you send images to a printer, submit them for a passport, or upload to a print-on-demand service, you need to know what DPI you're working with. Here's how to check the DPI of any image on Windows, Mac, or directly in your browser — no software installation required. What Is DPI? DPI stands for dots per inch. It measures how many ink dots a printer places within one inch of printed output. More dots per inch = more detail = sharper print. For digital screens, the equivalent term is PPI (pixels per inch), but DPI is used loosely for both. When someone asks "what DPI is this image?", they're asking how many pixels exist per inch when the image is printed at its native size. A 300 DPI image at 4×6 inches contains 1,200 × 1,800 pixels. Shrink the print size, the effective DPI goes up. Enlarge it, the DPI drops. DPI is not a fixed proper