How to Calculate DPI (PPI) — Step by Step
DPI (dots per inch) — also commonly called PPI (pixels per inch) when talking about screens — measures pixel density. Higher DPI means more detail packed into the same physical space, resulting in sharper images and text.
Using the DPI Calculator for Monitors & Laptops
Find your screen’s resolution in Windows (Display settings) or macOS (About This Mac > Displays), then enter the pixel width, pixel height, and the marketed diagonal size (usually 13", 15", 24", 27", or 32"). The tool will compute exact pixel density and help you compare sharpness across devices.
How to Calculate Print DPI (Scanner, Camera, or Photo)
For printed images, use the pixel dimensions of the source file and the printed physical size. A 4×6 inch print made from a 1800×1200 px image has a lower PPI than the same print from a 3600×2400 px image. Use this calculator to check whether your photo or scan will print crisp at the intended size.
What’s a “Good” PPI?
- 72–96 PPI: Standard web/screen baseline.
- 150–200 PPI: Acceptable for basic print and large-format posters viewed up close.
- 300 PPI: Preferred for high-quality photographic prints.
- 600+ PPI: Scanned documents and high-density mobile displays.