PPI / DPI Calculator
Pixels per inch (PPI) is a measure of pixel density that describes how many individual pixels fit within one inch of a display. A higher PPI means more detail is packed into the same physical area, resulting in sharper, crisper images. This calculator computes PPI from a screen's resolution (width and height in pixels) and its physical diagonal size in inches using the formula PPI = √(width² + height²) / diagonal.
Beyond PPI, this tool also calculates dot pitch — the physical distance between the centers of adjacent pixels in millimeters — and the total resolution in megapixels. These metrics are essential when comparing monitors, choosing a phone or tablet, evaluating camera sensors, or printing at the correct resolution. A display with PPI above 200 is generally considered high-DPI or Retina-class, where individual pixels become imperceptible to the naked eye at normal viewing distances.
How it works
PPI = √(horizontal_pixels² + vertical_pixels²) / diagonal_inches. Dot pitch (mm) = 25.4 / PPI. Megapixels = (horizontal_pixels × vertical_pixels) / 1,000,000.
Use cases
- Comparing the sharpness of monitors, TVs, and mobile displays
- Determining whether a screen qualifies as Retina or high-DPI
- Calculating print resolution requirements for photos and graphics
- Evaluating camera sensor pixel density and image clarity
- Choosing the right display for graphic design, video editing, or gaming