Pixel Density Calculator (PPI)

How to calculate screen PPI

1. Enter the native horizontal and vertical pixel counts from the panel specification. Do not use a scaled desktop resolution or the browser viewport.
2. Enter the diagonal across the active image and choose inches or centimeters. Changing the unit reinterprets the number already entered; it does not convert it.
3. Read the approximate PPI. To compare, enable the second screen and enter its own resolution, diagonal and unit. Calculation details show pixel pitch and modeled panel dimensions.

What pixel density tells you

PPI means pixels per inch: the number of physical pixels along one inch of the screen. It is a linear density, not the total number of pixels in the panel.

For square pixels, the pixel diagonal is √(width² + height²). Divide it by the physical diagonal in inches. A centimeter diagonal is first divided by 2.54.

Pixel pitch is the distance between the centers of neighboring pixels: 25.4 divided by PPI gives millimeters. The width and height are modeled from the diagonal and native pixel proportions.

A higher PPI packs pixels more closely at the same physical length. Viewing distance, eyesight, rendering and other panel properties also affect what looks sharp; this calculator assigns no quality grade.

Worked screen examples

A 300 × 400 pixel screen with a 5-inch diagonal has 100 PPI. Its active area is approximately 3 × 4 inches, and the pixel pitch is 0.254 mm. A 12.7 cm diagonal gives the same result.

A 1920 × 1080 screen at 24 inches has about 91.79 PPI, with an active area of about 20.92 × 11.77 inches. At the same resolution, a larger diagonal lowers PPI.

A 2560 × 1440 screen at 27 inches has about 108.79 PPI: about 18.52% higher linear density than the 24-inch Full HD example. At 32 inches, the same 2560 × 1440 resolution has approximately the same density as that first screen.

Assumptions and rounding

The model assumes a flat rectangular active area with square physical pixels. It does not account for non-square pixels, subpixel layouts, curved or folded measurement conventions, VR optics, casing size or printer DPI.

PPI and dimensions normally show up to two decimal places; pixel pitch shows up to four. Very small positive values use a “less than” threshold, and large values use up to six significant digits without scientific notation. Comparison uses unrounded values; differences below 0.01% are described as approximately the same.

Your entries and copying

The arithmetic runs in your browser without uploading the entered screen specifications. Entries are not saved in this tool or added to its URL. Copy includes the current valid result and public page link; with an incomplete second screen, it includes screen 1 only. The surrounding site may still load ads, analytics and consent services.