Quick answer

PPI means pixels per inch. It describes how many image pixels are assigned to each inch when calculating a physical display or print size.

Original example

Keep the pixels, change the size

A 3000-pixel-wide image calculates to 10 inches wide at 300 PPI and 20 inches wide at 150 PPI. The image still contains 3000 pixels in either calculation.

How PPI affects calculated print size

Divide a pixel dimension by PPI to estimate its length in inches. The result describes geometry, not a promise of visual quality.

PPI refers to image pixels. Printer DPI refers to physical ink or toner dots and should not be used as a substitute label for an image's pixel density.

Common misunderstandings

  • Editing only a PPI metadata value does not automatically create new image pixels.
  • There is no single PPI value that guarantees a good result for every printer, material, and viewing distance.

Related answers

Sources

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