Photo size terms explained: DPI, pixels, cm

Exam forms mix up several units. Here's what each means, in plain words.

The terms

• Pixels (px) — the number of dots in the image (e.g. 413 × 531).
• cm / inch — the print size on paper.
• DPI — dots per inch; links pixels to print size (300 DPI is standard).
• KB — the file size on disk, what upload limits use.

How they connect

pixels = cm × DPI (÷2.54). So 3.5 × 4.5 cm at 300 DPI ≈ 413 × 531 px. Use the Photo Maker to set the exact px and KB your form needs — all on your device.