From centimetres to pixels: how 3.5 × 4.5 cm becomes 413 × 531
Korea’s passport photo requirement is specified physically, as 3.5 × 4.5 cm, the standard size a photo studio would print. For an online application that accepts a digital upload instead of a physical print, that physical size has to be converted into a pixel grid, and the conversion depends on an assumed print resolution. At 300 DPI (dots per inch) — the standard resolution for print-quality output — 3.5 cm and 4.5 cm work out to 413 × 531 pixels: (3.5 ÷ 2.54) × 300 ≈ 413, and (4.5 ÷ 2.54) × 300 ≈ 531. That’s the pixel grid this page produces.
Online application vs. printed photo
There’s a meaningful difference between uploading a digital photo for the online passport application and bringing a printed photo to a passport office in person. This page is built for the online path — the pixel dimensions above are what the online system expects from a digital file. If you’re instead having a photo printed at a studio or a photo booth, the studio will typically handle the sizing themselves from a physical print template, and the pixel numbers here aren’t directly relevant to that process.
No published file size limit
Unlike most of the exam requirements on this site, the Korean passport photo guidance published by the Ministry of Foreign Affairs doesn’t specify a minimum or maximum file size — only the pixel dimensions and general photo requirements (plain background, neutral expression, no glasses glare, taken within the last six months). Because of that, this tool doesn’t enforce a byte-size target for this page; it simply resizes to 413 × 531 pixels and encodes at a quality high enough to look clean at that size, cropping from the centre if your source photo isn’t already close to the 3.5:4.5 ratio.