Resolution and files
Pixels, ppi, dpi, aspect ratio, JPEG and PNG, file-size limits, colour space and interpolation.
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Pick the size for the country you are applying to, or continue with the size you chose last.
Resolution and files
- Pixel
- One dot of colour in a digital image. The number of pixels decides how much detail a photo can hold.
- ppi (pixels per inch)
- How many pixels are packed into one printed inch. 300 ppi is the print standard that passport agencies and photo labs expect; 600 ppi holds more detail; 72 ppi is only for screens.
- dpi (dots per inch)
- How many ink dots a printer lays down per inch. The two are often used interchangeably for photos, which is why the UK states a 600 dpi requirement for its photos.
- Aspect ratio
- The relationship between width and height, such as 3:4 for 35×45 mm. Changing the aspect ratio stretches or squashes the face — always crop instead.
- JPEG
- A compressed image format accepted by almost every online form. Small files and broad compatibility, at the cost of some quality each time the file is re-saved.
- PNG
- A lossless format with sharp edges and optional transparency. Great for printing at home, but some forms reject it.
- File size
- How much space the file takes, in kB or MB. Government portals often require a range — for example India’s e-Visa wants 10 kB to 1 MB.
- sRGB
- The standard colour space for web and print photos. Converting to sRGB avoids the colour shifts you can get from camera-specific profiles.
- Interpolation
- Software inventing extra pixels when a photo is enlarged. It cannot add real detail, so start from the largest original you have.
More glossary pages
- Sizes and measurementMillimetres, inches, head height, framing and orientation — the measurements that decide whether a photo is accepted.
- Official standardsICAO, ICAO 9303, biometric photos and consular legalisation — who sets the rules and what they mean.
- Working with the cropperPreset, crop, print sheet, cutting guide and bleed — the words used by the cropping tool itself.
- Units at a glanceEvery common photo size converted to pixels at 300 ppi and 600 ppi, and the countries that use it.