2×2 inches (51×51 mm), white background, head 1-1⅜ inches from chin to top of head, neutral expression, no glasses, taken within the last 6 months.

Facial-recognition systems work best against a uniform background. The exact colour (white, off-white, light grey, plain blue) is country-specific.

Yes if the resolution is high enough (~600 DPI at the target physical size) and the framing matches the country requirements. The tool helps you crop and rescale to the right dimensions.

Most countries now prohibit eyeglasses entirely; older requirements allowed them only without glare. Check current rules on the issuing authority's site.

For online applications, you upload the file directly. For paper applications, you print at the specified DPI on photo paper — use the DPI adjuster to ensure correct print size.