US Passport Photo — 2×2 inch

The US spec is unusual twice over: the frame is square (51×51 mm) where most of the world uses 35×45, and the tolerance is generous-looking but strictly enforced — the head must measure 25 to 35 mm from chin to crown, with eyes between roughly 28 and 35 mm from the photo's bottom edge. Photos from other countries' formats cannot be reused; a 35×45 crop scaled to square distorts nothing but the odds of acceptance.

Digital submissions have their own gate. The online systems accept a square JPEG between 600×600 and 1200×1200 pixels, at most 240 KB, in sRGB. That byte ceiling is the silent killer: a sharp 1200×1200 photo of a detailed background can refuse to fit, and generic tools then quietly downscale or over-compress. This exporter runs a binary search over quality to land inside the window at full allowed resolution and tells you the exact bytes it achieved.

The instruction most people have not read: travel.state.gov tells applicants not to change the photo "using computer software, phone apps or filters, or artificial intelligence". Glasses have been banned since 2016 outside documented medical need; smiles beyond neutral, shadows on the face or background, and head coverings without religious or medical grounds round out the common refusal reasons. This page therefore measures and crops — the background check verifies your actual wall reads as plain white or off-white, rather than painting one in.

Lighting for the white background is the practical hurdle at home: stand 40–50 cm off the wall, put the light source behind the camera rather than overhead, and the ΔE uniformity check here will tell you numerically whether the shadow you cannot quite see will read as one to an examiner.