Pakistan, Schengen and UK windows want 35×45 mm. The US wants 2×2 in. Passport Photo Maker exports those pixel sizes with a background fill.
Compose so the head sits in the upper two-thirds. We do not auto-detect faces — that keeps the tool offline and predictable. Use Background Remover first if the wall is busy, then fill white or light grey.
Print at the official millimetre size, not “fit to page”. A 600×600 px 2×2 in image is 300 dpi, which photo counters accept.