Common baby ID photo sizes in one place.

Pixels, print size, and DPI are different measurements

Pixel dimensions describe the digital image. Millimetres and inches describe the physical print. DPI connects the two when printing, but changing a DPI label alone does not create additional image detail. Start with a sharp, high-resolution source and export the ratio requested by the receiving organization.

When printing a 4 x 6 sheet, disable “fit to page” and other automatic scaling options. Measure one finished photo before using the full batch. For online forms, upload the individual photo file rather than a photograph of a printed copy.

Worked example: a square photo on a 4 x 6 sheet

A 2 x 2 inch photo is 50.8 x 50.8 mm. At 300 pixels per inch it needs 600 x 600 pixels; the maker's 1200 x 1200 export has the same square shape and more pixels. Printing that export at 300 pixels per inch without setting its physical size would produce a 4 x 4 inch image, not a 2 x 2 inch photo.

Set the individual print to 2 x 2 inches, or use the prepared 4 x 6 sheet on 4 x 6 inch paper with automatic scaling disabled. Measure a finished copy before submitting it. Pixel count controls available detail; it does not guarantee either the printed dimensions or the head size inside the photo.

How to choose between common ratios

• Use 2 x 2 inches only when the instruction calls for a square document photo.
• Use 35 x 45 mm for documents that explicitly request that portrait format, not simply because it is common.
• Use 50 x 70 mm only for authorities that specify the larger portrait size.
• Treat China 1-inch and 2-inch presets as separate formats and confirm the exact local use before printing.