The digital and printed specifications are different shapes
This is the trap, and it is in the official guidance rather than in anybody's interpretation of it. The printed photo is 35 × 45 mm, an aspect ratio of 0.778. The digital minimum is 600 × 750 pixels, an aspect ratio of 0.800. Those are not the same rectangle.
Produce a file at exactly 600 × 750 and you have a photo of the wrong proportions — slightly too wide for its height — which is the shape that gets applications refused. The two numbers cannot both be treated as the specification, and the resolution is that 600 × 750 is a floor on each axis independently while the shape comes from the printed size.
So the correct minimum digital file is not 600 × 750. It is 601 × 772: the height raised until the width, at the printed aspect ratio, clears its own 600-pixel floor. Almost nobody does this, which is why so many home-cropped photos are subtly the wrong shape.
Head height is a proportion, not a pixel count
The 29–34 mm head measurement is given for the printed photo, and no equivalent is published in pixels — because it does not need to be. Within a 45 mm frame it means the head occupies between 64% and 76% of the height, and a proportion holds at any resolution.
That is why the same crop produces both a correct print and a correct upload. Work in millimetres and you have to redo the arithmetic for every output size; work in the proportion and you do it once.
Inches, for printers that ask
35 × 45 mm is 1.378 × 1.772 inches. Nobody sells paper in that size, which is why photos are printed several to a 6 × 4 inch sheet and cut out. If a print dialog offers you 1.4 × 1.8 inches as a close-enough option, it is not close enough: 1.4 inches is 35.6 mm and 1.8 is 45.7 mm, and the head measurement moves with the frame.
The file size floor is a real requirement
Between 50 KB and 10 MB. The ceiling is obvious and the floor is not, and it is the floor that catches people: an image compressed hard enough to look fine on a phone can fall under 50 KB and be refused for it. If you have compressed a photo to make it upload faster, check what you ended up with.
Printing several at once
A 35 × 45 mm photo is not a paper size anybody sells, so prints are produced several to a sheet and cut out. On 6 × 4 inch photo paper at 300 DPI, 6 fit in a 3 × 2 grid, each occupying 413 × 531 pixels of the 1800 × 1200 sheet. There is more on that, including the print setting that quietly ruins it, on the printing page.
Where these numbers come from
Verified on 2026-08-10 against GOV.UK — Get a passport photo . The dimensions live in one file in this project and are checked by an automated test on every change, so the tables above and the tool cannot disagree with each other. They can both be out of date, which is why the date is on the page and the source is linked.
Frequently asked questions
What size is a UK passport photo in mm?
45 mm high by 35 mm wide for a print. Inside that, the head must measure 29–34 mm from the bottom of the chin to the crown of the skull — not the top of the hair.
What size is a UK passport photo in pixels?
At least 600 pixels wide and 750 tall, and between 50 KB and 10 MB. But 600 × 750 is not the right shape for a UK photo: it is 0.800 where the printed specification is 0.778. The smallest file that satisfies both the pixel floor and the correct proportions is 601 × 772.
What size is a UK passport photo in inches?
1.378 × 1.772 inches, which is 35 × 45 mm. It is not a standard paper size, so prints are produced several to a 6 × 4 sheet and trimmed.
Is a UK passport photo the same size as a US one?
No, and they are not even the same shape. The UK photo is a 35 × 45 mm rectangle; the US photo is a 2 × 2 inch square, which is 51 × 51 mm. A UK photo cannot be cropped from a US one or the reverse without changing the head proportion as well.
What DPI should a printed passport photo be?
300 DPI is the practical answer. At 300 dots per inch a 35 mm width is 413 pixels, which is below the 600-pixel digital floor but perfectly adequate on paper — the eye stops resolving detail at around that density at reading distance. Print files and upload files are answering different questions.