Getting a passport or visa photo to the exact size a form wants

Passport and visa portals reject photos for reasons they rarely explain, and the underlying problem is almost always a units mismatch. The specification is written in millimetres, your photo is measured in pixels, and the thing that connects them is DPI — a number the form may or may not mention. Get that conversion wrong and you submit something that is the right shape and the wrong size, or the right size and too coarse to print. The arithmetic is one multiplication, but you have to know which numbers to put in it. Requirements also differ by country and change without notice, so this is about the method rather than a table of measurements: check your issuing authority's current specification, then use what follows to hit it exactly.

The one calculation

Millimetres, pixels and DPI are three views of the same image:

pixels = millimetres ÷ 25.4 × DPI

The 25.4 is millimetres per inch. DPI (dots per inch) is the printing density, and it is the number people leave out.

Take the common 35 × 45 mm photo at 600 DPI:

• Width: 35 ÷ 25.4 × 600 = 827 px
• Height: 45 ÷ 25.4 × 600 = 1063 px

At 300 DPI the same photo is 413 × 531 px. Same physical print, half the pixels. This is why "35 × 45 mm" on its own does not tell you what to produce — and why two people following the same spec can submit files that differ by a factor of four.

If the form gives you pixel dimensions directly, use those and ignore DPI entirely. If it gives millimetres and a DPI, run the calculation. If it gives millimetres and no DPI, 600 is a safe assumption for something that will be printed, and 300 is the minimum worth submitting.

Get the aspect ratio right first

Before any resizing, crop to the correct proportions. A 35 × 45 mm photo has a ratio of about 1:1.286; a 2 × 2 inch photo is square.

If you resize a photo whose ratio does not match, one of two bad things happens. Either the tool stretches it — which distorts the face, and facial distortion is an explicit rejection reason in most photo standards — or it letterboxes it, leaving bands that break the framing rules about head position.

So crop first, to the target ratio, with the head positioned as the specification requires. Most standards define both the head height as a proportion of the image and the space above the head, and getting the crop right is what satisfies those. Then resize the correctly-proportioned crop to the exact pixel dimensions, with aspect-ratio lock on so nothing shifts.

Then hit the file size

Photo portals frequently cap file size aggressively — commonly a few hundred kilobytes, sometimes under 100 KB — and they enforce it after all the dimension rules, so this is the last step rather than the first.

The order matters. Crop, resize to the exact pixels, and only then compress to fit the size cap. Compressing before resizing means you compress data you are about to throw away, then compress again afterwards, which costs quality twice for no benefit.

Watch the background as you lower quality. Passport photos are shot against plain light backgrounds, and flat areas are exactly where JPEG compression shows first — a clean background develops blotches and faint banding well before anything else in the frame looks wrong. If the background starts to mottle, you have gone too far; go back and reduce the pixel dimensions slightly instead, if the spec allows any latitude.

Format, and the iPhone problem

Nearly every photo portal accepts JPG and many accept nothing else.

Photos taken on an iPhone are HEIC by default, which almost nothing outside Apple's ecosystem reads, so the upload fails with an unhelpful error even when the dimensions and size are perfect. Convert HEIC to JPG before you start — and do it first, because there is no point tuning a file that will be rejected on its extension.

Avoid PNG for photographs here even where it is accepted. It is lossless, so files are several times larger for no visible gain, which fights directly against the size cap.

Things that get photos rejected beyond the numbers

Getting the file right is necessary and not sufficient. The rejections that survive correct dimensions are almost always about the photograph itself:

• Shadows — on the face, or cast onto the background behind the subject. This is the most common failure by a distance, and it comes from a single light source or from standing too close to the wall.
• Background — must be plain and even. A wall that looks uniform to your eye often is not to a reviewer, particularly with a shadow gradient across it.
• Expression and eyes — neutral expression, mouth closed, eyes open and clearly visible, nothing obscuring them.
• Glasses — increasingly disallowed outright, and where permitted, no glare and no frames crossing the eyes.
• Head position and size — the head must occupy a specified proportion of the frame, which is the whole reason the crop step comes first.
• Recency — most authorities require a photo taken within the last six months.

None of these are fixable by resizing. If a photo is rejected after the dimensions are demonstrably correct, retake it rather than reprocessing it.

A checklist

1. Read the current specification from the issuing authority — dimensions, DPI or pixels, file size cap, accepted formats.
2. Convert to JPG if the source is HEIC or anything else.
3. Crop to the required aspect ratio with the head correctly positioned.
4. Resize to the exact pixel dimensions, aspect-ratio lock on.
5. Compress to fit the size cap, checking the background for blotching.
6. Check the photograph itself against the rules that have nothing to do with file handling — shadows, background, expression, glasses.

Every step runs in your browser on this site, so a passport photograph is never uploaded anywhere on its way to being the right size. Given what a passport photo is attached to elsewhere in your life, that is worth more than the convenience — and if you would rather verify it than trust it, the guide on checking whether a tool uploads your files shows you how.