“How many pixels” has two completely different answers, and mixing them up is how photos get rejected. Some specs fix the pixels directly — the portal checks the numbers at upload. Others give only a print size in millimetres, where the pixel count depends on the resolution you print at. Here’s both tables.

Specs that fix the pixels

When the portal publishes pixel dimensions, that number is the requirement — dpi is irrelevant.

Document	Pixel spec	File limit
US passport / visa (digital channels)	600–1200 px square	≤240 KB JPEG
US DV lottery	exactly 600×600 px	≤240 KB JPEG
UK passport (online)	≥600×750 px	50 KB – 10 MB
India passport	exactly 630×810 px	≤250 KB JPEG
India e-visa	≥350×350 px, square	10 KB – 1 MB
China visa (COVA portal)	354–420 × 472–560 px — some centre forms cap at 354×472 px	~40–120 KB
New Zealand passport (online)	900–4500 × 1200–6000 px (4:3 portrait)	250 KB – 5 MB

Two details worth noting: “exactly” is literal — India’s 630×810 rejects 629×810 before any other check runs. And windows have upper bounds — a 4000-px phone photo fails the US 1200 px maximum, so bigger is not better.

Specs that give millimetres — convert at your dpi

When the spec is a print size, the pixel count is mm ÷ 25.4 × dpi. At 300 dpi (the lab standard) and 600 dpi (maximum-quality prints):

Print spec	@300 dpi	@600 dpi	Used by
35×45 mm	413×531 px	827×1063 px	ICAO family — Schengen, India, Japan, NZ, Germany, France
2×2 in (51×51 mm)	602×602 px	1205×1205 px	US paper photo
33×48 mm	390×567 px	780×1134 px	China paper photo
35×45 mm	413×531 px	827×1063 px	UK paper photo (GOV.UK writes it 45 high × 35 wide — same rectangle)
50×70 mm	591×827 px	1181×1654 px	Canada; Brazil 5×7 cm (under-5s)

Notice none of these 300-dpi conversions matches any portal’s fixed window — 413×531 px is not acceptable for India’s 630×810 upload even though both describe 35×45 mm. The print math and the portal spec are separate requirements; a photo has to satisfy whichever channel you’re using.

Try the converter

What about the dpi field?

If a form or a lab asks for a dpi value rather than pixel dimensions, write 300 — the lab standard every print spec assumes. The field is pure metadata: it tells a printer how densely to pack the pixels, and changing it alters nothing about the file’s pixel dimensions. A “600 dpi” file with 413×531 px prints at exactly the same quality as a “300 dpi” file with the same pixels — it would just print smaller. Upload portals ignore the field entirely; only the pixel counts in the tables above are checked.

Which number to aim for

Read the spec card for your document: if it lists pixels, that’s the target (and “exactly” means exactly). If it lists only millimetres — as print-first countries like Canada and Japan do — convert at 300 dpi for a lab print or crop to the portal’s own window for an online form. China’s pair is the cautionary case: paper wants 33×48 mm while the COVA portal wants a 3:4 window the paper size doesn’t convert into.

Related: how to read a spec sheet · why photos get rejected · India’s 630×810 spec.

Frequently asked questions

How many pixels is a 35×45 mm passport photo?

At the lab-standard 300 dpi, 35×45 mm is 413×531 px; at 600 dpi it's 827×1063 px. But when a portal gives an exact figure — like India's 630×810 px — that number is the requirement, not a conversion; submit exactly those pixels.

Is 600×600 px enough for a US visa or passport photo?

600×600 px is the *minimum* of the 600–1200 px square window — it passes the dimension check. It's also the exact size the DV lottery requires. For the regular passport/visa upload, anywhere in 600–1200 px is acceptable as long as the file stays under 240 KB.

Does dpi matter for an online upload?

No. Portals check pixel dimensions and file bytes; the dpi field in the file's metadata is ignored. dpi only decides how large the photo physically prints — it never appears in an upload rule.

Why did the portal reject my photo at the 'right' pixel size?

Pixel dimensions are only one check — the file-size window (≤240 KB for the US, 50 KB–10 MB for the UK) and the head-height band reject just as many uploads. And 'exactly' specs are literal: 629×810 px fails India's dimension check before anything else is read.