Guides on getting a photo, a PDF or an upload accepted — the questions the tool pages deliberately leave alone.
The United States allows a natural smile. The UK, Canada, New Zealand and Germany want your mouth closed. Here is what each authority actually writes, why the rules disagree, and which parts of a photo a tool can check for you.
Two very different operations are both called compression. One cannot lose anything; the other loses something every time. Which one you are running decides what you are risking — and why zipping a folder of photos saves nothing.
300 DPI is a ratio, not a resolution — it means nothing until you know the print size. What the number does, what the DPI field in a file does not do, and when 300 DPI genuinely is a resolution.
You can wear your hair down for a US or UK passport photo, and neither country needs your ears visible. The real issue is that hair changes your chin-to-crown measurement.
There is no universal number. Visa portals want 40 KB to 1 MB, web images 100–300 KB, email under 5 MB, and print is measured in pixels instead. Here is each one, and how to hit it without wrecking the photo.
macOS has a one-click compressor in Preview that cannot aim at a size, and iOS has none at all — the Files app's Compress button makes a .zip. Here is what each device really does, and what to use when neither is enough.
Print quality is decided by pixels, not kilobytes. The formula is print size in inches × 300: a 4 × 6 needs 1200 × 1800 px, which any phone photo already has. File size only tells you whether it has been over-compressed.
Kilobytes are the second question — the format decides almost everything. Working targets: 10–50 KB for a website header, 1–10 KB for a favicon, under 20 KB for an email signature, and nothing at all for print.
Keep the images in an email signature under about 50 KB in total, and under 20 KB each. The reason is Gmail's 102 KB clipping threshold, not aesthetics — and it applies to every message you send, forever.
Most job portals cap a resume at 2 MB, some at 1 MB. A text-only resume should be well under 500 KB, so if yours is 6 MB something specific is wrong — and the usual fix quietly breaks the thing that reads it.
A printed passport photo has no file size. For uploads the number is set by the portal, and the windows are narrow: 40-120 KB for China, under 240 KB for the DS-160, up to 5 MB for the UAE. Here is the real list.
A ten-page text PDF should be 50-300 KB. If yours is 40 MB it is one of four things, and three of them are images. How to tell which in five seconds, and what each fix actually costs.
Upload errors come from three different limits: file weight, pixel dimensions, or file format. Here is how to tell which one stopped you, what the real numbers are on the forms people hit, and how to get under it.
The iPhone has saved photos as HEIC by default since 2017 because it halves the file size. Here is why so much software still rejects it, how to switch the camera back to JPG, and why converting makes the file bigger.
Most rejections come down to shadows, the crop, or a file that misses the upload spec. Here is what each authority actually checks, and what you can verify yourself before submitting.
"Photo upload service unavailable" and "photo does not meet requirements" are different problems with opposite fixes. How to tell which one you have, and the exact numbers CEAC checks.