Passport and Visa Photo Sizes, and Why They Keep Being Rejected
Official dimensions for the US, UK, Schengen and India, plus the head-height and file-size rules that actually cause rejections.
3 November 2026
Guides
Reference pages that answer a question on their own terms. Each one links to the tools that help, but you should not need a tool to get the answer.
Why Your PDF Is Too Big, and What Actually Controls the Size
Scan resolution, JPEG quality and pixel dimensions, ranked by how much each one actually costs you.
3 November 2026
KB vs KiB: Why 100 KB Means Two Different Things
The 2.4% discrepancy between the two definitions of a kilobyte, and why it makes upload forms reject files that look fine.
3 November 2026
JPG, PNG, WebP and AVIF: Which to Use and Why
What each format is actually good at, where each falls down, and the difference between a browser reading a format and writing one.
3 November 2026
DPI, PPI and Print Size: What 300 DPI Actually Means
Why an image has no physical size until it is printed, and how to convert between pixels and inches in either direction.
3 November 2026
Why Your Photo Uploads Sideways, and How EXIF Orientation Works
The orientation tag, why some software honours it and some ignores it, and why the real fix is to rewrite the pixels rather than the tag.
3 November 2026
Why Two Word Counters Give You Different Numbers
What counts as a word, why character counts disagree about emoji and accents, and how to stay safe against a limit you cannot test.
3 November 2026
Title Case: The Rules, and Where the Style Guides Disagree
The rules every guide agrees on, the length thresholds that separate AP from Chicago, and the 2024 change that moved them closer together.
3 November 2026
What these are for
Most of Celveri is tools, and a tool page can only tell you how to use the thing next to it. These pages are the other half: the background you need to know whether you are even solving the right problem.
They are written to be useful on their own. If you read one, understand why a form keeps rejecting your photograph, and fix it with software you already own, that is a success — the tools are a convenience, not the point.
Where a guide quotes a figure from an official source, it links to that source and shows when it was last checked. Where the published figures disagree with each other, it says so instead of picking one and sounding confident.