Guides
Guides to the jobs people bring to ToolboxHere
Written by the person who builds the tools: what the figures mean, what goes wrong, and what to check before you send a file to a form, an office or a client. Every figure names its source.
ImagesHow to compress a photo to 100 KB, 50 KB or 20 KB without ruining itWhy phone photos are 3 to 8 MB, which of pixels, quality and format to change first, and how to get under 100 KB, 50 KB or 20 KB with the photo still sharp.6 min read · Updated 2 October 2026DocumentsPDF to Word: why the converted file looks wrong, and how to get a clean .docxA PDF holds letters at positions, not paragraphs, so converters guess. What goes wrong with scans, fonts, tables and columns, and how to get a clean file.6 min read · Updated 2 October 2026PhotosPassport photo sizes by country, and the rules that get photos rejectedPassport and visa photo sizes for the US, UK, Schengen, Canada, China, Saudi Arabia, Qatar and India, in mm and pixels, and the rules that get photos rejected.7 min read · Updated 2 October 2026UtilitiesQR codes that scan every time: size, error correction and logosHow big to print a QR code for its scanning distance, what error-correction levels L, M, Q and H do, how much a logo may cover, and what to put in the code.6 min read · Updated 2 October 2026IslamicWhy two apps show different prayer times, and which one to trustTwo apps in the same city can show Fajr or Isha minutes apart: the calculation methods, the Asr rule, rounding, coordinates, and which timetable to trust.6 min read · Updated 2 October 2026
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