Guides
Guides — How These Tools Actually Work
Short pieces that answer the question rather than perform the task. Each one explains how something actually works, what the trade-off is, and where the honest answer is to use something else.
Compress a PDF Without Uploading It
How PDF compression actually works, why most online compressors need your file on their server, and how to do it without sending it anywhere.
Rebar Weight: Where d²/162 Comes From
The formula behind every rebar chart, why the divisor is really 162.196, and the bar count that catches estimators out.
Concrete Grade Equivalents: M, C and psi
M25, C20/25 and 2900 psi describe the same concrete three ways — but the conversion charts get two things wrong, and some grades have no equivalent at all.
AWG to mm²: There Is No Exact Match
AWG never lands on a metric conductor size. Most gauges sit 12–17% away from the nearest one — and which way they miss changes as you go up the range.
Styling a QR Code Without Breaking It
How much of a QR code you can cover with a logo, why the three corner squares cannot be restyled, and the print size below which nothing scans.
Why Two Hijri Converters Give Different Dates
There is no single Hijri calendar. Umm al-Qura, the tabular and the civil calendars give different Gregorian dates, and the gap lands on Ramadan and Eid.