Credits and licences

Last updated 2026-10-11

Our own code

The tools and page layouts are written for this site. The pages make no requests to other servers.

The calculators use published constants and textbook formulas, typed into our own code (no third-party tables or libraries are copied):

Paper and envelope sizes: ISO 216 (A series), ISO 269 (C and B envelope series, DL) and the US Letter / Half Letter sizes; US envelope sizes as used across the trade.
Box styles: generic geometry of common carton styles (regular slotted container, tray, roll-end tuck-front, reverse and straight tuck end); FEFCO codes are mentioned only as style names, no FEFCO drawings are used.
Board thicknesses (flute calipers) and common mailer, poly-mailer and sheet-label sizes: typical values sold by many suppliers, shown as a starting point.
Drawing: our own code writes the SVG and DXF (AutoCAD R12 lines) files; unit conversions use 1 in = 25.4 mm exactly.

None at present. If we add any library, font or data set, it will be listed here with its licence and a link (data/credits.json, rendered below).