Everything here is either computed from a stated formula or taken from a named source. This page says which, and it says plainly what could not be verified.
Standards
- ISO 216 — paper sizes. The iterative rounding rule is confirmed three ways: Markus Kuhn's reference page and implementation, and by reproducing all 33 A, B and C dimensions from the seeds. The standard itself is paywalled and is not quoted.
- ISO 217 — RA and SRA press sheets.
- ISO 12647-2 — offset. Screen ruling 48–80 cm⁻¹ (120–200 lpi); platesetter resolution sufficient for at least 150 tone steps. Paywalled; figures cross-checked against ECI and Fogra documentation.
- ISO 12647-3 — newsprint, 40 ± 2 cm⁻¹, which is about 102 lpi. This contradicts the 85 lpi figure in general circulation.
- ISO 16762 — process control for binding and finishing; tolerances accumulate across successive processes.
- International Yard and Pound Agreement, 1959 — the inch is exactly 25.4 mm. NIST.
Colour
- ICC Profile Registry — total ink, maximum black and black generation per profile. This is the primary source for the ink-limit table and it is free.
- Lightness values measured from FOGRA51 characterisation data.
Print-on-demand
- KDP — spine multipliers, published here. KDP publishes no hardcover multiplier.
- Lulu — (pages ÷ 444) + 0.06 in, from the Book Creation Guide. Hardcover is a lookup table, not a formula.
- IngramSpark — 300 ppi with a 175 lpi screen; 600 ppi for one-bit line art; text at 24 pt and below in 100% black. IngramSpark publishes no spine formula.
Bleed and safe margin
Each of the twenty printers in that table was read from its own published spec page on 2026-08-23, with the per-edge or total convention recorded as they state it.
What could not be verified
- Creep and shingling. No printer checked publishes a numeric allowance. There is no creep calculator on this site for that reason.
- A quality factor for stochastic screening. ISO specifies FM screening by dot size, 20–40 μm, and not by any lpi equivalent. The commonly repeated "FM needs 300–400 ppi" could not be traced to a primary source, so it is not stated here as fact.
- Fold shortening. Two to four millimetres per tucked panel is trade practice, not a published specification. The fold calculator says so on its own page.
- Digital and toner ink limits. No press vendor publishes a TAC figure for toner devices.