Quilt Backing CalculatorEditorial Policy
This page states how the formulas and figures on Quilt Backing Calculator are chosen, checked, and corrected — so you never have to take a number on faith.
Sources before invention
Every calculator implements a published, attributable method. The diagonal backing calculator uses John Flynn's formula as he published it. The binding calculator uses Missouri Star Quilt Co.'s perimeter-plus-allowance method, with its one point of divergence (usable width) stated openly on the page. Batting packages are the standard retail sizes sold by The Warm Company and its competitors. Standard quilt and mattress dimensions are the commonly published chart values. Where respectable sources disagree, the calculator follows the source with the clearest worked examples, and the page says which source it followed.
How numbers are verified
Three layers of checking stand behind every figure. First, each calculator is tested in code against hand-computed cases, including published worked examples reproduced exactly — Flynn's Example 1 must come out at 88 inches because his sheet says 88 inches. Second, every worked example printed on the site is generated by the same code that runs the calculators, and the generated output is verified in QA against the built pages on every release — the examples and the tools are checked against each other rather than typed twice. Third, sources are re-read when a page is revised, not remembered.
Corrections
Errors get fixed, not defended. Any reader can file a report through the error report form or by email; reports are checked against the sources, and confirmed errors are corrected in the calculator and in any affected page content. If a correction changes a figure that other pages repeat, those pages are corrected in the same pass — the generated examples make this mechanical rather than a matter of memory. Start from the backing calculator on our homepage and follow any page's method notes to see this policy at work.
Independence
No fabric company, publisher or retailer pays for placement, influences a formula, or reviews content before publication. Methods are credited because credit is due, not because anyone asked. If advertising is introduced in future, it will be labeled as advertising and kept separate from the calculators' results, which will continue to be produced by the same tested code regardless.
Review
This policy and the site's methods are reviewed when sources change, when corrections reveal a pattern, and otherwise periodically. Last reviewed: 26 October 2026 by Ian Welkins.