How We Verify Our Calculators
A knitting calculator is only as good as the numbers behind it. A wrong gauge assumption or a made-up yardage rate means running out of yarn three rows from the end. This page explains where our figures come from and how we check them.
The process
- ✓Every gauge, yardage and sizing figure is traced to a named source: the Craft Yarn Council Standard Yarn Weight System, ISO 6715 needle sizing, published knitting references such as Interweave and TKGA, and hand-worked test examples.Elizabeth Zimmermann’s Percentage System, and manufacturer ball-band data from brands such as DROPS and Lion Brand.
- ✓Every calculator is tested against hand-worked examples: we work the maths by hand from the source figures and compare the result to what the calculator returns.
- ✓In 2026 the whole site went through repeated independent re-checks, where each figure was re-derived from its source rather than assumed correct. When a re-check disagreed with the code, we fixed the code.
- ✓An automated test suite re-runs pinned worked examples across mobile and desktop browsers before every deployment, checking changes against known-good results before they go live.
- ✓Errors reported through the feedback buttons are investigated against the original source, fixed, and re-verified before going live.
- ✓When a source updates, such as a revised Craft Yarn Council chart, we review the calculators that depend on it.
Verified, not guaranteed
These calculators give planning estimates, not guarantees. Real yarn consumption varies with your personal tension, the stitch pattern, and the specific yarn, so always knit and measure a gauge swatch, buy 10-15% extra from the same dye lot, and confirm quantities with your yarn shop before a big purchase. For garment fit or pattern adjustments, the pattern designer’s instructions take precedence over any calculator.
Spotted an error?
Every calculator page has feedback buttons. If a figure looks wrong, tell us what you entered and what you expected: we investigate against the original source, fix anything that fails the check, and re-verify before the correction goes live. When a report shows a genuine error, the fix lands on the affected page itself, with a dated correction note where it matters.