Methodology & Validation

How the calculator works

The forward calculator measures the area ratio between your target blanket and a representative swatch, then scales the yarn used by that swatch. It displays a low, likely, and high range rather than pretending handmade fabric has one exact consumption value.

The reverse mode starts with yarn you already have. It subtracts your visible reserve, divides usable yarn by measured yarn density, and turns the resulting area into dimensions using a square, baby, throw, twin, or custom proportion. Displayed maximum dimensions are rounded down.

What has been verified

• Forward and reverse area calculations, including conservative, likely, and optimistic ranges.
• Imperial/metric conversion and length/weight input paths.
• Planning reserves, skein rounding, maximum-size rounding, and custom proportions.
• Field-level validation, keyboard paths, clipboard output, responsive layout, and no mobile horizontal overflow.

These checks verify the implemented formulas and browser behavior. They do not prove that every yarn, stitch, hook, tension, border, or finishing method will match a result.

What has not been field-validated yet

SkeinWise does not currently have a sufficiently large real-project dataset comparing predictions with finished blanket consumption. We therefore do not claim a universal accuracy percentage or a fixed error rate. The worked numbers on this site are illustrative calculations unless explicitly labeled as a measured project.

Illustrative examples

Examples use hand-checkable numbers to demonstrate the arithmetic. They are not presented as customer projects, laboratory trials, or a representative sample of all crochet styles. If your swatch differs, your result should differ too.

Known limitations

Swatch dimensions and yarn consumption must describe the same whole piece of fabric. Measuring only an inner rectangle while weighing the entire swatch overstates yarn density. Exclude loose tails from yarn consumption. The selectable ±5%, ±10%, and ±20% ranges are planning assumptions, not measured confidence intervals or accuracy guarantees.

Plan borders, seams, joins, fringe, tassels, motifs, colour changes, complex stitch repeats, blocking or washing, tension drift, frogging, and scale error separately when your swatch does not include them. A scale-based estimate also depends on the label’s length-to-weight ratio and an accurate tare.

Corrections and updates

Last updated: September 7, 2026. If you find a mathematical, unit-conversion, accessibility, or wording issue, email hello@skeinwise.com with enough detail to reproduce it.