StitchHow

Most knitting and crochet questions aren't really questions about taste or pattern-reading — they're arithmetic. "How much yarn do I need for this blanket?" "My gauge doesn't match the pattern — now what?" "How many stitches do I cast on for a hat that fits a 20-inch head?" These have real, computable answers, and StitchHow exists to give them to you directly, with the math shown, instead of burying them inside a forum thread or a vague rule of thumb.

What's here

StitchHow is five calculators and a reference library, built around the same core math throughout — no tool on this site invents a number that a different page contradicts, because every page pulls from the same tested calculation library.

• Yarn Quantity Estimator — figure out how much yarn a project needs, either from your gauge and stitch pattern or, more accurately, by weighing a swatch.
• Gauge Conversion Calculator — rescale a pattern's stitch and row counts to your own gauge when it doesn't match what's printed.
• Cast-On Calculator — turn a target circumference into a cast-on count that lands cleanly on your stitch pattern's own repeat, not just the nearest whole number.
• Stitch & Row Spacer — get the literal written instruction for an even decrease or increase row, remainder included, not just a stitch count.
• Needle & Hook Size Converter — knitting needles and crochet hooks, both, across every sizing system in common use.

Alongside the tools sits a reference library: yarn-weight guides, fibre profiles, a curated set of yarn substitutions, technique explainers for both crafts, a full abbreviation glossary, sizing charts, and a growing set of direct answers to the specific questions people actually search for.

Why this site exists

Ravelry and the big pattern databases already do community and pattern discovery well. Nobody has built the calculator layer with the same care — the actual arithmetic that sits underneath every project, done consistently, shown transparently, and never hidden behind an app download or a login wall. Every constant we use that isn't a third-party published standard is calibrated in the open on our methodology page, with the reference data we checked it against. If a number here looks wrong, you can see exactly how we got it and tell us.

Most-used calculators

Yarn quantity questions are, by a wide margin, the most common thing people search for before starting a project — closely followed by gauge mismatches and cast-on counts for hats and cowls. Those three tools are the ones we'd point a first-time visitor to first.

A note on accuracy

The gauge-based yarn estimate is a planning number, built from a calibrated model we document in full rather than a black box. When precision actually matters — you're down to your last skein and can't buy a matching dye lot — use the swatch-weighing mode instead, which needs no calibrated constant at all. It uses your actual yarn's actual density, directly.

Built for both crafts, not knitting with crochet as an afterthought

A lot of "yarn craft" calculators are visibly built knitting-first, with crochet support bolted on as a second thought — a single stockinette-shaped formula wearing a crochet label. StitchHow's yarn-quantity model treats single crochet, half double crochet, and double crochet as their own calibrated cases, not knit-stitch math with a different name, because the physical reality is genuinely different: crochet wraps yarn around the hook more times per stitch than knitting wraps it around a needle. Single and double crochet's constants are solved directly from real published projects, the same method used for the knitting side of the model; half double crochet, which had no trustworthy project of its own to solve from, is stated plainly as an interpolation rather than presented as independently sourced. Exactly how per-stitch yarn use trades off against a taller stitch needing fewer stitches per area is a genuinely open, honestly-documented question — not fully settled — and the full working, including where two source types disagree, is on the methodology page. The abbreviation glossary, technique library, and stitch-pattern reference are built the same way — as two complete crafts, not one craft with an appendix.

How to use this site

If you're planning a project before buying yarn, start with the Yarn Quantity Estimator in its gauge-based mode. Once you've got yarn in hand and a swatch made, switch that same tool to swatch-weighing mode for a more accurate number. If a pattern's stated gauge doesn't match your own swatch, the Gauge Conversion Calculator rescales its stitch and row counts before you cast on anything. And if you just have a specific, narrow question — "how many stitches for a 20-inch hat," "what needle is 4mm" — the Answers section is built to give you that one number directly, without a full article's worth of scrolling first.

FAQ

Do I need to create an account to use the calculators? No. Every tool runs entirely in your browser. Nothing you type is sent anywhere.

Are these calculators free? Yes, all of them, with no usage limit. StitchHow is supported by a mix of a small paid pattern-planning pack, an optional donation, and site advertising — see Support Us if you'd like to help keep it running.

Does this site cover both knitting and crochet? Yes — the yarn-quantity model, the abbreviation glossary, and the technique library each cover both crafts, and the calculators are explicit about which stitch pattern or craft you've selected before showing a result.

Where do the standard numbers (yarn weights, needle sizes) come from? The published Craft Yarn Council weight-category system and the standard needle/hook equivalence chart — both cited directly on the relevant pages, not something we invented. Full detail on the methodology page.