The American system names stitches by their finished height, reflecting the number of yarn-overs before completing a stitch . In contrast, the British system labels stitches by counting the loops on the hook after the first pull-up. Historically, these divergent conventions developed independently in the 19th century, when crochet exploded in popularity across Europe and North America, and standardization bodies like the Craft Yarn Council later formalized US terms for packaging and patterns .

Because both systems reuse the same names—for example “double crochet” exists in both US and UK nomenclature but refers to different stitches—confusion is inevitable without a conversion reference . Fortunately, once you internalize that UK terms are one stitch “up” from US terms, you can decode any pattern: a UK double crochet equals a US single crochet, and a UK treble equals a US double crochet, and so on.

Key Stitch Name Differences

Above is the core conversion for basic stitches—memorizing this table will cover most projects.

For decreases and specialty stitches, the same one-level offset applies (e.g., US dc2tog = UK tr2tog) . Always check the pattern’s abbreviation list: many designers clearly state “US terms” or “UK terms” at the top to guide you .

Hook Size Notation

The US uses a lettering system (B, C, D, E, F, G, H, I, J, etc.) alongside fractional sizes, whereas the UK and Europe list hooks in metric millimeters (mm). For example, a US G hook corresponds roughly to a 4.5 mm UK hook, and a US I is about 5.5 mm .

Since a 0.25 mm difference often won’t noticeably alter gauge, it’s fine to select the closest available size when converting .

Tips for Seamless Conversion

Use a Conversion Chart: Keep a printed or digital chart handy—it’s the quickest way to translate both stitch names and hook sizes.

Note Pattern Origin: If a pattern mentions “single crochet” without specifying, assume US terms; if it uses “double crochet” contextually, check if it’s British .

Bookmark Reliable Resources: Sites like Shelley Husband Crochet and KnitPro provide clear printables and explanations for on-the-spot reference .

 Swatch and Measure: Especially when converting patterns, always make a gauge swatch—terminology shifts can subtly affect tension and size .

Quick Conversion Table

Final Thoughts

Switching between US and UK crochet terms is a small hurdle with big payoff: you gain access to an expansive world of patterns regardless of their origin.