KnitCalcs
Yarn Weight Converter — UK, US & Australian Systems
Convert between yarn weight naming systems. See equivalent names, needle sizes, gauge ranges, and meterage for any yarn weight.
How We Calculate This
This converter provides the equivalent names across yarn weight systems used in the UK, US, Australia, and by the Craft Yarn Council. It also shows the recommended needle sizes, typical gauge range, and expected meterage per 100g.
How it works
Yarn weight categories are standardised groupings based on the thickness of the yarn strand. While exact boundaries vary slightly between systems, the categories map to specific gauge ranges and needle sizes that are consistent worldwide.
- UK system: Uses names (4-ply, DK, Aran, Chunky) and ply numbers
- US system: Uses names (Fingering, Sport, Worsted, Bulky)
- Australian system: Primarily uses ply numbers (4 ply, 8 ply, etc.)
- Craft Yarn Council: Uses numbered categories (0-7)
Advanced Options let you adjust the typical meterage for denser or lighter fibre types and apply a WPI variance for yarns with tighter or looser twist.
Frequently Asked Questions
DK (Double Knitting) is the UK term for a medium-light weight yarn, typically knit on 3.75-4.5mm needles at 21-24 stitches per 10cm. Worsted is a US term for a slightly heavier yarn, knit on 4.5-5.5mm needles at 16-20 stitches per 10cm. Worsted is closer to UK aran weight. The terms are often confused because "worsted" can also refer to a spinning method.
Ply originally referred to the number of strands twisted together to make the yarn. However, modern ply counts are standardised labels rather than literal strand counts: 4-ply means fingering weight, 8-ply means DK, 10-ply means aran/worsted, and 12-ply means chunky. A yarn labelled 4-ply could actually have 2, 3, or 6 physical plies.
WPI stands for Wraps Per Inch. To measure it, wrap yarn around a ruler or pencil snugly (not stretched, not loose) and count how many wraps fit in one inch (2.54cm). This gives you an objective measurement of yarn thickness regardless of what the label says. WPI is especially useful when the ball band is missing or when assessing handspun yarn.
Related Calculators
Yarn Meterage Calculator
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DK Equivalent Yarn Calculator
Calculate adjustments when substituting one yarn weight for another in a pattern.
Yarn Yardage Calculator
Calculate total yarn yardage needed for any project based on dimensions and gauge.
Yarn Substitution Calculator
Calculate how many balls of a substitute yarn you need to match the original.
Yarn Ball Winder Calculator
Estimate centre-pull ball dimensions and yardage from skein specifications.
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Last updated: February 2026
All calculations are estimates based on standard yarn weights and gauge. Results may vary with individual tension, yarn brand, and needle size.