Yarn Weights Explained: UK 4ply, DK, Aran and Chunky vs US Names
Yarn weight describes how thick a yarn is, not how heavy the ball is. In the UK the main weights, from finest to thickest, are 2ply, 3ply, 4ply, double knitting (DK), aran, chunky and super chunky. In US terms these roughly match lace, fingering, light worsted, worsted, bulky and super bulky, and the Craft Yarn Council numbers them from 0 (lace) to 7 (jumbo).
What "ply" means today
Ply originally meant the number of strands twisted together to make the yarn, and in general more plies meant a thicker yarn. Today the names are best read as thickness categories. As the UK knitting publisher Simply Yarn explains in its yarn and needle conversion guide, a 4ply yarn might not have four plies at all: it could have more or fewer. What matters is the thickness, the recommended needle size and the tension printed on the ball band.
Two other naming habits are worth knowing:
- Australia and New Zealand often use ply numbers for every weight, so "8 ply" there is broadly the same as UK DK.
- US patterns use descriptive names (fingering, sport, worsted, bulky) and increasingly the numbered symbol from the Craft Yarn Council's standard.
UK vs US yarn weight conversion table
The CYC number, needle and hook ranges below come from the Craft Yarn Council's Standard Yarn Weight System. The council describes these as guidelines only: always follow the needle size and tension in your pattern and on the ball band.
| UK name | Common US name | CYC number | Needles (mm) | Hook (mm) | Typical uses |
|---|---|---|---|---|---|
| 1ply, 2ply (lace) | Lace, cobweb | 0 Lace | 1.5–2.25 | Steel 1.4–1.6, or 2.25 | Shawls, lace, christening wear |
| 4ply | Fingering, sock, baby | 1 Super Fine | 2.25–3.25 | 2.25–3.5 | Socks, baby clothes, fine jumpers, colourwork |
| (no common UK name) | Sport | 2 Fine | 3.25–3.75 | 3.5–4.5 | Light garments, baby items |
| Double knitting (DK) | Light worsted, DK | 3 Light | 3.75–4.5 | 4.5–5.5 | Jumpers, cardigans, toys, blankets |
| Aran | Worsted, aran | 4 Medium | 4.5–5.5 | 5.5–6.5 | Cabled jumpers, hats, blankets |
| Chunky | Bulky | 5 Bulky | 5.5–8 | 6.5–9 | Quick jumpers, hats, scarves, rugs |
| Super chunky | Super bulky | 6 Super Bulky | 8–12.75 | 9–15 | Throws, cowls, statement hats |
| Jumbo / roving | Jumbo | 7 Jumbo | 12.75 and larger | 15 and larger | Chunky throws, arm knitting |
A few notes on the table
- 3ply sits between 2ply and 4ply. It is mostly seen in vintage and baby patterns and has no exact US equivalent, so work from the tension given.
- Lace weight is usually knitted or crocheted on larger needles and hooks than the table suggests, to create an open, lacy fabric. Follow the pattern.
- Aran and worsted share CYC number 4, but they are not always identical: some aran yarns are slightly thicker than a typical US worsted, so swatch before substituting.
- Sport weight falls between 4ply and DK. A US pattern calling for sport yarn will need careful swatching if you substitute either.
Need the needle conversions too? Our knitting needle sizes guide converts old UK, metric and US sizes, and the craft conversion charts page puts yarn, needle and hook tables in one place.
The UK weights at a glance
4ply
A fine, versatile yarn for socks, baby garments and lightweight jumpers. UK ball bands for 4ply commonly suggest needles around 3–3.25 mm. It gives crisp stitch definition, which suits Fair Isle and other colourwork.
Double knitting (DK)
The workhorse of UK knitting and crochet, usually described as double the weight of 4ply. DK is often knitted on 4 mm needles and suits almost anything: adult jumpers, children's clothes, toys and blankets. Many beginner patterns are written for DK.
Aran
Thicker and warmer than DK, traditionally associated with cabled fisherman jumpers. Aran is commonly knitted on needles around 5 mm and grows faster than DK, which makes it a good next step for a first garment.
Chunky and super chunky
Chunky yarns knit up quickly on roughly 5.5–8 mm needles; super chunky uses 8 mm and above. They are ideal for hats, cowls and throws you want to finish in a weekend. They use more yarn by weight, so check the metres per ball as well as the price.
How to identify an unlabelled yarn
Charity-shop finds and leftover balls often lose their bands. Two simple methods help:
- Wraps per inch (WPI). Wrap the yarn snugly, without gaps or stretching, around a ruler or pencil for 2.5 cm (1 in), then count the wraps. Fewer wraps means a thicker yarn. Compare against a labelled yarn of known weight.
- Swatch and measure. Knit or crochet a square at least 10 cm (4 in) wide on the needle size you think suits it, then count the stitches over 10 cm and compare with the gauges on the Craft Yarn Council table. The CYC measures knitted gauge in stocking stitch and crochet gauge in US single crochet (UK double crochet).
Substituting yarn in a pattern
- Match the weight first, then the fibre: a cotton DK behaves differently from a wool DK, even at the same tension.
- Calculate by length, not by number of balls: total metres needed = metres per ball × balls in the pattern.
- Knit or crochet a tension square, wash it the way you will wash the finished item, then measure.
- Buy enough of the same dye lot to finish; shades can vary between lots.
You can browse yarn by weight in our knitting and crochet department. The catalogue is still being added, so check each listing's ball band details for weight, length and recommended needle size.
Quick checklist
- Thinnest to thickest in UK terms: 2ply, 3ply, 4ply, DK, aran, chunky, super chunky.
- 4ply ≈ US fingering (CYC 1); DK ≈ US light worsted (CYC 3); aran ≈ US worsted (CYC 4); chunky ≈ US bulky (CYC 5); super chunky ≈ US super bulky (CYC 6).
- "Ply" now describes thickness, not the number of strands.
- Table ranges are guidelines: the pattern and ball band take priority.
- Always swatch when substituting, and buy by metres rather than balls.
Crocheting with these yarns? Our guide to UK vs US crochet terms covers stitch names and hook sizes.
Frequently asked questions
What is UK DK yarn called in the US?
UK double knitting (DK) is usually called light worsted or DK in the US and is Craft Yarn Council weight 3 (Light). In Australia and New Zealand it is often called 8 ply.
Is aran the same as worsted?
Aran and worsted are both Craft Yarn Council weight 4 (Medium), but some aran yarns are slightly thicker than a typical US worsted. Knit or crochet a tension square before substituting one for the other.
What needle size should I use for 4ply yarn?
The Craft Yarn Council suggests 2.25–3.25 mm needles for weight 1 yarns such as 4ply, and many UK 4ply ball bands suggest around 3–3.25 mm. Always check the pattern and the ball band.
Does 4ply mean the yarn has four strands?
Not necessarily. Ply once meant the number of twisted strands, but today 4ply is a thickness category and a 4ply yarn may have more or fewer plies.
How can I tell the weight of a yarn with no label?
Wrap it snugly around a ruler for 2.5 cm (1 in) and count the wraps, comparing with a labelled yarn, or knit a 10 cm swatch and compare your stitch count with the Craft Yarn Council's gauge ranges.