Knitting needle sizes UK: mm, old UK and US chart

Read the millimetres first

Modern UK patterns and ball bands give needles in millimetres, and every band we checked for this page does. The old UK numbers only matter when you pick up a pattern from before the switch, or a tin of needles from a relative. The US numbers matter when you follow an American pattern.

The trap is that both other systems use plain numbers, and they run in opposite directions. A US 8 is 5mm. A UK 8 is 4mm. A US 10 is 6mm, while an old UK 10 is 3.25mm. If a pattern just says “size 8” and doesn’t name a country, check where it was published and look at the tension it asks for before you buy anything.

Where the chart comes from

The US column is the Craft Yarn Council’s Hooks & Needles table. The Council is the US industry body behind the standard sizes. The old UK column comes from two charts that we compared row by row: Sarah Maker’s knitting needle size chart and the conversion table in Wikipedia’s knitting needle article. They agree on every size from 1mm to 10mm, including the gaps.

The gaps are real. Neither chart gives an old UK number for 2.5mm or 3.5mm, and the Craft Yarn Council gives no US number for 3mm or 7mm. Below 2mm the charts skip a 16, but the Knitting & Crochet Guild’s notes on a 1954 Patons glove leaflet give size 16 as 1.6mm. The same notes make a useful point about fine needles in general: the leaflet’s 2-ply wool on size 16 needles “give a very small glove”, so the Guild suggests 3 ply on size 14 (2mm) for a medium adult hand.

We haven’t knitted any of the patterns on this page. Every size, tension and quantity is the maker’s, the archive’s or the Guild’s own, and each one is linked at the bottom.

Why the old UK numbers run backwards

Wikipedia’s knitting needle article says the old UK needle numbers were the Standard Wire Gauge sizes of the wire that metal needles were made from. It adds that the origin of the numbering is uncertain, but that it is thought to come from the number of ever finer dies the wire was drawn through. More draws made thinner wire and a higher number. According to Wikipedia’s Standard Wire Gauge article, the gauge was fixed by Order in Council on 23 August 1883 and became a legal standard on 1 March 1884.

We checked how closely today’s metric sizes follow that gauge, using the wire diameters in the Standard Wire Gauge table. From No. 17 down to No. 1, every metric equivalent in the chart sits within 0.13mm of the wire diameter for the same number. Gauge 10 is 3.251mm, almost exactly a 3.25mm needle. Gauge 8 is 4.064mm, and a No. 8 is 4mm. The fit loosens only at the thick end, Nos. 0 to 000: gauge 0 is 8.230mm against an 8mm needle, and gauge 000 is 9.449mm against 10mm. That’s our own comparison, not a published standard.

That may also explain the gaps. A 3.5mm needle falls between gauge 10 (3.251mm) and gauge 9 (3.658mm), and a 2.5mm needle between gauge 13 (2.337mm) and gauge 12 (2.642mm), so neither has a number of its own. Knitters checked unlabelled needles on a gauge plate. The Science Museum Group holds one, sold as a set with an “MP Handy Guide” row counter and dated 1945 to 1955, which its record says was used “to ascertain knitting needle diameter and as a short tape measure”.

Which needle the ball band asks for

We opened the makers’ own pages for Stylecraft and King Cole, and LoveCrafts’ listings for Paintbox Yarns, Hayfield and Sirdar, on 4 October 2026. The pattern is very consistent. Every DK on the list asks for 4mm. The 4 plys ask for 3.25mm, apart from Paintbox Yarns Cotton 4 ply at 3 to 3.25mm. The arans all say 5mm, and most chunkies say 6mm.

In old money, that’s a No. 10 for 4 ply, a No. 8 for DK, a No. 6 for aran and a No. 4 for most chunky. Super chunky starts at 10mm, the old No. 000, and Paintbox Yarns Simply Super Chunky goes up to 12mm, which has no old UK number at all.

The exceptions are in chunky. Hayfield Bonus Chunky asks for 6.5mm, and King Cole Comfort Chunky gives “8mm/US11 or 6mm/US10”. The Craft Yarn Council’s range for its Bulky category, which includes chunky, runs from 5.5 to 8mm, so both still sit inside it. For the other weights, the UK bands fall inside the Council’s ranges too: 3.75 to 4.5mm for DK and 4.5 to 5.5mm for aran.

The tension figure on the band is worth more than the needle size. A DK at 22 stitches to 10cm and an aran at 18 will not swap without changing the pattern, even if you change needles. Our UK yarn weights guide compares metres per 100g across 40 yarns if you need to match a substitute.

What a 1940s leaflet meant by No. 10

Patons & Baldwins pattern No. 2751, Men’s Service socks, gloves and mittens, is one of the 1940s leaflets for knitting for the Services that the University of Southampton’s Knitting Reference Library has put online. It asks for Beehive or Cycle Double Knitting, or Patons Super Wheeling 3-ply, and “Two No. 10 ‘Beehive’ Knitting Needles”, “measured by the Beehive gauge”. The tension is 7 stitches to the inch. Patons sized those needles on its own gauge, so 3.25mm is the modern chart equivalent of that No. 10, not a measurement of the needles Patons sold.

Seven stitches to the inch is 27.6 to 10cm. Today’s DK ball bands ask for 22 stitches on 4mm, and today’s 4 ply bands ask for 28 on 3.25mm. So that 1940s DK was knitted to roughly the tension of a modern 4 ply, about 25% more stitches across than a DK band suggests, on the same needle a 4 ply band names. Another Patons leaflet for the same DK, hospital stockings (No. 2753), asks for No. 6 needles and 6 stitches to the inch, about 23.6 to 10cm. Same yarn, four needle sizes apart, two different fabrics.

The Patons leaflets are firm about which comes first. Each one says the stated tension “must be obtained”, and that if you get more stitches to the inch, “needles a size coarser should be tried”. That advice still holds. The needle number on an old pattern is where you start, and the tension is what you aim for.

You can also see the switch to metric in these archives. The Guild’s notes on Patons leaflet E 1595, a 1978 Fair Isle slipover in Patons Fiona, give its tension on 4mm needles. A Loweth Wools aran sweater leaflet from the 1980s prints both systems side by side: “4mm (8) and 5mm (6) Milward needles”.

How to read a vintage British pattern

Start with the needles. Convert each number with the chart above. Garments often use two sizes, the smaller for ribbing. In the leaflets we read, the gap was two numbers: No. 12 and No. 10 for Lister’s Lavenda 4-ply, No. 11 and No. 9 for Patons’ “Hugh” jacket in Diana 4-ply. That’s 2.75mm and 3.25mm, or 3mm and 3.75mm.

Then convert the tension. Old patterns give stitches to the inch, and modern bands give stitches to 10cm. Multiply by 3.94 to compare: 7 to the inch is 27.6 to 10cm, 8 is 31.5. If the tension is given over 4 inches, as in the 1978 Patons leaflet’s 23 stitches, that works out at 22.6 to 10cm.

Next, the yarn. Old brand names such as Beehive, Lavenda or Mountain Maid won’t help you shop, and a ply number on an old leaflet didn’t always mean what it means now. Our history of yarn weight names follows that story. Choose a modern yarn whose ball band tension is close to the pattern’s, not one with the same name.

Last, the quantity. Old leaflets give ounces. One ounce is 28.35g, so the 6 oz of DK for the Service socks is about 170g. Weight only becomes length once you know the metres per 100g, and a 1940s leaflet doesn’t print that. Treat the grams as a rough guide, knit a tension square in your chosen yarn, and use the grams-to-metres converter or the yarn substitution calculator to turn the figures into balls.

Common questions

Sources and scope

• www.craftyarncouncil.com/standards/hooks-and-needles
• www.craftyarncouncil.com/standards/yarn-weight-system
• sarahmaker.com/knitting-needle-sizes/
• en.wikipedia.org/wiki/Knitting_needle
• en.wikipedia.org/wiki/Standard_wire_gauge
• collection.sciencemuseumgroup.org.uk/objects/co45164/mp-handy-guide-for-knitting-and-crochet-work
• archive.org/details/krl00536787
• archive.org/details/krl00536803
• archive.org/details/krl00536997
• archive.org/details/krl00536775
• archive.org/details/krl00536600
• kcguild.org.uk/pattern/pattern-downloads/patons-d-87-4d/
• kcguild.org.uk/pattern/pattern-downloads/royal-babys-fishermans-sweater/
• kcguild.org.uk/pattern/pattern-downloads/lister-a-914-4d/
• kcguild.org.uk/pattern/pattern-downloads/patons-c-923-4d/
• kcguild.org.uk/pattern/pattern-downloads/patons-c-893-4d/
• kcguild.org.uk/pattern/pattern-downloads/patons-e-1595-b/
• kcguild.org.uk/pattern/pattern-downloads/rowan-estonian-floral-jacket/
• www.stylecraft-yarns.co.uk/yarns/special-4-ply/
• www.stylecraft-yarns.co.uk/yarns/special-dk/
• www.stylecraft-yarns.co.uk/yarns/life-dk/
• www.stylecraft-yarns.co.uk/yarns/special-aran/
• www.stylecraft-yarns.co.uk/yarns/special-chunky/
• www.stylecraft-yarns.co.uk/yarns/special-xl/
• www.kingcole.com/product/big-value-baby-4ply/
• www.kingcole.com/product/merino-blend-4ply/
• www.kingcole.com/product/big-value-dk-50/
• www.kingcole.com/product/merino-blend-dk/
• www.kingcole.com/product/big-value-chunky/
• www.kingcole.com/product/comfort-chunky/
• www.kingcole.com/product/big-value-super-chunky/
• www.lovecrafts.com/en-gb/p/sirdar-country-classic-4-ply
• www.lovecrafts.com/en-gb/p/paintbox-yarns-cotton-4-ply
• www.lovecrafts.com/en-gb/p/paintbox-yarns-simply-dk
• www.lovecrafts.com/en-gb/p/hayfield-bonus-dk
• www.lovecrafts.com/en-gb/p/sirdar-snuggly-dk
• www.lovecrafts.com/en-gb/p/paintbox-yarns-simply-aran
• www.lovecrafts.com/en-gb/p/hayfield-bonus-aran-with-wool
• www.lovecrafts.com/en-gb/p/paintbox-yarns-simply-chunky
• www.lovecrafts.com/en-gb/p/hayfield-bonus-chunky
• www.lovecrafts.com/en-gb/p/paintbox-yarns-simply-super-chunky

Sources checked 4 October 2026. Label facts come from the linked references; worked purchase examples and arithmetic are our own illustrations.