Japanese Knitting Needle Sizes Converted to US/UK/mm (Printable Chart)

If a Japanese pattern says 5号 (gō) needles, it means a needle that is 3.6 mm thick, not “size 5.” Japanese needle numbers run from 0号 = 2.1 mm up to 15号 = 6.6 mm in steps of 0.3 mm, and Clover, Tulip, and Hamanaka all use the same scale. Only a few of those sizes line up exactly with a US size, so the safest habit is to convert the number to millimeters first and shop from there. The chart below does that and tells you plainly when there is no match.

Checked against the makers’ own pages on 2026-10-17.

How Japanese needle numbers work

The Japanese word 号 (gō, “number” or “size”) is printed after the digit: 5号 is read “go-gō.” Clover’s own explainer for bamboo needles says the numbers go from 0号 (needle shaft 2.1 mm) to 15号 (6.6 mm) in 0.3 mm steps, and that anything thicker is called a jumbo needle and is labeled directly in millimeters.

That makes the Japanese system easy to do in your head: diameter in mm = 2.1 + 0.3 × (number). Check it against 8号: 2.1 + 2.4 = 4.5 mm. Unlike in the old UK system, a bigger number means a thicker needle, just as with US sizes.

Needles up to 15号 are the “numbered” range. After that you will see plain mm: 7 mm, 8 mm, 10 mm, and so on.

Quick chart: Japanese needle number to mm (print this one)

How to read it: “Nearest standard size” is the closest metric needle that appears in the Craft Yarn Council (CYC) table, with the gap in millimeters. Here a size counts as a match when the gap is 0.05 mm or less, a rough match at 0.1 mm, and “none close” beyond that. An em dash in the UK column means the old UK system has no number at that diameter.

Only 8号 and 13号 have an exact US match. 3号 is a standard 3.0 mm, but the Craft Yarn Council gives that diameter no US number. 2号, 4号, 7号, and 12号 are within 0.05 mm, close enough that most knitters would not notice. For the rest, a US needle may still work, but your gauge will shift slightly, so swatch (see below).

Notes for this table:

• A. 3号 = 3.0 mm. The CYC table has no US number for 3.0 mm (US 3 is 3.125 mm and 3.25 mm). UK retailer charts give 3.0 mm as US 2½ (A Yarn Story marks 2½ as “not an official US size”; KnitPro lists it as 2.5). Trust the millimeters here.
• B. UK column. The old UK numbers run backwards (a bigger number is a thinner needle) and have gaps. They come from retailer charts (A Yarn Story and KnitPro), not from a standards body. The UK column follows A Yarn Story; KnitPro’s chart agrees up to 8 mm but shows 0 (not 00 and 000) for 9 mm and 10 mm, so those two cells are disputed.
• C. 14号. Clover and Hamanaka make a 14号 (6.3 mm). Tulip’s bamboo circular-needle table goes from 13号 straight to 15号, so you may not find it in every brand.
• D. Metal circular needles. Tulip labels its metal circulars 0号, 1号, and 2号 as 2.00, 2.50, and 2.75 mm and notes these are “reference numbers” only. They are metric needles, not the 2.1/2.4/2.7 scale above.

Jumbo needles (labeled in mm)

Past 15号 the label is simply millimeters. Clover’s 2026 spec sheet lists jumbo needles at 7, 8, 9, 10, 12, and 15 mm; a 25 mm size appears in the sheet under a different product line. Tulip’s catalog lists 7, 8, and 9 mm. Hamanaka sells 7, 8, and 10 mm.

In English you will see the word “jumbo.” Clover calls its needles past 15号 ジャンボ針 (janbo-bari, “jumbo needles”), and ジャンボ (janbo) is a registered trademark of Clover (noted on Clover’s page for its jumbo crochet hooks). In the Hamanaka and Tulip listings cited here, thicker needles have no special name and are labeled by size alone, as in 7 mm.

The old UK numbers stop at 000 (10 mm) in the retailer charts cited here, so 12 mm and larger have no UK number.

What 号 means on a yarn label

Japanese yarn labels list the needle number they recommend (see our label guide). Hamanaka’s own Q&A gives these rules of thumb for matching yarn thickness to knitting needle numbers:

Hamanaka adds that the shape and thickness of the yarn can change the right choice. Treat this as a starting point.

How to use the chart

1. Find the number in your pattern (for example, “6号”).
2. Read off the millimeters (3.9 mm).
3. Pick the closest needle in your own system, or the same mm size if your needles are metric.
4. Swatch. Hamanaka’s own advice about its “standard gauge” is to knit a test swatch, check the gauge yourself, and adjust the needle number if needed. It also says to measure a larger swatch because the edges distort the count, and that cable and other crossing patterns often differ a lot from the printed gauge.

If your size falls on a “no match” row, go for the nearest metric needle you own or can buy, and fix the rest with the swatch.

Want to check a needle you already own? A needle gauge (a plate with holes marked in mm) tells you the diameter.

FAQ

What is a Japanese size 5 needle in US sizes? 5号 is 3.6 mm. CYC has no 3.6 mm entry. The nearest sizes are 3.5 mm (US 4) and 3.75 mm (US 5), so you may land on either one depending on how you knit. Swatch before committing.

Does 0号 mean a zero-millimeter needle? No. 0号 is the smallest numbered size, 2.1 mm. The number is a label, not a measurement.

Are Japanese needle sizes the same across brands? For the numbered range, the three makers compared here (Clover, Tulip, Hamanaka) agree to 0.1 mm. Differences show up at the edges: 14号 is missing from Tulip’s bamboo circular table, and Tulip’s metal circulars use reference numbers.

What if my pattern uses a number that has no US match? Use the millimeters. Choose the closest metric needle available to you and rely on your swatch. Gauge differs from knitter to knitter anyway.

Do the same numbers apply to crochet hooks? No. Hooks use a different system, with “/0” numbers and a separate lace-hook scale. See the hook size guide.

Reading a Japanese chart next? Start with how to read a Japanese knitting chart.

Sources

All pages below were opened on 2026-10-17.

• Clover, bamboo needle basics (0号 2.1 mm to 15号 6.6 mm, jumbo in mm): https://clover.co.jp/knitting/knitting_tool
• Clover, 2026年度 needle spec sheet (PDF): http://www.clover.co.jp/recipe/takumikikakus.pdf
• Clover, jumbo crochet hook page (「ジャンボ」 trademark note): https://clover.co.jp/seihin/jumboamure.html
• Tulip, bamboo and metal needle size table, buyer catalog p.51 (PDF, created Jan 2021): https://www.tulip-japan.co.jp/wp/wp-content/uploads/2014/02/21-03-10.pdf
• Hamanaka, bamboo needles, e.g. No.0 and No.15: https://hamanaka.jp/items/h250-100-0 and https://hamanaka.jp/items/h250-100-15
• Hamanaka, bamboo needle product list (jumbo mm sizes): https://hamanaka.jp/items/h250-110-7
• Hamanaka Q&A, yarn thickness to needle number: http://www.hamanaka.co.jp/qa/teami_q19.html
• Hamanaka Q&A, standard gauge and swatching: http://www.hamanaka.co.jp/qa/teami_q11.html
• Craft Yarn Council, Hooks & Needles standards (US sizes and mm): https://craftyarncouncil.com/standards/hooks-and-needles
• A Yarn Story, knitting needle conversion chart (old UK numbers, UK retailer): https://ayarnstory.co.uk/pages/knitting-needle-conversion-chart
• KnitPro, knitting needle sizes (old UK numbers, manufacturer blog): https://www.knitpro.eu/usa/blog/knitting-needle-sizes