Japanese Knitting Needle Sizes (号) — Complete Conversion Guide
Japanese patterns use the 号 (gō) sizing system — a scale defined by the Japanese Industrial Standard (JIS) that doesn't align exactly with US, UK, or even metric sizes. Here's everything you need to convert.
Japanese patterns write sizes as 5号 or 8号 (read "5-gō" or "8-gō"). 号 means "number" or "size." Larger 号 numbers = larger needles.
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Japanese 号 to US, UK & Metric Conversion Chart
All standard Japanese needle sizes (JIS standard) with their millimeter measurements and nearest US and UK equivalents. A tilde (~) indicates the nearest standard size, not an exact match.
| Japanese (号) | Metric (mm) | US Size | UK Size | Yarn Weight |
|---|---|---|---|---|
| 0号 | 2 mm | US 0 | UK 14 | Fingering / Sock |
| 1号 | 2.1 mm | — | — | Fingering / Sock |
| 2号 | 2.4 mm | — | — | Fingering / Sock |
| 3号 | 2.7 mm | — | — | Fingering / Sock |
| 4号 | 3 mm | US 2.5 | UK 11 | Sport / DK |
| 5号 | 3.3 mm | — | — | Sport / DK |
| 6号 | 3.6 mm | — | — | DK / Worsted |
| 7号 | 3.9 mm | — | — | DK / Worsted |
| 8号 | 4.2 mm | — | — | DK / Worsted |
| 9号 | 4.5 mm | — | — | Worsted / Aran |
| 10号 | 5.1 mm | — | — | Worsted / Aran |
| 11号 | 5.4 mm | — | — | Worsted / Aran |
| 12号 | 5.7 mm | — | — | Bulky / Chunky |
| 13号 | 6 mm | — | — | Bulky / Chunky |
| 14号 | 6.3 mm | — | — | Bulky / Chunky |
| 15号 | 6.6 mm | — | — | Bulky / Chunky |
Understanding the Japanese 号 System
The Japanese needle sizing system (号, gō) was standardized under JIS (Japanese Industrial Standards) and is used across Japan, South Korea, Taiwan, and much of East and Southeast Asia. If you're working from a Japanese knitting book, magazine, or Ravelry pattern by a Japanese designer, you'll encounter this system.
How the 号 scale works
Japanese needle sizes start at 0号 (2.0 mm) and increase in steps of approximately 0.3 mm per size. This is a finer increment than US sizing — there are more distinct sizes in the Japanese scale below 5 mm, which reflects Japan's tradition of fine and lace knitting.
The standard JIS scale runs from 0号 to 15号 (6.6 mm). Above this, Japanese patterns use metric (mm) sizing, just as other countries do for very large needles.
Why Japanese sizes don't match US or metric exactly
The 0.3 mm increment means Japanese needle sizes often fall between standard US and metric sizes. A Japanese 7号 is 3.9 mm — there is no US or metric needle that is exactly 3.9 mm. The nearest US size is US 5 (3.75 mm) or US 6 (4.0 mm), — choose whichever matches your pattern's gauge.
This is not a problem unique to Japanese needles — slight size differences between systems are normal. The golden rule: always knit a gauge swatch and adjust needle size until your stitch count matches, regardless of what the label says.
Reading Japanese knitting patterns
Japanese knitting books (particularly those from publishers like Nihon Vogue, Ondori, and Keito Dama) are widely imported and shared on Ravelry. They list needle sizes as, for example, "棒針5号" (bō-bari 5-gō, meaning "knitting needle size 5"). The character 棒針 (bō-bari) means "straight knitting needle" and 輪針 (rin-bari) means "circular needle."
Japanese Needles and Lace Knitting
Japan has a particularly strong tradition of fine lace knitting, which is reflected in the 号 system's finer gradations at smaller sizes. Japanese lace knitting patterns frequently call for sizes 0号–4号 (2.0–3.0 mm) — sizes rarely used outside of sock or lace knitting in Western patterns. If you're working from a Japanese lace pattern, you may need to source needles specifically in those sizes.