US 9 Knitting Needle Size
US 9 is the needle most aran-weight patterns call for. It knits up faster than worsted on US 8 and produces a warm, substantial fabric without going full chunky.
5.5 mm · UK 5 · Japanese ~11号 · Yarn: Aran / Heavy Worsted
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Open Needle Size Converter →Enter US 9 — or any other size — to see all equivalents side by side.
US 9 in Every Sizing System
| System | Size | Notes |
|---|---|---|
| Metric | 5.5 mm | Exact — marked on most modern needles |
| US | 9 | American standard |
| UK / Australian | 5 | UK 9 ≠ US 9 |
| Japanese | ~11号 | 11号 = 5.4mm — very close |
| Yarn weight | Aran (#5 Bulky) | Standard gauge: 16–18 sts per 4" |
About US 9
Aran weight sits between worsted and bulky — heavier than the yarns you'd use on a US 8, but not as thick as what a US 10 or 11 is designed for. It's a popular weight for cable knits, where the extra yarn thickness makes the cables pop.
US 9 is also the needle a lot of knitters reach for when they want to knit worsted yarn on the looser side — for a drapier fabric or a more relaxed gauge. If a worsted pattern says "US 8–10," US 9 is the middle ground.
Aran weight vs. worsted: what's the difference?
Aran weight (sometimes called "heavy worsted" on American yarn labels) is a bit thicker than standard worsted. Worsted is typically knit on US 7–9; aran tends to call for US 8–10. The line between them is blurry enough that checking the yarn label's needle recommendation matters more than the weight name.
What to Knit with US 9 Needles
Cable knits — aran weight was practically designed for cables. Irish fisherman sweaters, cabled cowls, and Aran-style blankets all traditionally use this weight and needle range.
Sweaters and cardigans — knits up faster than worsted while still giving structure. Good for textured stitch patterns.
Blankets — aran on US 9 is a manageable combination for a throw or lap blanket. Not as fast as bulky, but the finished fabric is less stiff.
Hats and cowls — a chunky hat on US 9 takes an evening or two. The fabric is warm and well-structured.