5.5 mm knitting needle
5.5 mm
US 9 · UK 5 · Aran
What this size is for
Aran sweaters and heavier accessories. Fast enough to finish a garment and fine enough to hold a cable pattern.
In each scale
| Diameter | 5.5 mm |
| US size | 9 |
| UK / Canadian size | 5 |
| Yarn weight | Aran |
A US 9 and a UK 9 are not the same needle. This one is 5.5 mm; the British 9 is 3.75 mm. Buy by millimetre wherever the pattern allows it.
Nearby sizes
| mm | US | UK | Yarn |
|---|---|---|---|
| 4 | 6 | 8 | DK |
| 4.5 | 7 | 7 | DK to worsted |
| 5 | 8 | 6 | Worsted, aran |
| 5.5 | 9 | 5 | Aran |
| 6 | 10 | 4 | Aran to chunky |
| 6.5 | 10.5 | 3 | Chunky |
| 7 | — | 2 | Chunky |
Frequently asked questions
What is a 5.5 mm knitting needle in US and UK sizes?
US 9 and UK 5. The millimetre figure is the actual diameter and the only one that means the same thing everywhere.
Is a US 9 the same as a UK 9?
No. A US 9 is 5.5 mm; a UK 9 is 3.75 mm. The scales run in opposite directions — American numbers grow with the needle and British ones shrink — so the same number is two different needles.
What yarn suits a 5.5 mm needle?
Aran. Aran sweaters and heavier accessories. Fast enough to finish a garment and fine enough to hold a cable pattern.
Why do the two scales run in opposite directions?
The British scale counts down from the thickest wire in a gauge, in the same way a wire gauge does — more drawing operations, higher number, thinner. The American scale simply counts up from the finest needle. Neither is wrong; they were never designed to be compared, and the only size where the numbers coincide is 4.5 mm, which is size 7 in both.