Needle Size Chart: mm, US & UK
Convert between millimetres, US and UK needle sizes
| mm | US | UK | Yarn Weight |
|---|---|---|---|
| 1.5 | 000 | — | Lace (0) |
| 1.75 | 00 | — | Lace (0) |
| 2.0 | 0 | 14 | Fingering (1) |
| 2.25 | 1 | 13 | Fingering (1) |
| 2.5 | 1.5 | 12 | Fingering (1) |
| 2.75 | 2 | 12 | Fingering (1) |
| 3.0 | 2.5 | 11 | Sport (2) |
| 3.25 | 3 | 10 | Sport (2) |
| 3.5 | 4 | — | DK (3) |
| 3.75 | 5 | 9 | DK (3) |
| 4.0 | 6 | 8 | DK (3) |
| 4.5 | 7 | 7 | Worsted (4) |
| 5.0 | 8 | 6 | Worsted (4) |
| 5.5 | 9 | 5 | Bulky (5) |
| 6.0 | 10 | 4 | Bulky (5) |
| 6.5 | 10.5 | 3 | Bulky (5) |
| 8.0 | 11 | 0 | Super Bulky (6) |
| 9.0 | 13 | 00 | Super Bulky (6) |
| 10.0 | 15 | 000 | Super Bulky (6) |
| 12.0 | 17 | — | Jumbo (7) |
| 15.0 | 19 | — | Jumbo (7) |
| 25.0 | 50 | — | Jumbo (7) |
All values are guidelines, the yarn label is always the most reliable source.
Three systems, one needle — that's the core of needle size confusion. Millimetres are the international standard and appear on almost every modern yarn label. US numbers go up as needles get thicker; UK numbers run the opposite direction. When following a UK or US pattern with metric needles, just look at the mm column — it always translates.
The needle size on a yarn label is a starting point, not a rule. Your gauge swatch decides. Always knit a 4×4 cm swatch and compare it to your pattern before committing — going up or down half a millimetre can make all the difference.
For sock yarn (Fingering, CYC 1), many knitters go slightly smaller than the label recommends to create a denser, more durable fabric. 2.25 mm instead of 2.5 mm has a noticeable impact on how long your socks last.
Looking for a substitute for a specific project?
→ Find a yarn substituteFrequently Asked Questions
What is US needle size 7 in mm?
US 7 equals 4.5 mm. US numbers go up as needles get thicker; UK numbers go the other way, a common source of confusion when following patterns from different countries.
Why do UK and US needle sizes use different numbers?
The two systems were developed independently. UK numbers run backwards: a low UK number means a thick needle. Today millimetres are the international standard, German yarn labels almost always use mm.
What needle size do I need for sock yarn?
Sock yarn (Fingering weight) is typically knitted on 2–2.5 mm needles, which is US 0–1.5 or UK 14–13. Many knitters prefer 2.25 mm for a firm, durable fabric.
Do I have to use the exact recommended needle size?
No, the needle size on the label is a recommendation. What matters is your gauge swatch. Always knit one first and adjust your needle size until your tension matches the pattern.