Free tool
Knitting Needle Size Chart
Convert knitting needle sizes between metric millimetres, US numbers, and UK or Canadian numbers, and see the yarn weight each needle suits. The millimetre size is the reliable reference, since the US and UK systems number their needles in opposite directions.
| Metric | US | UK / Canada | Typical yarn |
|---|---|---|---|
| 2.0 mm | 0 | 14 | Lace, fingering |
| 2.25 mm | 1 | 13 | Fingering, sock |
| 2.5 mm | n/a | n/a | Fingering, sock |
| 2.75 mm | 2 | 12 | Sock, sport |
| 3.0 mm | n/a | 11 | Sock, sport |
| 3.25 mm | 3 | 10 | Sport |
| 3.5 mm | 4 | n/a | Sport, DK |
| 3.75 mm | 5 | 9 | DK |
| 4.0 mm | 6 | 8 | DK, light worsted |
| 4.5 mm | 7 | 7 | Worsted |
| 5.0 mm | 8 | 6 | Worsted |
| 5.5 mm | 9 | 5 | Worsted, aran |
| 6.0 mm | 10 | 4 | Aran |
| 6.5 mm | 10.5 | 3 | Aran, bulky |
| 7.0 mm | n/a | 2 | Bulky |
| 7.5 mm | n/a | 1 | Bulky |
| 8.0 mm | 11 | 0 | Bulky |
| 9.0 mm | 13 | 00 | Super bulky |
| 10.0 mm | 15 | 000 | Super bulky |
| 12.0 mm | 17 | n/a | Jumbo |
| 15.0 mm | 19 | n/a | Jumbo |
| 19.0 mm | 35 | n/a | Jumbo |
| 20.0 mm | 36 | n/a | Jumbo |
| 25.0 mm | 50 | n/a | Jumbo |
Sizes vary slightly between manufacturers, and a few in-between millimetre sizes have no exact US or UK number. When a pattern and your needles disagree, trust the metric millimetre size, and always confirm against a gauge swatch.
Choosing the right needle
The size chart gets you from one system to another, but the right needle for a project depends on your yarn and your tension. Our full guide to knitting needles covers types, materials, and lengths, and the circular needles guide explains cables and knitting in the round. To match a needle to a yarn, the yarn weight converter lines up the weight systems, and the gauge calculator turns your swatch into the right size.
Frequently asked questions
What is the most common knitting needle size?
The 5.0 mm needle, labeled US 8 and UK 6, is the everyday all-rounder. It pairs with worsted weight (UK aran) yarn, the most popular yarn for general knitting, so most beginner patterns and kits start there.
How do US and UK knitting needle sizes differ?
US needles use numbers that grow with the needle, so a higher US number is a thicker needle. The old UK and Canadian system runs the opposite way, so a higher UK number is a thinner needle. The metric millimetre size is the reliable common reference between the two.
What size needles do I use for worsted weight yarn?
Worsted weight yarn (UK aran, CYC 4) usually calls for a 4.5 mm to 5.5 mm needle, US 7 to 9. The yarn label gives a recommended size, but match your needle to a gauge swatch rather than to the label alone, since tension varies from knitter to knitter.
Are circular and double-pointed needle sizes the same as straight?
Yes. The size system is identical for straight, circular, and double-pointed needles, since it measures the needle diameter in millimetres. Only the form changes. A 5.0 mm needle is 5.0 mm whether it is straight, on a cable, or part of a double-pointed set.
Why do some millimetre sizes have no US or UK number?
A few in-between metric sizes, like 2.5 mm and 3.0 mm, sit between the standard US or UK numbers and have no exact match in that system, so they show as n/a. They are still sold by their millimetre size, which is why the millimetre is the size to trust.
Keep your needles and gauge with your project
CrochetZen saves the needle size and gauge for each project, tracks your rows, and spots dropped stitches with the AI camera. Free 3-day trial on iOS.