SkeinMath

Knitting needle size chart

Published October 13, 2026.

Knitting needles are measured by their diameter. The millimeter size is the exact measurement; US numbers are labels, and brands don’t always use them the same way. When a pattern and a package disagree, go by the millimeters.

Needle sizes: millimeters to US

Millimeters US size
1.5 mm 000
1.75 mm 00
2 mm 0
2.25 mm 1
2.75 mm 2
3 mm none
3.125 mm 3
3.25 mm 3
3.5 mm 4
3.75 mm 5
4 mm 6
4.25 mm 6
4.5 mm 7
5 mm 8
5.25 mm 9
5.5 mm 9
5.75 mm 10
6 mm 10
6.5 mm 10½
7 mm none
8 mm 11
9 mm 13
10 mm 15
12.5 mm 17
12.75 mm 17
15 mm 19
19 mm 35
25 mm 50
35 mm 70

Things to watch

  • One US number, two metric sizes. US 3, 6, 9, 10 and 17 each appear twice in the chart, a quarter of a millimeter or less apart. If gauge matters, buy by millimeters.
  • Some metric sizes have no US number. 3 mm and 7 mm needles exist but have no US label in the chart.
  • Gauge decides, not the needle. A pattern’s needle size is a starting point. If your swatch has more stitches per 4 inches than the pattern, go up a size; if it has fewer, go down. The gauge calculator shows how far off you are.

To see which needle sizes go with each yarn thickness, use the yarn weight chart.

Questions

What size is a US 8 knitting needle in mm?

5 mm.

Is a US 10 needle 5.75 mm or 6 mm?

Both are sold as US 10. Check the millimeter size on the package, which is the exact measurement.

Is there a US size for a 3 mm or 7 mm needle?

No. The Craft Yarn Council chart lists 3 mm and 7 mm needles without a US number, so look for them by their metric size.

Sources

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