Knitting Tool
Needle Size Conversion
Complete international conversion chart and lookup between Metric (mm), US, and UK needle sizes.
How to use the chart
- 1 Identify pattern sizing
Check whether the pattern lists sizes in mm, US, or UK numbers.
- 2 Browse or search
Scan the complete table or use the search tab to convert directly.
- 3 Swatch to confirm
Always verify your needle choice with a swatch to meet pattern gauge.
Needle Sizes
Needle Size Converter
Easily convert knitting needle sizes between metric mm, US sizes, and UK sizes. Use our handy conversion chart to find the right needle for your project.
| mm | US | UK |
|---|---|---|
| 1.5 | 000 | 16 |
| 1.75 | 00 | 15 |
| 2 | 0 | 14 |
| 2.25 | 1 | 13 |
| 2.5 | 1.5 | – |
| 2.75 | 2 | 12 |
| 3 | 2.5 | 11 |
| 3.25 | 3 | 10 |
| 3.5 | 4 | – |
| 3.75 | 5 | 9 |
| 4 | 6 | 8 |
| 4.5 | 7 | 7 |
| 5 | 8 | 6 |
| 5.5 | 9 | 5 |
| 6 | 10 | 4 |
| 6.5 | 10½ | 3 |
| 7 | – | 2 |
| 7.5 | – | 1 |
| 8 | 11 | 0 |
| 9 | 13 | 00 |
| 10 | 15 | 000 |
| 11 | – | – |
| 12 | – | – |
| 12.75 | 17 | – |
| 15 | 19 | – |
| 19 | 35 | – |
| 20 | 36 | – |
| 25 | 50 | – |
| 35 | 70 | – |
A Norwegian version of this page is available on Strikketips.no
Why you need a needle size chart
US patterns give needle sizes as US numbers, metric patterns in millimeters, and older British patterns in their own numbered scale. The numbers don't line up: "size 8" is 5 mm in the US column of our table and 4 mm in the UK column. Converting before you buy saves a swatch on the wrong needles.
US needle sizes
The US scale in our table runs from US 000 (1.5 mm) to US 70 (35 mm). Higher numbers are thicker needles. Every millimeter-to-US pair in the table follows the Craft Yarn Council's knitting needle chart, except 6 rows that CYC either doesn't list or gives no US number for — we include them because they are sizes you can buy: 2.5 mm, 3 mm, 7.5 mm, 11 mm, 12 mm, 20 mm. For 3 mm, CYC gives no US number at all; US 2.5 is the size we list it under.
Which size a project needs comes from the yarn: best knitting needles has the Craft Yarn Council's needle range for every yarn weight category.
Metric sizes (mm)
Metric sizing is simply the needle's diameter in millimeters: a 4 mm needle is 4 mm across. When a pattern gives both a US number and millimeters, the millimeters are the unambiguous one.
UK sizes
Older British patterns use a numbered scale that runs the opposite way: in our table, higher UK numbers are thinner needles — UK 14 is 2 mm and UK 000 is 10 mm. Treat that column with care. The Craft Yarn Council publishes no UK numbers, no standards body maintains the scale today, and we have not found a published source to confirm it against. Where a UK pattern also gives millimeters, go by the millimeters. Our US/UK pattern glossary covers the other words that change between the two.
A pattern's needle size is a starting point. If your swatch has too many stitches, go up a size; too few, go down one — and swatch again. There is no fixed rule for how far one size moves your gauge; see all about knitting gauge.
Japanese needle sizes (JIS)
Japanese patterns number needles in steps of 0.3 mm, from JIS 0 (2.1 mm) to JIS 15 (6.6 mm). We haven't found a standards body that publishes this scale the way CYC publishes the US one, so read it as our own summary. Next to the nearest size in our table:
- JIS 0: 2.1 mm (~US 0)
- JIS 3: 3.0 mm (~US 2.5)
- JIS 6: 3.9 mm (~US 6 / 4 mm)
- JIS 10: 5.1 mm (~US 8 / 5 mm)
- JIS 15: 6.6 mm (~US 10.5 / 6.5 mm)
What is the difference between US needle sizes and millimeters?
Millimeters give the needle's actual diameter. US sizes are a numbered scale on top of it: the number goes up as the needle gets thicker, but the steps are not even, so the only way to convert is a table like the one on this page.
How can I tell what needle size I have if the marking has worn off?
Use a knitting needle gauge ruler — a tool with precisely calibrated holes labeled in millimeters and US sizes. Push your needle into the smallest hole it fits snugly through.
Are US and UK knitting needle sizes the same?
No. In US sizing, higher numbers mean thicker needles (US 1 = 2.25 mm, US 10 = 6 mm). The traditional UK scale in our table runs the other way (UK 14 = 2 mm, UK 4 = 6 mm) — but no standards body publishes the UK scale today, and we have not been able to confirm it against a published source. When a pattern gives millimeters as well, use those.
The mm-to-US conversions follow the Craft Yarn Council's knitting needle size chart. The rows CYC does not list, or gives no US size for, are named in the section on US sizes above; they are included because those are sizes you can buy. The UK column is the traditional British scale, which CYC does not publish and no standards body maintains today. US and UK numbering are separate systems, not two names for one scale, so a few sizes have no exact counterpart.