Knitting needle sizes: conversion chart (US, UK & mm)
Knitting needle sizes are measured three ways, metric (millimetres), US numbers and old UK/Imperial numbers. The chart below converts all three, so you can translate any pattern or needle no matter where it was written.
By Sofia AkramiKnyt Co-founder and editor
Needle size conversion chart
| Metric (mm) | US size | UK / Canada (old Imperial) |
|---|---|---|
| 2.0 mm | 0 | 14 |
| 2.25 mm | 1 | 13 |
| 2.50 mm | 1.5 | - |
| 2.75 mm | 2 | 12 |
| 3.0 mm | 2.5 | 11 |
| 3.25 mm | 3 | 10 |
| 3.50 mm | 4 | - |
| 3.75 mm | 5 | 9 |
| 4.0 mm | 6 | 8 |
| 4.5 mm | 7 | 7 |
| 5.0 mm | 8 | 6 |
| 5.5 mm | 9 | 5 |
| 6.0 mm | 10 | 4 |
| 6.5 mm | 10.5 | 3 |
| 7.0 mm | - | 2 |
| 7.5 mm | - | 1 |
| 8.0 mm | 11 | 0 |
| 9.0 mm | 13 | 00 |
| 10.0 mm | 15 | 000 |
| 12.75 mm | 17 | - |
| 15.0 mm | 19 | - |
| 19.0 mm | 35 | - |
| 25.0 mm | 50 | - |
Why metric is the size that matters
US and UK needle numbers were never perfectly standardised, and they run in opposite directions; in the US a bigger number means a bigger needle, but in the old UK system a bigger number means a smaller needle. The millimetre measurement is a direct physical measurement of the needle's diameter, so it never depends on brand or country. Whenever a pattern and your needles disagree, trust the mm.
A note on "old and new" UK sizes: the UK switched from Imperial numbers (14, 13, 12…) to metric (2 mm, 2.25 mm…) decades ago. Older British patterns and inherited needles use the Imperial numbers in the right-hand column above; modern UK patterns use millimetres, the same as everywhere else.
Which needle size should I use?
Your pattern will tell you, but if you're choosing yourself, match the needle to your yarn weight. As a rough guide:
| Yarn weight | Typical needle (metric) |
|---|---|
| Lace | 1.5–2.25 mm |
| Super fine / sock | 2.25–3.25 mm |
| Fine / sport | 3.25–3.75 mm |
| Light / DK | 3.75–4.5 mm |
| Medium / worsted | 4.5–5.5 mm |
| Bulky / chunky | 5.5–8 mm |
| Super bulky | 8–12.75 mm |
| Jumbo | 12.75 mm + |
Guidelines are from the Craft Yarn Council; see the full [yarn weights chart →](/tools/yarn-weights).These are starting points, the needle size that gives you the pattern's gauge always wins over the size on the label. ([How to knit a gauge swatch →](/learn-to-knit/gauge-and-tension))
What about Japanese needle sizes?
Japanese patterns use their own numbering (a "号"/gō system) and metric. If you're working from a Japanese pattern, convert via the millimetre size, which is the common reference across all systems.
Frequently asked questions
Why are US and UK needle sizes numbered differently?
They developed separately and were never standardised together. They also run in opposite directions, US numbers increase with size, old UK numbers decrease. The metric (mm) measurement avoids the confusion entirely.
What does "old and new" UK needle sizes mean?
"Old" refers to the traditional British Imperial numbers (14, 13, 12…); "new" refers to the metric millimetre sizes the UK adopted later. Old patterns use Imperial; modern ones use mm.
Which needle size is best for a beginner?
A mid-range 4.5–5.5 mm (US 7–9) with a smooth worsted-weight yarn is the easiest to handle while learning — big enough to see your stitches, not so big it's awkward. (What you need to start knitting →)
Co-founder and editor of Knyt. Avid knitter!
