Size Conversion Charts for Knitting Needles & Crochet Hooks

When it comes to knitting needles and crochet hooks, the sizes are referred in different ways thanks to the differences in the US and the UK measurement systems. When you are using a pattern that mentions a specific needle or hook size, you need a handy conversion chart for knitting needles and crochet hooks.

So, here we have created a quick size conversion chart for knitting needles and crochet hooks in the UK and the US.

Knitting Needle Size Conversion Chart

The knitting needle size conversion chart will help you select the right pair of needles for your pattern.

MetricUS SizeUK Size
2.0 mm014
2.25 mm113
2.5 mm1.5
2.75 mm212
3.0 mm2.511
3.25 mm310
3.5 mm4
3.75 mm59
4.0 mm68
4.5 mm77
5.0 mm86
5.5 mm95
6.0 mm104
6.5 mm10.53
7.0 mm2
7.5 mm1
8.0 mm110
9.0 mm1300
10.0 mm15000
12.0 mm17
16.0 mm19
19.0 mm35
25.0 mm50

Crochet Hook Size Conversion Chart

For crochet hooks, the US sizes are written as a combination of alphabet and numbers. The usual US size format is a letter followed by a number. On the other hand, the UK sizes are written in simple metric numbers in millimeters (mm).  

Check out the crochet hook size conversion chart which will help you choose the correct size of crochet hook needed for your pattern.

MetricUS Size
2.25 mmB / 1
2.5 mm
2.75 mmC / 2
3.25 mmD / 3
3.5 mmE / 4
3.75 mmF / 5
4.0 mmG / 6
4.25 mmG
4.5 mm7
5.0 mmH / 8
5.25 mmI
5.5 mmI / 9
5.75 mmJ
6.0 mmJ / 10
6.5 mmK / 10.5
7.0 mm
8.0 mmL / 11
9.0 mmM / 13
10.0 mmN / 15
15.0 mmP / Q
16.0 mmQ
19.0 mmS
30.0 mmT

Even within the US, manufacturers use both numbers and/or letters as well as the metric sizing (mm) for knitting needles and crochet hooks. As the letter and number sizing varies from brand to brand, it is better to rely on the millimeter (mm) sizing, which is more accurate. 

Regardless of the size conversion guide, always create a gauge swatch and compare it to the pattern gauge information. If the swatch you made is larger than the pattern gauge, you need to switch the needle or hook and use a smaller one. Conversely, if your gauge swatch is too small, you must redo it using a larger hook or needle.

For an easy reference, here are the size conversion charts as graphics!

Here are the downloadable PDFs of size conversion charts for knitting needles and crochet hooks!

You can also check other crochet and knit resources from our website.

One Comment

  • Molly Matthews

    HELP!!! 08/24/2021

    I have a 1.75 mm (5) steel hook. What size cotton thread should I use to crochet baby blanket edging?

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