This crochet hook size chart will help you compare and convert hook size measurements. The United States uses letters, numbers, and the metric (mm) system to measure crochet hooks. The United Kingdom uses numbers, and many other countries use the metric system. This conversion chart will help you compare and accurately measure what hook size you need for your next project.  

Also, keep in mind that the letter and number system may vary from the manufacturer, so it is always best to rely on metric (mm) sizing to get the most accurate measurement.

Crochet hooks come in a wide range of sizes. The size of a hook is measured by the diameter of its shaft; the shaft is located in the small space before the thumb rest on a crochet hook. For standard hooks, the smaller the number, the smaller the hook; the higher the number, the larger the hook.

Tip: The size of a crochet hook correlates with the size or weight of the yarn. Crochet patterns will recommend a hook size to help you make the pattern as close to the original design as possible. 

Crochet Hook Size Chart

This crochet hook size chart will help you compare and convert measurements. In this chart, you will notice that the United States uses letters and numbers for their hook sizes, and the United Kingdom and Canada use a numbering system. Countries like Australia and New Zealand use metric sizes. It is helpful to understand these differences when reading crochet patterns.

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Metric

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2 mm

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2.25 mm

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2.5 mm

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2.75 mm

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3 mm

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3.25 mm

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3.5 mm

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3.75 mm

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4 mm

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4.25 mm

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4.5 mm

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4.75 mm

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5 mm

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5.5 mm

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6 mm

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6.5 mm

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7 mm

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7.5 mm

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8 mm

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9 mm

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10 mm

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12 mm

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15 mm

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16 mm

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19 mm

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25 mm

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 35 mm

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US

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h1

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B-1

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2

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C-2

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2

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D-3

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E-4

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F-5

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G-6

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h

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7

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h

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H-8

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I-9

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J-10

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K-10 1/2

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h

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g

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L-11

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M/N-13

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N/P-15

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O

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P/Q

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Q

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S

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T/U/X

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Y

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UK

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14

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13

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122

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12

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11

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10

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2

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9

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8

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h

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7

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h

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6

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5

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4

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3

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h

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g

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0

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00

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000

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f

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f

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h

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g

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f

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h

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Note: Steel crochet hooks have a different numbering system than regular crochet hooks. Steel hooks are used to crochet more intricate projects that use thread or lace. You can go here if you'd like to learn more about steel crochet hooks.

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I hope this article was helpful! If you have any additional questions, feel free to join my Crochet Guru Facebook Group. This group is for you to share pictures, ask questions, and help each other out!

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This chart can help you convert one measurement system to another. For example, if you have an 8 mm crochet hook, use the chart above to determine its letter. In this case, the 8 mm hook would convert to an L-11 hook.

What Hook Size Should I Use?

There are many ways to figure out what crochet hook size to use. Here are the best ways to figure it out:

• Yarn Label
• Crochet Pattern
• Crochet Swatch

Yarn label - all yarn has a specific thickness and weight. Therefore, a yarn label will tell you precisely what size crochet hook to use in order to get the best outcome.

Crochet pattern - most crochet patterns should tell you the size of hook you need. 

Crochet swatch - If you still don't know what hook size to use, it is always best to make a swatch. A crochet swatch is a small, crocheted square piece of fabric made up of 15-30 stitches. You can use the swatch to compare it to the pattern gauge information. If the swatch is much larger than the gauge, you know you need to switch to a smaller hook size.

How to Check Gauge

Gauge refers to the number of stitches and rows per inch. The stitches are counted horizontally, and the rows are counted vertically.  Most patterns will tell you the pattern's gauge. 

For example, a pattern could say 20 stitches and 22 rows = 4 inches with an I/9 crochet hook. You would then take your I/9 crochet hook and crochet a swatch with 2o stitches across and 22 rows down. 

After you crochet this swatch, you will need to check your gauge to see if it matches up with their gauge. To do this, you will grab a measuring tape and measure across the center of the square to get the most accurate measurement. You will need to measure both vertically and horizontally. If you get the same results, in this case, it would be 4 inches going both ways; then, you met the gauge requirements. 

If your swatch is bigger than the pattern's, you will need to use a smaller crochet hook. If your swatch is too small, you will need to use a bigger hook. 

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