The diameter of a hook shaft determines the hook size and stitch size. Hook sizes are measured in millimeters and are available from as small as 2 mm to 20 mm or larger!
Hooks can be labeled with US sizes, which uses numbers and letters. A U.S. size G hook is 4.25 mm in diameter. In the UK and Canada, they also use numbers.
Australia and New Zealand use metric sizes. The table above is a great reference for comparison.
Generally, the larger or thicker the yarn, the larger the hook you need. Thicker yarn uses a larger crochet hook. There are many techniques to learn in crochet. Understanding crochet hook sizes are just part of the knowledge you need to acquire. Don't worry. It's simple, and the charts below will help you.
For a complete overview of all things crochet hooks, please visit my post - Crochet Hooks - My complete guide to all the different types & Styles.
Crochet is such a wonderful art, full of creative stitches, patterns and beautiful yarns. Knowing the hooks is part of learning.
Steel hooks are also known as "yarn hooks" and should only be used for fine lace yarns. They come in numbered sizes that get larger as the diameter or millimeters get smaller.
These crochet hooks range in size from 0.6 mm thick size 12 to 3.25 mm thick size 00. You can find the conversion for thread hooks above.
How do you know what size crochet hook to use?
Choosing the right size crochet hook follows a process.
In most crochet patterns, they have a suggested gauge with a certain crochet. This shows how many stitches you should have per inch.
You should make a swatch of about 4 inches in the stitch pattern you are going to use in your project. Wash your swatch, let it dry and measure your stitches. Super important for crocheted items like a sweater or top.
If your square is smaller than what the pattern calls for, go up a hook size. Or go down a size if your square is too large.
If you have purchased yarn and don't have a pattern in mind, the label has a suggestion for the size of hook to use and also what gauge you should get.
You will find a crochet hook size to fit the projects you make.
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Popular brand crochet hook sizes
Some brands don't produce hooks in the sizes, so it's helpful to know what they make so you can have the right hooks from your favorite brands.
Types of crochet hooks
Types of crochet hooks vary not only in size but in materials they are made from. I go into more detail in my Guide to Crochet Hooks. Below is an overview.
Steel: These crochet hook sizes are the smallest. Refer to the table above. Used for fine yarn crochet, such as rugs.
Aluminum: The most popular hook choice because the yarn slides smoothly. Aluminum crochet hooks are available in a wide range of sizes.
Plastic: Available in a wide range of sizes. Ideal for beginners because they are cost effective.
Bamboo: Available in many sizes but not in the smaller sizes. The largest is 25 mm.
Wood: Wood is used to make crochet hooks as well. They often have beautifully carved handles or are just a regular shape.
Tunisia: Longer than a standard crochet hook. This means more stitches can be held on the hook while working.
Ergonomic: The specially designed shape of the handle is to reduce the strain on your working hand.
The Knook: A long crochet hook with a hole through one end. You thread a piece of yarn through the hole. You can create stitches that look like knitting.
Your questions answered
What is the most common crochet hook size?
A G/H crochet hook, (a 6 in Canada and the UK, and 5.00mm in metric,) is excellent for beginners. It is also used for all types of projects.
How does the size of the Crochet hook affect?
The smaller the hook size, the smaller the yarn gaps and the tighter the connections between loops. For a larger crochet hook, the opposite is true. Keep in mind that yarn weight also affects the finished product.
What if I use a larger crochet hook?
The gauge will be larger, thus making a larger finished item.
What size is a 2.5mm crochet hook?
It is still known as a 2.5mm crochet hook in the US size, as there is no direct equivalent. In the UK/Canada size, it is 12.
What is a size G crochet hook?
In US size, a G size crochet hook is also known as a 6. In metric, it is 4.00mm, and in the United Kingdom and Canada, it is 8.
What is a size 7 crochet hook?
A US size 7 and a UK and Canadian size 7 are the same size, but it is 4.50mm in metric.
What is a size 8 crochet hook?
Also known as a size H in the United States, it is a 6 in Canada and the United Kingdom and is 5.00mm in metric size.
What size crochet blanket hook?
Generally, the best crochet hook size for a blanket is H/8 (5mm). However, it depends on the yarn weight of the yarn you are using.
What size crochet hook for 4 ply wool?
The best size crochet hook for 4 ply wool is 2.50mm - 3.00mm, US E / 4, and 12-9 for UK / Canada. What are all the crochet hook sizes?
Crochet Hook Conversion Table
3.125 mmD -
3.5 mmE/4 -
3.75 mmF/5 9
4.25 mm G -
4.50 mm US7 7
6.00 mm J/10 4
6.50 mm K/10.5 3
11.50 mm P/16 -
15.75/16 mmQ -
19 mmS -
(Based on Craftsmanship Council standards)
New tools from The Hook Nook. An assortment of Hook Nook tools and hooks on a blue background.
Crochet hook yarn hook sizes/steel hook crochet sizes
3.50 mm 00
3.25 mm 0
2.75 mm 1
2.70 mm 00
2.55 mm 0
2.35 mm 1
2.10 mm 3
2 mm 4
1.90 mm 5
1.80 mm 6
1.75 mm 4/0
1.70 mm 5
1.65 mm 7
1.60 mm 6
1.40 mm 9/8
1.30 mm 10
1.25 mm 9/4
1.15 mm 10
1.10 mm 11
1.05 mm 11
1 mm 12/6
0.95 mm 13
0.90 mm 14/8
0.85 mm 13
0.75 mm 14/10
0.60 mm 12
(Based on Craft Yarn Council standards).
Yarn store good yarn
As you can see from the chart, hook size varies from place to place. It is important to know the conversions. Useful when you want to knit a pattern written in another country.