Does Crochet Hook Size Matter?

When first learning to crochet, one of the questions I asked my instructor was “Does it matter what size crochet hook I use?”  Based on the look on her face, the answer was clear:

The size of the crochet hook does really matter to the outcome of your project.  Both in crochet and in knitting, changing the size of the hook or needle will dramatically change the shape and design of the project.  Carefully following the instructions outlined in your pattern and choosing the best crochet hook size is important. Understanding why crochet hook size matters will help you create the best possible projects.

Why Does Crochet Hook Size Matter?


Hook size matters in crochet for several different reasons.  First and foremost, hook size determines the size of the stitch.  Different hook sizes produce different sized stitches. Changing hook size will change the size of your completed project.

Why Crochet Hook Size Changes the Size of the Project

This comes into play most in the final size of your finished project. Using the wrong crochet hook size will either make your project larger or smaller than the outline in the pattern.  While that might not be a big deal for a scarf or blanket, for crocheted clothing items size of the finished project is very important.

There’s nothing more frustrating than finishing your first crochet cardigan only to discover it’s far too small. Or finishing an adorable stocking hat only to have it slouch off your head because it’s too large.  Matching your hook size to the suggested hook size in the pattern will help ensure your end project is the size you intended.

What happens if you use a larger crochet hook than the pattern calls for?

Using a crochet hook that is larger than the size your pattern calls for will generally result in the finished item being larger or have looser stitches than the original.  Larger crochet hooks create larger stitches meaning each row will be slightly longer and slightly taller than the pattern recommendation.  If you select too large of a hook, you may not be able to complete the project at all.

What happens if you use a smaller crochet hook than a pattern calls for?

In contrast, using a smaller crochet hook than the size recommended in your pattern will result in projects that are smaller than the pattern called for.  There is also some evidence to support that using too small of a crochet hook may also slow down the speed of your crocheting.

A Project to Test Crochet Hook Size

One way to test this idea and visually see for yourself what happens if you change crochet hook size is to conduct a simple test.  Select an easy crochet pattern like a dish scrubber, a baby hat, or even a simple square.  Choose a mid-weight yarn (nothing too bulky, nothing too fine) and four crochet hooks in different sizes. Try to select at least one small hook, one medium-sized hook and then one over-sized crochet hook (see below for different size options).

Then, create the same pattern, with the same yarn with each of the different sized crochet hooks.  The finished products will be four of the same item, each in a different size.  It will help you best understand exactly how crochet hook size changes the size of your finished product.

The Right Size Crochet Hook Helps Create More Uniform Stitches

Besides the size of the finished product, there are other reasons to choose the right size crochet hook.

Crochet hook size also matters to getting uniform stitches throughout your project. Selecting a crochet hook that is too large or too small for the type of stitches you plan to complete can mean you struggle to hold the yarn and put together nice, even stitches.  This especially becomes important for detailed crochet pieces like amigurumi or lace.

Certain types of yarns also do better with certain size crochet hooks. Bulky yarns do best with large hook sizes.  Fine yarns and threads are better for tiny, delicate crochet hook sizes. In general, the bigger the yarn, the larger the crochet hook.  Most standard skeins of yarn sold in the United States will come with a recommended crochet hook size posted on the label.  While the label is just a guideline (see determining crochet gauge below), by reviewing it before you begin your project, you’ll stand the best chance of using the best hook size for the type of yarn you purchased.

Getting the Most Professional Outcome Possible

For all of these reasons, crochet hook size determines how professional your project will look when finished.  Choosing the wrong crochet hook size may end up with an end project that just looks ‘off.’

I strongly believe if you’ve done the work to crochet something in the first place, why not strive for the best looking project?  While homemade doesn’t have to be perfect, it’s important to take the steps to get the best possible outcome.  Following some simple steps to get the right size crochet hook, is all it takes to get a more professional looking product.

Determining the Best Crochet Hook Size

Now that you are aware of how important crochet hook size is to your finished product, it is time to learn about how crochet hook sizes are determined.  Unfortunately, there are no standard crochet hook size regulations.  Crochet hooks can vary by material, brand or where they were produced.

While there are some general principals (e.g. metric vs. US lettering) to learn about crochet hook sizing, each manufacturer determines the size of the crochet hooks they sell.  The size typically determines the diameter of the shaft of the crochet hook.

The next time you visit a craft store, hold up a crochet needle in the same size from two different manufacturers and check for yourself.  No two crochet hooks are the same!

To make matters worse, frequently the type of material a crochet hook is made out of can influence the sizing convention used. Aluminum and steel hooks (although both metal) may not use the same sizing conventions.  Plastic and wooden hooks typically go back to the country where the hooks were manufactured.

When you purchase crochet hooks, there are several different measurement systems to monitor.  I prefer to purchase crochet hooks that have the measurement conventions clearly listed on the hook itself.  That way if it’s separated from the packaging, I’m still able to determine if the hook I have is the right size for my project.  The more measurements listed the better.

Metric Crochet Hooks

Metric crochet hooks are sized by millimeters.  Given they are based on an actual measurement, oftentimes metric hooks can be sized a bit more consistently than those sized only by number or letter.  Metric crochet hooks vary in size from the very small, 0.6 mm up to the largest size 15 mm or larger.

United States/American Crochet Hooks

In contrast, the American method of sizing crochet hooks deals in either letters or numbers.  Lettered crochet hooks typically range in size from A-Q or by numbers 00-15.  The larger the letter or number the larger the crochet hook size.

Just like converting centimeters to inches, converting metric crochet hook sizes to the American system of sizing is not straightforward.  For example, an American sized G hook is 4.0 mm and an H hook is 5.0 mm.  That’s a difference of 1.0 mm in size between the two hooks. This, however, is not the same difference in size as between an H hook and an I hook.  I hooks are 5.5 mm which is only 0.5 mm between the two sizes.  The increments between the American crochet hook sizes and the metric sizes are different, which makes converting the sizes very difficult.

Other Crochet Hook Sizes

As if the two sizes were not complicated enough, the United Kingdom and Canada follow a numerical crochet hook measurement system like the United States system, but it’s backward.  The smallest crochet hooks in the UK system are typically sized 14 or 13 whereas larger crochet hooks are sized 0, 00, or 000.  It’s the exact opposite of the American system where the larger the number the larger the hook.

Sorting It All Out

If all of these different conventions cause your head to spin, don’t stress.  Most hobby and casual crocheters don’t worry much about memorizing the sizes or conversions.  It’s best to have an idea about what the different conventions of crochet hooks are, but not necessary to get caught up in knowing the specifics.

Most crochet hooks sold from recognized manufacturers will have multiple conventions listed on them.  The crochet hook will be labeled with something like:  US J / 6.0 mm / UK 4 so the conversion is already done for you right on the needle. Popular crochet patterns and most crochet books will also do the same in the pattern instructions so you don’t need to scramble to find the right hook.

If you do find yourself needing to make a conversion, a simple Google search will typically lead you to the correct hook for your project (e.g. “What size is a 3.5 mm crochet hook in US sizing?”)

Never Switch Hooks Once You’ve Started

On a final note about the differences in crochet hook sizes, because there is so much variability between materials, manufacturers, and measurements, once you choose a crochet hook for a project you must use that same crochet hook for the entire project.  Unless the pattern directs you to do so, switching crochet hooks (even if you use one marked the same size) will likely also change the stitch size and the row size.  Depending on where it occurs in the project, it could cause big issues in the final outcome.

Related Questions

How do I know what size crochet hook I have?

Occasionally a crochet hook manufacturer will only print the sizing information on the package and not on the crochet hook itself.  Or you may have decided to craft a homemade crochet hook and need to know the size of the final product.  In these situations, there are a few different options to determine what size crochet hook you have.

One option is to measure it yourself.  Starting with a flat ruler or tape measure, place the hook at the widest point (called the “shaft) on the ruler area starting at “0”. Measure the diameter (length across) of the crochet hook in millimeters.  Then use a conversion chart to determine the equivalent US sizing.

Another option is to purchase a gauge tool online or at a craft store.  Gauge tools are typically small enough to fit in your sewing kit and made out of plastic or wood.  The tool typically has 10-24 holes in different sizes cut into it.  Each hole is numbered or lettered with the crochet hook sizing convention.  To measure the hook you have, simply slide it into one of the holes on the gauge tool until it tightly fits. The size hole matches the size of your crochet hook.

Can you change the hook size of a pattern in crochet?

With all the fuss about the size of the crochet hook changing the size of the finished pattern, it is important to note that in some cases it may be okay to change the hook size of a pattern.  There are several reasons you might decide to change the hook size including sizing, owning a hook, or using a different yarn.

If you’d like to re-size a wearable item to make it fit a particular person, you may need to change the size of the hook. As long as you use the same yarn and the same number of stitches, slightly increasing or decreasing the size of the hook one or two sizes will only slightly change the size of the finished garment. This is great for things like mittens or slippers where ‘snugness’ can be an issue.  It’s not recommended for more complex wearables like sweaters.

You may also want to change hook sizes because you do not have a particular crochet hook needed in a pattern but you have a hook that is sized one larger or smaller.  In many cases, it’s just fine to switch hooks.  Just know that it will adjust the total amount of yarn used from the pattern (see tips on yarn below) and will change the finished size of the project.

Finally, you may decide that you wish to use a different yarn than the type listed in the pattern. Smaller or larger sized yarns may require a different crochet hook (see tips on yarn below) even though you use a similar number of stitches in the pattern.  To determine the new size crochet hook you should use, check the yarn packaging for suggestions.

In all cases where you plan to change the hook size, you should always create a gauge swatch first to ensure you’ve selected the right size hook for your pattern. Also, be careful about changing hook sizes with pre-packaged crochet kits like amigurumi; changing hook size may create a different sized critter, but too large of a hook change and you may also run the risk of running out of yarn.

Do different sized crochet hooks use different amounts of yarn?

The short answer to this question is, yes.  Different sized crochet hooks create different sizes of stitches because they each make a different size loop around the hook.  To determine how much yarn a particular crochet hook will use in a project, you should create a gauge swatch. You can also mark a particular length of yarn (e.g. 12 inches) and count how many stitches you are able to create with that particular length using different size needles.

While the degree to which a hook will use more or less yarn is dependent on each individual person’s crochet skill, larger hooks tend to create larger stitches and therefore tend to use more yarn.  Smaller hooks tend to create smaller stitches and therefore use less yarn.

Does yarn size matter when choosing a crochet hook?

Just like the size of a crochet hook will determine the size of a finished product, so will the size and type of yarn used in a project.  Carefully reading the label on your yarn and understanding the type of yarn you’re using will ensure that you achieve the closest outcome to the pattern you intended.

In general, yarn size is determined by how ‘bulky’ the yarn is.  Yarns that are thicker require larger crochet hooks to get nice even stitches.  Super-bulky yarns may even require jumbo crochet hooks (US Size P or larger) or finger crochet. In contrast, ultra-fine yarns or threads require very small hooks.  Read the packaging to determine which hook is the best for your yarn.  If none are listed, try a search online for suggestions or make a gauge swatch with a few different hook sizes to determine which looks the most uniform.

Notice: ob_end_flush(): failed to send buffer of zlib output compression (0) in /home/crochett/public_html/wp-includes/functions.php on line 5373

Notice: ob_end_flush(): failed to send buffer of zlib output compression (0) in /home/crochett/public_html/wp-content/plugins/really-simple-ssl/class-mixed-content-fixer.php on line 107