Crochet Hook Sizes & Conversion Chart

Crochet Hook Sizes & Chart – A Complete Guide

Learn all about crochet hooks with this complete guide to crochet hook sizes including a crochet hook size conversion chart so you always know which crochet hook to use.

Before we begin, I would like to thank you for visiting Jo to the World Creations, a site dedicated to helping you give the gift of crochet.

More free patterns (that make awesome crochet gifts) are on the way! Sign up for my emails, follow me and never wonder “What should I make for…” again!


Delivered to your inbox


Unsubscribe at any time. 

Delivered Socially

Follow Me on 

Pinterest Hidden Image

What is a Crochet Hook?

A crochet hook (also called a crochet needle) is a special tool that has a u-shaped curve at the end. Hooks can be made of aluminum, bamboo, wood, plastic, steel or other materials.

Crochet hooks are what allow you to crochet by pulling yarn (or other materials) through loops to make stitches.

Crochet hook in action

Crochet hooks are held in your dominant hand. Crochet hooks are the same whether you are right or left-handed (there are no hooks specifically for right-handed or left-handed crocheters). Learn the easiest ways to hold a crochet hook.

Parts of a Crochet Hook

Understanding the different parts of a crochet hook will help you learn how the size of crochet hooks are determined.

Crochet hook parts

A crochet hook is made up of 5 parts:

  1. The Head – the tip of the hook that you will insert into stitches.
  2. The Throat – what catches the yarn and guides it onto the working area/shaft.
  3. The Working Area / Shaft – holds the loops you are working on. The shaft is also where the crochet hook is measured and determines the size of your stitches.
  4. Flattened Area – the place you can put your finger or thumb depending on how you grip your hook.
  5. The Handle – is the bottom part of the hook and controls the overall movement of the hook.

Affiliate Disclosure: This post may contain affiliate links meaning I may receive a commission for purchases made through links in this post at no extra cost to you. As an Amazon Associate, I earn from qualifying purchases.

How to Measure a Crochet Hook

The size of a crochet hook is determined by the Shaft of the hook. Crochet hooks are measured across by the Shaft in millimeters (mm) and the amount of millimeters across determines the size. Measuring across means measuring the diameter (not going around the shaft).

Measure a Crochet Hook with Measuring Tape

Measuring Crochet Hooks

To measure a crochet hook, take a measuring tape that uses millimeters and put the end (the zero) on the very left side of the shaft. Count the number of millimeters across until the right side of the shaft. The total number of millimeters is the size of your crochet hook. In the example below, the shaft measures 5.00 mm across and is a 5.00 mm crochet hook.

Measure Using a Swatch Ruler and Needle Gauge

Measure crochet hook with needle gauge

Another way to measure a crochet hook is to use this Clover Swatch Ruler and Needle Gauge. It is one of my favorite tools and I use it every time I check my gauge but it’s also great for measuring crochet hook sizes. The middle piece comes out and you can easily insert your hook into the opening to see what size your hook is.

Crochet Hook Sizes

Many hooks are labeled with a letter and/or a number and have a measurement such as: H/8 – 5.00 mm.

Crochet hook size

Let’s take a look at what this means. In this example, H/8 is the US Sizing reference and the measurement, 5.00 mm, is the measurement of the diameter of the shaft in metric units, which is the UK Sizing.

The Craft Yarn Council has been advocating for crochet hook manufacturers to put both the US and UK sizes on every crochet hook label but that’s not always the case. As a beginner crocheter, you’ll want to know the difference between the two sizes so you can easily find the measurement of your hook when needed.

At a high level, there are three things to know about crochet hook sizes:

  • UK / Metric Crochet Hook Sizes are measurements, in millimeters such as 5.00 mm, which is measured across the shaft of the hook.
  • US Crochet Hook Sizes include a letter and/or number such as H/8. The lettering system goes from B, which is the smallest hook to T, which is the largest hook.
  • Steel Hooks (also called Thread Hooks or Lace Hooks), which are used for lace-weight yarn are different from regular hooks. They can still be measured in millimeters but the US sizing system is reversed so the higher the number, the smaller the hook. The US sizing system referenced below does not apply to steel hooks (see further down on this post for more info on steel hooks).

Crochet Hook Sizes UK / Metric

Crochet hooks range in size from 0.35 mm to 30 mm, measured across the crochet hook. Crochet measurements are often called metric units or UK sizing because they use millimeters (mm).

All crochet hooks can be measured in mm. In fact the Craft Yarn Council recommends that you base the size of a crochet hook off the measurement and not the US letter and/or number.

There used to be an “Old UK Crochet Hook Size” format where each hook size had a number ranging from 14 for the smallest to 000 as the largest but this is rarely used anymore. If you see a chart with a heading called “UK” and there are numbers from 14 – 000, you can ignore these and just reference the measurement in millimeters as that is what is used today.

Crochet Hook Sizes US

Crochet hooks produced in the United States of America use a letter to state the size.

The letter system:

  • Starts at B, which is the smallest hook size in US sizing (2.25 mm)
  • Ends with T, which is the largest hook in US sizing (30 mm).

Many times the letter is accompanied but a number (such as B/1 or H/8) but sometimes there is not. For example, an “S” hook in US terms, which is a 19 mm hook, does not have a number. Also, there are some hook sizes that don’t have a letter or number in US sizing but still exist such as a hook that is 12 mm hook.

One flaw with the US Lettering System is that what is an H/8 hook to one company that manufactures hooks could be slightly different from another company producing an H/8. For that reason, always follow the measurement (i.e. 5.00 mm) on the crochet hook label instead of the US letter.

What are the Crochet Hook Sizes?

Regular crochet hooks range from 2.25 mm (or a size B/1 in US sizing) all the way to up to 30 mm (or T/X in US Sizing).

The most commonly used hooks, especially for beginners are aluminum hooks in sizes D – 3.125 mm through K – 6.50 mm. These 8 sizes are so popular that many companies offer a crochet hook set that includes these sizes.

Crochet hook set

I personally use Simplicity Aluminum Crochet Hooks and they offer this Crochet Hook Set for the most commonly used sizes (3.125 mm – 6.50 mm or D / K). I purchased a similar set when I first started crocheting and have never had to replace them! As I gained more experience, I added to my crochet hook collection with smaller and larger hooks but to this day, I use these hook sizes for the majority of my crochet projects.

What is the Best Crochet Hook Size for Beginners?

As a beginner, using a hook between the sizes of H/8 (5.00 mm) and 1/9 (5.50 mm) are great to start with because they are not too big and not too small. They both work well with either size 3 (light/dk) or size 4 (medium/worsted weight) yarn, which are the easiest to practice with.

Crochet Hook Size Chart

Oftentimes, a hook will only have a letter and/or a number (the US hook sizing) and not the measurement (the UK hook sizing). Or your hook may only have the measurement but the pattern recommends a hook size by just stating the US hook sizing. 

When you only have one part of the hook size, you may need to refer to this handy Crochet Hook Sizes Conversion Chart. Here you can find the corresponding measurement (metric / UK sizing) to the US hook sizing and vice versa.

Crochet Hook Size Conversion Chart

Metric / UK SizingUS Sizing
2.25 mmB/1
2.50 mm
2.75 mmC/1
3.125 mmD
3.25 mmD/3
3.50 mmE/4
3.75 mmF/5
4.00 mmG/6
4.25 mmG
4.50 mm7
5.00 mmH/8
5.25 mmI
5.50 mmI/9
5.75 mmJ
6.00 mmJ/10
6.50 mmK 10 1/2
7.00 mm
8.00 mmL/11
9.00 mmM/N /13
10.00 mmN/P /15
11.50 mmP/16
12.00 mm
15.00 mmP/Q
15.75 mmQ
16.00 mmQ
19.00 mmS
25.00 mmT/U/X
30.00 mmT/X
Crochet Hook Sizes Conversion Chart from Metric (mm) / UK to US Sizing

Join my email list (it’s free!) and get a printable Crochet Cheat Sheet, which includes a Crochet Hook Size Conversion Chart of the most commonly used hook sizes.

Most Common Crochet Hooks

The chart above references all the regular hook sizes. However, there are only approx. 14 commonly used hook sizes. Some of these have slight variations. For example, there’s an I hook (without a number) that is 5.25 mm and there’s an I/9 hook that is 5.50 mm.

Here are the most common crochet hooks in order from smallest to largest: B/1 (2.25 mm), C/2 (2.75 mm), D/3 (3.25 mm), E/4 (3.50 mm), F/5 (3.75 mm), G/6 (4.00 mm), H/8 (5.00 mm), I/9 (5.50 mm), J/10 (6.00 mm), K/10.5 (6.50 mm), L/11 (8.00 mm), M/N-13 (9.00 mm), N/P-15 (10.00 mm), P/16 (11.50 mm).

Printable Crochet Hook Size Chart

Here is a free crochet hook size chart you can print, save to your files or save to Pinterest. If you are on a computer, right click and choose “save as” and then you can print the image. If you are on a mobile device, hold down on the image and then click “save to photos.”

Crochet Hook Sizes Chart

Impact of Crochet Hook Size

Let’s take a look at the difference between using a small crochet hook, medium and large crochet hook and the impact it has on your work.

For this demonstration, I made three swatches using the exact the same yarn (Impeccable by Loops & Threads, which is a size 4 (medium/worsted weight)) and made the exact same number of stitches and rows (10 single crochet stitches in each row and 10 rows in total).

Crochet hook size

As you can see in the above image, using a B/1 (2.25 mm) hook, made the swatch very small and the stitches very tight. The piece is dense and very stiff. On the other hand, using an N/P/15 (10 mm) hook, made the swatch very large and the stitches very loose. The piece flows nicely.

Which crochet hook you use can drastically impact the size, how close the stitches are and how the piece flows.

How Do I Know Which Crochet Hook Size To Use?

You can determine which hook size to use by 1) following the pattern recommendation (at least to start with as you check your gauge), 2) reading the yarn label, or 3) you can use the most common crochet hook size for each type of yarn weight.

1. Hook Size on a Pattern

All crochet patterns will indicate what size hook is recommended to use when making that item. 

For example, on my Classic Baby Blanket crochet pattern, I recommend an H/8 (5.00 mm) hook. However on my Easy Bookmark crochet pattern, I recommend an F/5 (3.75 mm) hook.

2. Hook Size on a Yarn Label

All yarn labels also indicate what size hook is recommended to use when using that yarn. 

Crochet hook size on yarn label

The yarn pictured above, Impeccable by Loops & Threads, recommends using a 5.00 mm – US H/8 Crochet Hook.

3. Hook Sizes for Yarn Weights

Yarn weights range from size 0 (lace) to size 7 (super bulky). You can read more in my guide to yarn weights.

Crochet Hook Sizes Yarn Weights Chart

Here are the recommended hook sizes for each yarn weight:

  • Size 0 – Lace (fingering or 10-count crochet thread) – B/1 (2.25 mm) or Steel Hooks
  • Size 1 – Super Fine (sock, fingering, baby) – B/1 (2.25 mm) to E/4 (3.5 mm)
  • Size 2 – Fine (sport, baby) – E/4 (3.5 mm) to 7 (4.5 mm)
  • Size 3 – Light (dk, light worsted) – 7 (4.5 mm) to 1/9 (5.5 mm)
  • Size 4 – Medium (worsted, afghan, aran) – 1/9 (5.5 mm) to K/10.5 (6.5 mm)
  • Size 5 – Bulky (chunky, craft, rug) – K/10.5 (6.5 mm) – M/13 (9 mm)
  • Size 6 – Super Bulky (roving) – M/13 (9 mm) to Q (15 mm)
  • Size 7 – Jumbo – Q (15 mm) or larger

Crochet Hook Size + Yarn Weight = Outcome

Don’t be surprised though if a pattern recommends a hook size that is different than what is recommended on the yarn label.

For example, in my Simple Baby Blanket crochet pattern, I used a K/10.5 (6.50 mm) hook and size 3 (light/dk) yarn, even though the yarn label for that yarn recommends using a G/6 (4.00 mm) hook and the recommended hooks sizes are G/6 (4.00 mm) – I/9 (5.50 mm). Mixing and matching hook sizes with different size yarns allow you to achieve unique designs. 

Your crochet hook size along with the weight of your yarn (how thin or thick it is) will determine the size of your finished item, how close the stitches are whether the piece flows or is stiff. 

  • If you use a very small hook with thick yarn, it will create a very dense, stiff fabric. 
  • If you use a large hook with thin yarn, it will create a loose fabric that flows.

While there are recommended hook sizes for each yarn type, it’s absolutely okay to break “the rules” (and they aren’t actually rules, just recommendations). Pablo Picasso even said “Learn the rules like a pro so you can break them like an artist.” This is especially true in crochet. Get creative and experiment with different hook sizes and yarn weights. That’s when the magic happens.

Crochet hooks

Hook Sizes & Gauge

The gauge of your work is the number of stitches and rows in a designated area. For example, if the gauge stated on a pattern is 4″ x 4″ = 13 single crochet stitches and 11 rows, what this means is that within 4″ measured horizontally, you should have 13 single crochet stitches and within 4″ measured vertically, you should have 11 rows.

Crochet hook sizes along with your tension and yarn weight will determine the gauge.

If we look at the three swatches I made with three different hook sizes and measured the number of stitches within 1″ measured horizontally and the number of rows within 1″ measured vertically, you will see that the number of stitches and rows within a 1″ x 1″ area are drastically different.

Crochet hook size and gauge

The swatch made with a B/1 (2.25 mm) hook had 4 sc (single crochet stitches) and 5 rows within a 1″ x 1″ area whereas the swatch made with an N/P – 15 (10.00 mm) hook had only 2 sc and 3 rows within a 1″ x 1″ area.

Note that most patterns have a gauge of 4″ x 4″ (not 1″ x 1″ as referenced above) to get a more accurate measurement – this was just for demonstration purposes.

It is very important to check your gauge for every project. Learn how to check gauge in my Complete Guide to Crochet Gauge.

Types of Crochet Hooks

Crochet hooks are made out of aluminum, plastic, bamboo, wood, steel and other materials. In general:

  • Most hooks that are 2.0 mm and under are made of steel.
  • The most common crochet hooks range from 2.25 mm – 6.5 mm and are made of aluminum.
  • Most hooks over 6.0 mm are made of bamboo, wood or plastic.

Here are the main types of crochet hooks:

  • Aluminum hooks (recommended for beginners) – these are the most popular and most often range in size from B/1 (2.25) to K/10.5 (6.5 mm).
  • Ergonomic hooks – these are regular hooks but have grip handles to help with hand pain and cramping.
  • Plastic Crochet Hooks – these are regular hooks but made of plastic.
  • Wood/Bamboo Crochet Hooks – these are regular hooks but made of wood/bamboo.
  • Tunisian hooks – Tunisian crochet is a type of crochet that holds several loops on a hook at once (similar to knitting) and it requires special hooks. Learn how to Tunisian crochet.
  • Steel Hooks – these hooks are used for very thin yarn and threads. The US sizing for these hooks is the reverse of what is it for regular hooks. For steel hooks, the larger the number, the smaller the hook (more info below).
Crochet hook case

Crochet Hook Case

Once you get your crochet hooks, you’ll also want to get a crochet case for them such as this Crochet Hook Organizer.

Steel Hook Sizes

Most hooks that are 2.0 mm and under are made of steel and are sometimes called “steel hooks,” “thread hooks,” or “lace hooks.” These hooks are different from regular hooks. These hooks should not be confused with aluminum hooks.

Steel hooks are used for very thin yarn and threads and generally are used by more experienced crocheters. The US sizing system for steel hooks is different from regular hooks. For regular hooks, the letters/numbers start with B/1 for a 2.25 mm hook, which is the smallest and go to T/X for a 30 mm hook, which is the largest. With steel hooks, it’s the reverse and there are only numbers to indicate the US sizing and not letters. The US Sizing for a steel hook that is 3.50 mm (the largest) is 00. And the US Sizing for a steel hook that is 0.75 mm (one of the smallest) is 12.

Crochet Hook Sizes Tips

  • The amount of yarn that is required for a pattern is based on the hook size that the designer used. If you need to change the hook size to obtain the gauge, you may require more or use less yarn.
  • Write down the crochet hook you use to start a project. You’ll want to continue using it for the entire project and it can be easy to forget which hook you started with.
  • Crochet hooks are relatively inexpensive so it’s good to try different ones out as you learn how to crochet.

Frequently Asked Questions About Hook Sizes

What are the Sizes of Crochet Hooks from Smallest to Largest?

Regular crochet hooks range from B/1 (2.25 mm), which is the smallest to T/X (30 mm), which is the largest.

What Size is a G Crochet Hook in MM?

There are two G hooks (the G means that it is in US sizing): 1) The G/6 hook is 4.00 mm in metric / UK sizing. 2) The G hook is 4.25 mm in metric / UK sizing. For this second G hook, there is no number associated with it.

What Size/Letter is 4.5 mm Crochet Hook in US?

A 4.5 mm crochet hook is a size 7 in US crochet hook sizing. There is no letter assigned to a 4.5 mm crochet hook, it is simply referred to as size 7 in US sizing and 4.50 mm in metric/UK sizing.

What Size/Letter is a 5mm Crochet Hook in US?

A 5mm (or 5.00 mm) crochet hook is H/8 in US crochet hook sizing. It is one of the most commonly used crochet hooks and a great crochet hook for beginners.

What Number is a Size H Crochet Hook in mm?

An H/8 crochet hook (the H/8 means that it is in US sizing) is a 5.00 mm hook in metric / UK sizing.

What Size/Letter is a 5.50 mm Crochet Hook in US?

A 5.5 mm (or 5.50 mm) crochet hook is 1/9 in US crochet hook sizing. It is one of the most commonly used crochet hooks and a great crochet hook for beginners. There is also an “I” hook, which is 5.25 mm and does not have a number associated with the “I.”

What Size is a J Crochet Hook?

There are two “J” sized crochet hooks (the “J” means that is in US sizing): 1) A 5.75 mm hook (in metric / UK sizing) is a J hook in US sizing. There is no number that goes with the “J.” 2) A 6.00 mm hook (in metric / UK sizing) is a J/10 in US sizing.

I hope this guide to crochet hooks has helped you understand the different sizes and types so that you can find the right crochet hook to use on your project.

More Posts You Might Like:

Download. Print. Keep.

Get Instant Access to ALL Printable Patterns

Make your crocheting more enjoyable, relaxing and productive with printable PDF patterns. 

  • 100+ premium crochet patterns.
  • Download, save and print from any device.
  • No ads or popups!

Not sure yet? Take a look at the Pattern Library and see all the patterns you can download once you’re a member. 

Membership Promo

Save with Pattern Bundles

For a limited time, I’ve grouped some of my most popular crochet patterns and I’m offering them as pattern bundles where you can get the printable versions for one low, discounted price. Check out these incredible Crochet Pattern Bundles.

Easy Baby Blanket Pattern Bundle

Easy Baby Blanket Bundle

With this Easy Baby Blanket Bundle, you’ll get SIX easy crochet baby blankets as printable downloads. Each pattern includes step-by-step instructions and a full video tutorial. 

Delightful Baby Blanket Crochet Patterns Bundle

Delightful Baby Blanket Bundle

This incredible deal includes six SIX blanket patterns that are a delight to make and create truly stunning blankets – all as printable PDFs for one low, discounted price.  

Moss Stitch Bundle

Moss Stitch Pattern Bundle

All your favorite Moss Stitch patterns in one bundle! Get SEVEN easy Moss Stitch crochet patterns as ad-free, print-ready PDFs to print, save and keep forever.

Crochet Cheat Sheet

Free Crochet Cheat Sheet

Get instant access to this Ultimate Crochet Cheat Sheet! Plus you’ll receive free patterns for crochet gifts delivered right to your inbox!

Featured Crochet Patterns

Beautiful Crochet Baby Blanket Pattern

Beautiful Crochet Baby Blanket Pattern – Free

Easy placemat crochet pattern free

Easy Free Crochet Placemat Pattern – Modern Placemats

Crochet tote bag

Easy Crochet Tote Bag Pattern – Free

Adorable Baby Blanket Crochet Pattern

Adorable Baby Blanket – Free Crochet Pattern

Simple Crochet Scarf Pattern

Simple Crochet Scarf (with Tassels) Pattern

Infinity scarf crochet pattern

Easy Infinity Scarf Crochet Pattern – Free

Continuous Granny Square Blanket

Continuous Granny Square Blanket Crochet Pattern

Classic Baby Blanket Crochet Pattern

Classic Baby Blanket Crochet Pattern

Crochet summer headband

Crochet Summer Headband Pattern Free

Lacy Baby Blanket Crochet Pattern

Lacy Baby Blanket Crochet Pattern

Bohemian Crochet Pillow Pattern

Bohemian Crochet Pillow Pattern

Simple Baby Blanket Crochet Pattern

Simple Baby Blanket – Free Crochet Pattern

Pattern Collections

Free Crochet Baby Blanket Patterns

75+ Fast, Easy & Free Crochet Baby Blanket Patterns

Baby Girl Crochet Blanket Patterns

30+ Beautiful Baby Girl Crochet Blanket Patterns

Baby Boy Crochet Blanket Patterns

30+ Cute, Easy & Free Baby Boy Crochet Blanket Patterns

Free Crochet Scarf Patterns

75+ Beautiful & Easy Crochet Scarf Patterns – Free

Crochet stitches for blankets

Best Easy Crochet Stitches for Baby Blankets

Unusual Crochet Patterns Free

40+ Unusual Crochet Patterns – Free!

Summer crochet projects

60+ Summer Crochet Projects

Small crochet projects

80+ Small Crochet Projects

Free Patterns for Crochet Gifts

Never miss a pattern! Get all my secrets to making incredible crochet gifts as well as new free crochet patterns and exclusive deals when you sign up for my newsletter (it’s free!).

Free Email Series

Secrets to Making
Crochet Gifts

Subscribe to my emails and get patterns & tips to help you make the best crochet gifts for everyone in your life.