Crochet Hook Sizes Guide (US vs. UK + Yarn Weight Chart)
Introduction
Choosing the right crochet hook size is one of the most important steps in starting any project. But with different sizing systems—US letters, millimeters, and UK numbers—it can be confusing for beginners.
This guide breaks down every crochet hook size, the difference between US and UK systems, and how to match hooks with yarn weights using an easy-to-follow chart.
1. Crochet Hook Size Systems Explained
Crochet hooks are labeled in three main ways:
a. Millimeters (mm)
The most universal and accurate measurement.
Example: 5.0 mm
b. US Hook Sizes (Letter System)
Common in American crochet patterns.
Example: H/8, I/9
c. UK Hook Sizes (Number System)
Uses numbers instead of letters.
Example: Size 7, Size 4
Each system refers to the diameter of the hook head.
2. Complete Crochet Hook Size Conversion Chart
Below is a simplified chart for beginners:
| Metric (mm) | US Size | UK Size |
|---|---|---|
| 2.00 mm | — | 14 |
| 2.50 mm | — | 12 |
| 3.00 mm | — | 11 |
| 3.50 mm | E/4 | 9 |
| 4.00 mm | G/6 | 8 |
| 4.50 mm | 7 | 7 |
| 5.00 mm | H/8 | 6 |
| 5.50 mm | I/9 | 5 |
| 6.00 mm | J/10 | 4 |
| 6.50 mm | K/10.5 | 3 |
| 8.00 mm | L/11 | 0 |
| 9.00 mm | M/N-13 | 00 |
| 10.00 mm | N/P-15 | 000 |
Tip: Metric (mm) is the most reliable. Always trust the millimeter size when possible.
3. How to Choose the Right Crochet Hook Size
Your hook size depends on:
a. Yarn Weight
Every yarn label recommends a hook size range.
Examples:
-
DK yarn: 4.0 mm – 4.5 mm
-
Worsted yarn: 5.0 mm – 5.5 mm
-
Bulky yarn: 6.0 mm – 7.0 mm
b. Project Type
-
Tighter fabric → smaller hook
-
Looser drape → larger hook
c. Your Crochet Tension
Everyone crochets differently.
If your stitches are tight → go up a size.
If your stitches are loose → go down a size.
4. Yarn Weight & Hook Size Matching Chart
| Yarn Weight Category | Common Name | Recommended Hook Size |
|---|---|---|
| 0 | Lace | 1.5 – 2.25 mm |
| 1 | Super Fine | 2.25 – 3.25 mm |
| 2 | Fine | 3.25 – 4.0 mm |
| 3 | Light (DK) | 4.0 – 4.5 mm |
| 4 | Medium (Worsted) | 5.0 – 6.0 mm |
| 5 | Bulky | 6.0 – 8.0 mm |
| 6 | Super Bulky | 8.0 – 12.0 mm |
| 7 | Jumbo | 12.0 mm+ |
5. Signs You’re Using the Wrong Hook Size
You may need to adjust your hook if:
❌ Fabric is too stiff
❌ Stitches look uneven
❌ Project is much smaller/larger than expected
❌ Hands feel strained while crocheting
6. FAQ for Beginners
Q: Can I use a different hook size than the pattern?
Yes—but it will change the size and drape of your project.
Q: What size hook is best for beginners?
Most beginners start with a 5.0 mm (H/8) because it works well with worsted-weight yarn and is easy to control.
Q: Do expensive hooks matter?
Not necessarily. Comfort and smoothness matter more than price.
Conclusion
Understanding crochet hook sizes is essential for creating neat, consistent projects. With this simple conversion guide and yarn weight chart, you’ll be able to choose the right hook every time—no more confusion between US and UK sizes.