Does your knitting pattern call for knitting needles of 4 mm and you have a US 4 and you wonder if it’s the same or different? The answer is that they are different. The world, though united in love for knitting, is divided by different number systems. This has happened to every knitter, especially when they are new. However, the most important lesson is that every knitting needle size has a purpose. The yarn weight, project and gauge directly affect the needle size. All knitting needles are labeled with sizes, but the challenge arises with the difference between the European and US sizing systems. Once you understand the difference and how to convert knitting needle sizes, you will crack the code for which needle is best.
Why Knitting Needle Sizes Differ
Knitting needle sizes are determined by the diameter of the needle shaft, whether its single-pointed, double-pointed, fixed, or interchangeable circulars. Refer to our guide on knitting needle sizes to dive into the details. However, the labeling systems vary. It is important to pay attention to which size you reference because a US 5 and 5mm are very different sizes.
- European Sizes – Typically measured in millimeters (mm), reflecting the exact diameter of the needle. This system is straightforward and universally recognized in most countries outside North America.
- US Sizes – Labeled with a number scale rather than millimeters. The US sizing system dates back to earlier manufacturing standards and does not correspond linearly to millimeter measurements. In US measurement, the smaller the number, the smaller the needle size.
- UK/ Canadian Sizes- Labeled with a number scale similar to US sizes; however, here the larger numbers depict the smaller sizes, while the smallest numbers represent the bigger needle sizes.
If you only go by numbers without checking the mm measurement, you might pick the wrong size, leading to a mismatched gauge. The ultimate guide to knitting needles helps you know about types, lengths, uses and everything you need to know.
Knitting Needle Size Conversion Chart
| Metric (mm) |
US Size |
UK/Canadian Size |
|
2.0 mm |
0 |
14 |
|
2.25 mm |
1 |
13 |
|
2.75 mm |
2 |
12 |
|
3.0 mm |
2.5 |
11 |
|
3.25 mm |
3 |
10 |
|
3.5 mm |
4 |
— |
|
3.75 mm |
5 |
9 |
|
4.0 mm |
6 |
8 |
|
4.5 mm |
7 |
7 |
|
5.0 mm |
8 |
6 |
|
5.5 mm |
9 |
5 |
|
6.0 mm |
10 |
4 |
|
6.5 mm |
10.5 |
3 |
|
7.0 mm |
10.75 |
2 |
|
7.5 mm |
— |
1 |
|
8.0 mm |
11 |
0 |
|
9.0 mm |
13 |
0 |
|
10.0 mm |
15 |
0 |
|
12.0 mm |
17 |
— |
|
16.0 mm |
19 |
— |
|
19.0 mm |
35 |
— |
|
25.0 mm |
50 |
— |
Tip: Always check the mm marking on the needle itself, as it is the most accurate measurement regardless of country of origin.
Knitting Needle Sizes Explained
12mm – 25mm/ US 17 AND UP - Pairs with jumbo/ bulky yarns that are great for weighted blankets and other large projects. Knitting with needles this big is a serious arm workout. When shopping for needles this size, opt for light materials.
8mm- 12mm/ US 11-17 - These sizes pair with chunky yarns as they are typically quick-knit projects. After size 11, there are only odd sizes, so don't look for a size 12 or 14, because you won't find it.
5.5mm - 8mm/ US 9-11 - These needles are still pretty large and work well for large projects with heavyweight yarn.
4.5mm -5.5mm /US 7-9 - This size range is usually the size that beginner knitters learn to use first. These needles are very manageable and great for worsted-weight yarn. Many sweater and hat patterns call for knitting needles in this size range.
3.75mm - 4.5mm /US 5-7 - Another common size for knitting sweaters, scarves, and gloves, these needles go hand in hand with DK weight yarn.
US 3-5 - Knitters who enjoy knitting garments for babies typically use these needles. Sport weight yarn pairs well with these needles to craft socks, sweaters, baby blankets and baby layettes. As we head down in needle size, you may experience some hand discomfort. Take a few moments to stretch your fingers a bit.
US 1-3 - Known as the sock knitting needles, this size range is ideal for sock-weight yarn. Socks, shawls, and any lightweight garment pattern will require this range of needle size.
US 000-1 - If you are just starting out, you won't need this size needle until you gain some experience. These tiny needles are for lace patterns and other very tiny and precise stitching. These needles are considered to be specialized and require dexterity and lots of patience.
Why Correct Needle Sizing Matters
Choosing the correct needle size is more than a technicality; it affects the gauge and fit of the project. Even a 0.25mm difference can change your stitch count, altering the size of garments and accessories. Take, for example, if that pattern calls for 4mm needles and you mistakenly use 4.5mm (US 7), your stitches will be larger, and the hat may come out too loose. The yarn usage also differs and the drape is also altered. The recommended method to always get the right count is working with a knitting needle sizer. They are a handy accessory that helps you identify the size and also calculate gauge. Refer to our blog on why and how to use knitting needle sizers.
Common Mistakes in Needle Size Conversion
When switching between European knitting needle sizes and US sizes, avoid these common errors:
- Relying Only on the Number – Always check the mm measurement; US or even UK/ Canadian numbers can be misleading.
- Not Swatching – Even with the correct size, your personal knitting tension may require adjustments. So, start with a gauge swatch.
- Overlooking Vintage Patterns – Older US patterns may use outdated sizing references.
With this guide, you have all the information you need to tackle problems that arise due to knitting needle sizes. However, it’s recommended to have a conversion chart in your toolkit and a needle gauge tool with both metric and US sizes, and a little practice, you’ll never have to second-guess your needle choice again.
Choose from the KnitPro collection for the widest range of knitting needles in standard sizes mentioned in both metric and US measurements.
