Knitting and the Metric System

The United States is one of the remaining few countries that haven’t fully switched over to the Metric system, but with modern globalization, I believe it will only be a matter of time before that happens. In a lot of ways, I think the Metric system makes more sense, but I also know a full conversion would be difficult to say the least. I don’t think in meters or grams, and I don’t think many other people in the United States do either. At the same time, I constantly have to look up how many cups are in a gallon or how many ounces are in a cup, so I understand why this conversion is needed.  With the metric system, all of those conversions are much simpler because everything is based on factors of 10.


Knitting is one of the few areas of my life where I regularly come across metric sizing. While needle sizing and patterns usually include both measurements, there are times when I have to convert back to the US system because the pattern designer only uses metric measurements, and I can’t easily think in millimeters or centimeters. The conversion is fairly easy, with 1 inch = 2.54 cm, but I have recently started to get annoyed with using the US system for needle sizing because the conversion is not as simple.


IN the United States, the numbers that indicate needle sizes are basically arbitrary, indicating nothing more than that if you have a smaller number, you have a smaller needle. They are standardized to the Metric system, which is great, but why we don’t just use the actual metric sizing when we talk about needles is beyond me. I automatically began thinking of needles in the US sizing when I began knitting, and even though the Metric sizes are almost always listed in conjunction with the US sizes, it is still difficult for me to convert my thinking. Because of this, I decided that might help to begin memorizing the metric sizes for needles to make my knitting life a little easier. When you actually take time to compare the metric sizes to one another, it is a very consistent progression, and I’ve found that it has strengthened my understanding of needle sizes.


To help, I made an accessible PDF of Metric/US conversions that are relevant to knitting and crochet which you can download here if it would be helpful for you. For convenience, the information in the PDF is also included below.




Quick Length Conversion


1 inch = 2.54 Centimeters


Divide centimeters given by 2.54 to determine inches.


Multiply inches given by 2.54 to determine centimeters.




Knitting Needle Sizes



US Sizes Metric Sizes
0 2 mm
1 2.25 mm
1.5 2.5 mm
2 2.75 mm
2.5 3 mm
3 3.25 mm
4 3.5 mm
5 3.75 mm
6 4 mm
7 4.5 mm
8 5 mm
9 5.5 mm
10 6 mm
10.5 6.5 mm
10.75 7 mm
11 8 mm
13 9 mm
15 10 mm





Crochet Hook Sizes



Note that some brands might vary slightly, so be sure to check the sizing for your particular brand of hook for accuracy.


US Sizes Metric Sizes
B 2.25 mm
C 2.75 mm
D 3.13 mm
E 3.5 mm
F 3.75 mm
G 4 mm
H 5 mm
I 5.5 mm
J 6 mm
K 6.5 mm
L 8 mm
M 9 mm
N 10 mm




1 Comment (+add yours?)

  1. Trackback: Review: Easy-read Row Counters and Needle Gauges | Working out Kinks and Fingering Yarn

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