Often when we are knitting a garment, we ask, often in a fury of rage as the sleeve fits our waist measurement: “Why the *$%^# can’t everyone just get along and use the same needle gauge?” Well, since knitting has evolved in so many different cultures, it is obvious that knitting needle gauge and yarn weight have been a place of independent creation for different nations for many hundreds of years. There are no two that match identically and for the most part, each system listed in the conversion chart below appear entirely irrational next to their cousins. This is why we have conversion charts! It allows us to work with other peoples patterns and needles.  In the west, there has been a growing interest in Japanese patterns and stitch dictionaries, so I included what I could find about their needle sizing system.

One interesting point is that we can derive what size needles are most commonly used by a nation if we look at the section of the conversion chart where the sizing increments are closest together. For us in Canada, that the range between 2.5 and mm-4.5mm.

Metric*	US	UK	Japanese
0.50mm	8/0	24	-
0.75mm	6/0	22	-
0.82mm	-	20	-
1.00mm	5/0	19	-
1.25mm	4/0	18	-
1.50mm	000	17	-
1.75mm	00	15	-
2.00mm	0	14	-
2.10mm	-	-	0
2.25mm	1	13	0
2.40mm	-	-	1
2.50mm	-	-	-
2.70mm	-	-	2
2.75mm	2	12	-
3.00mm	-	11	3
3.25mm	3	10	-
3.30mm	-	-	4
3.50mm	4	-	-
3.60mm	-	-	5
3.75mm	5	9	-
3.90mm	-	-	6
4.00mm	6	8	-
4.20mm	-	-	7
4.50mm	7	7	8
4.80mm	-	-	9
5.00mm	8	6	-
5.10mm	-	-	10
5.40mm	-	-	11
5.50mm	9	5	-
5.70mm	-	-	12
6.00mm	10	4	13
6.30mm	-	-	14
6.50mm	10.5	3
6.60mm	-	-	15
7.00mm	-	2	7.00mm
7.50mm	-	1	-
8.00mm	11	0	8.00mm
9.00mm	13	00	9.00mm
10.0mm	15	000	10.0mm
12.50mm	17	-	-
14.00mm	18	-	-
15.50mm	19	-	-
19.00mm	35	-	-
25.00mm	50	-	-

*since metric is also a standard measurement, so I used it to show the measurements of all needles regardless of whether the needle size is common in Canada or not. Standard needle sizes in the metric column are bold.

*I have cobbled this chart together using several sources, which I have listed on my glossary page.

Now for yarn weight.  Yarn comes in a variety of different weights from nearly as thin as human hair, to as wide as a human finger (or larger!). Yarns are categorized by their number of stitches per 4 inch (10cm) swatch of stockinette stitch fabric on the recommended needle size.

Classification	Yarns	Stitches	Recommended Needle Size
0 – Lace	Cobweb, Lace	33-40 sts	1.5 – 2.25 mm
1 – Super Fine	Sock, Fingering	27-32 sts	2.25 – 3.25 mm
2 – Fine	Sport	23-26 sts	3.25 – 3.75 mm
3 -  Light	DK, Light Worsted	21-24 sts	3.75 – 4.5 mm
4 – Medium	Worsted, Afgan, Aran	16-20 sts	4.5 – 5.5 mm
5 – Bulky	Chunky, Craft, Rug	12-15 sts	5.5 – 8 mm
6 – Super Bulky	Bulky, Roving	6-11 sts	8mm +

*Chart according to the Yarn Craft Council Standard Yarn Weights

That being said, needle size in relation to yarn weight is rather arbitrary. I recall Elizabeth Zimmermann doing a continuous gauge swatch of a certain yarn weight that she had purchased. She used every needle size that she had, and each needle combined with the same yarn created a different fabric. For example, one could knit cobweb weight yarn with 0.5mm needles and end up with a fairly dense fabric.  It would take forever, and a ton of yarn but the fabric would be delicate and the detail exquisite.  The point is that the knitter has to understand the desired fabric well enough to be able to judge according to their knitting style, tension, yarn, fiber and needle choice, which of each to choose. This takes time.  THIS is why gauge swatches are important (and detested).

The most important point to remember from all of this knitting geek speak, is that you need to be able to get gauge (that’s the part where they say ” blah blah 33 stitches over 4″ of stockinette).  As long as you get gauge, you can use whatever needle you need.  Do not feel constrained by the recommended needle size, use it only as a starting point. Oh and don’t forget to wash and block your swatch.  Just saying.