There are many factors associated with a knitting needle:

• Type (straight, double-pointed, circular cable, etc.)
• Length (length of needle, length of cable, length of tip, etc.)
• Material (aluminum, wood, plastic, etc.)
• Size (diameter of the needle shaft)

The following shows the sizes of standard knitting needles.

The global standard for size is metric, although many patterns still call for needle sizes in local sizing formats.

Knitting Needle Size Comparison Chart - Gauge, Millimeter, US, UK

Metric Diameter (millimeter, millimetre, mm	US Size	UK Size
2.00 mm	0	14
2.25 mm	1	13
2.75 mm	2	12
3.00 mm	2.5	11
3.25 mm	3	10
3.50 mm	4	-
3.75 mm	5	9
4.00 mm	6	8
4.50 mm	7	7
5.00 mm	8	6
5.50 mm	9	5
6.00 mm	10	4
6.50 mm	10.5	3
7.00 mm	-	2
7.50 mm	-	1
8.00 mm	11	0
9.00 mm	13	0
10.00 mm	15	0
12.00 mm	17	-
20.00 mm	35	-
25.00 mm	50	-

The Standard Description of Knitting Needle Sizes should be in millimeters (based on the diameter of the needle)