Whats is the mm equivalent of US / old UK knitting needles?
Here's an overview of all the knitting needle sizes I know.


Metric    UK        US
0.5mm     24        -
0.75mm    22        -
1.0mm     20        5/0
1.25mm    18        4/0
1.5mm     17        000
1.625mm   16        -
1.75mm    15        00
2.0mm     14        0
2.25mm    13        1
2.5mm     -         1.5
2.75mm    12        2
3.0mm     11        2.5
3.25mm    10        3
3.5mm     -         4
3.75mm    9         5
4.0mm     8         6
4.5mm     7         7
5.0mm     6         8
5.5mm     5         9
6.0mm     4         10
6.5mm     3         10.5
7.0mm     2         -
7.5mm     1         -
8.0mm     0         11
9.0mm     00        13
10.0mm    000       15
12.0mm    -         17
15.0mm    -         19
20.0mm    -         35
50.0mm    -         50


For crochet hooks, see: What is the conversion for UK and US crochet hooks to mm?