Needle Conversion Chart Thanks to Anne R. US Metric UK 0 2 mm 14 1 2.25 mm 13 2.5 mm 2 2.75 mm 12 3 mm 11 3 3.25 mm 10 4 3.5 mm 5 3.75 mm 9 6 4 mm 8 7 4.5 mm 7 8 5 mm 6 9 5.5 mm 5 10 6 mm 4 10.5 6.5 mm 3 7 mm 2 7.5 mm 1 11 8 mm 0 13 9 mm 00 15 10 mm 000 Through US 10, if you subtract the US size from 14, you get the UK equivalent.
