Crochet hook sizes

Metric against the US letter-number and the UK number, with the steel sizes for thread at the foot. The last column says which of the patterns here calls for each.

Crochet hook sizes, metric against US and UK
Metric mm	US letter or number	UK number	Used by patterns here
2.25	B/1	13	not called for here
2.5	-	12	not called for here
2.75	C/2	-	not called for here
3.0	-	11	Cat Claws Granny Square, Duck Granny Square, Puff Stitch Sunflower Granny Square, Two-Color Basic Granny Square, Diagonal Two-Color Solid Granny Square, Cherry Blossom Granny Square, Unique Window Flower Granny Square
3.25	D/3	10	not called for here
3.5	E/4	9	not called for here
3.75	F/5	-	not called for here
4.0	G/6	8	Easy crochet bolero pattern for girls, Crochet Scented Sachet Bag Pattern - Perfect for Gifting, Sunburst Granny Square
4.5	7	7	not called for here
5.0	H/8	6	Easy crochet bolero pattern for girls, Crochet Scented Sachet Bag Pattern - Perfect for Gifting
5.5	I/9	5	not called for here
6.0	J/10	4	not called for here
6.5	K/10.5	3	not called for here
7.0	-	2	not called for here
8.0	L/11	0	not called for here
9.0	M-N/13	00	not called for here
10.0	N-P/15	000	not called for here
12.0	-	-	not called for here
15.0	P/Q	-	not called for here
16.0	Q	-	not called for here
19.0	S	-	not called for here
1.65	-	7	not called for here
1.5	-	8	not called for here
1.4	-	9	not called for here
1.25	-	10	not called for here
1.0	-	12	not called for here

How the last column was filled in

A millimetre figure counts as a hook only when the line it sits on also says the word hook. Without that rule an 11 mm pair of safety eyes in a toy's materials list files that toy under an 11 mm hook, which is nonsense, and the kind of nonsense a reader would not spot. Anything the sources left vague stays out of the column.

There is no hook filter on the patterns page for the same reason: the source text does not carry a reliable hook size on every pattern, and a filter that quietly drops 8 of the 18 is worse than no filter.