Conversion

Size chart

ISO-aligned inner diameter and circumference. Your current size is marked. Swipe the table sideways for millimetres.

US	UK	ISO	JP	Diameter	Circumference
3	F	44.2	4	14.07 mm	44.20 mm
3.5	G½	45.5	6	14.48 mm	45.50 mm
4	H½	46.8	7	14.88 mm	46.80 mm
4.5	I½	48	8	15.29 mm	48.00 mm
5	J½	49.3	9	15.70 mm	49.30 mm
5.5	K½	50.6	10	16.10 mm	50.60 mm
6	L½	51.9	12	16.51 mm	51.90 mm
6.5	M½	53.1	13	16.92 mm	53.10 mm
7	N½	54.4	14	17.32 mm	54.40 mm
7.5	O½	55.7	15	17.73 mm	55.70 mm
8	P½	57	16	18.14 mm	57.00 mm
8.5	Q½	58.3	17	18.54 mm	58.30 mm
9	R½	59.5	18	18.95 mm	59.50 mm
9.5	S½	60.8	19	19.35 mm	60.80 mm
10	T½	62.1	20	19.76 mm	62.10 mm
10.5	U½	63.4	22	20.17 mm	63.40 mm
11	V½	64.6	23	20.57 mm	64.60 mm
11.5	W½	65.9	24	20.98 mm	65.90 mm
12	X½	67.2	25	21.39 mm	67.20 mm
12.5	Z	68.5	26	21.79 mm	68.50 mm
13	Z+1	69.7	27	22.20 mm	69.70 mm
13.5	Z+2	71	28	22.61 mm	71.00 mm
14	Z+3	72.3	29	23.01 mm	72.30 mm
14.5	Z+4	73.6	30	23.42 mm	73.60 mm
15	Z+5	74.8	31	23.83 mm	74.80 mm
15.5	Z+6	76.1	32	24.23 mm	76.10 mm
16	Z+7	77.4	33	24.64 mm	77.40 mm

Showing diameters in millimetres. Switch units on the Size tab. Highlight follows US 7 (US).