2025.03.23

Sockets and Spanners

The information below is based on the best available information, but may, in some circumstances not be correct. The user of this page is encouraged to personally verify the information below. If you have additional information to add or corrections to the information below, please send an e-mail to “bob” at “jagnuts.ca”.

Nut Size Across Flats			British Sizes
decimal inch	mm	AF inch	BA	BSF	BSW

0.2500	–	1/4	–	–	–
0.2756	7	–	–	–	–
0.2820	–	–	3	–	–
0.3125	–	5/16	–	–	–
0.3150	8	–	–	–	–
0.3240	–	–	2	–	–
0.3400	–	–	–	3/16	1/8
0.3438	–	11/32	–	–	–
0.3543	9	–	–	–	–
0.3650	–	–	1	–	–
0.3750	–	3/8	–	–	–
0.3937	10	–	–	–	–
0.4120	–	–	0	–	–
0.4331	11	–	–	–	–
0.4375	–	7/16	–	–	–
0.4450	–	–	–	1/4	3/16
0.4724	12	–	–	–	–
0.5000	–	1/2	–	–	–
0.5118	13	–	–	–	–
0.5250	–	–	–	5/16	1/4
0.5512	14	–	–	–	–
0.5625	–	9/16	–	–	–
0.5906	15	–	–	–	–
0.6000	–	–	–	3/8	5/16
0.6250	–	5/8	–	–	–
0.6299	16	–	–	–	–
0.6693	17	–	–	–	–
0.6875	–	11/16	–	–	–
0.7087	18	–	–	–	–
0.7100	–	–	–	7/16	3/8
0.7480	19	–	–	–	–
0.7500	–	3/4	–	–	–
0.7874	20	–	–	–	–
0.8125	–	13/16	–	–	–
0.8200	–	–	–	1/2	7/16
0.8661	22	–	–	–	–
0.8750	–	7/8	–	–	–
0.9200	–	–	–	9/16	1/2
0.9375	–	15/16	–	–	–
0.9449	24	–	–	–	–
1.0000	–	1	–	–	–
1.0625	–	1 1/16
1.1250	–	1 1/8
1.2500	–	1 1/4
1.3125	–	1 5/16
1.3750	–	1 3/8
1.5000	–	1 1/2