Inches
Millimetres
Spanner
0.250
1/4 AF
0.276
7mm
7mm
0.313
5/16 AF
0.315
8mm
8mm
0.344
11/32 AF; 1/8 Wworth
0.354
9mm
9mm
0.375
3/8 AF
0.394
10mm
10mm
0.433
11mm
11mm
0.438
7/16 AF
0.445
3/16 Wworth; 1/4
0.472
12mm
12mm
0.500
1/2 AF
0.512
13mm
0.525
1/4 Wworth; 5/16 BSF
0.551
14mm
0.563
9/16 AF
0.591
15mm
0.600
5/16 Wworth; 3/8 BSF
0.625
5/8 AF
0.630
16mm
16mm
0.669
17mm
17mm
0.686
11/16 AF
0.709
18mm
18mm
0.710
3/8 Wworth; 7/16 BSF
0.748
19mm
19mm
0.750
3/4 AF
0.787
20mm
20mm
0.813
13/16 AF
0.820
7/16 Wworth; 1/2 BSF
0.826
21mm
21mm
0.866
22mm
22mm
0.875
7/8 AF
0.905
23mm
23mm
0.920
1/2 Wworth; 9/16 BSF
0.938
15/16 AF
0.945
24mm
24mm
0.984
25mm
25mm
1.000
1in AF
1.010
9/16 Wworth; 5/8 BSF
1.024
26mm
26mm
1.063
27mm
1 1/16 AF; 27mm
1.100
5/16 Wworth; 11/16 BSF
1.125
1 1/8 AF
1.181
30mm
30mm
1.200
11/16 Wworth; 3/4 BSF
1.250
1 1/4 AF
1.260
32mm
32mm
1.300
3/4 Wworth; 7/8 BSF
1.313
1 5/16 AF
1.390
13/16 Wworth; 15/16 BSF
1.417
36mm
36mm
1.418
1 7/16 AF
1.480
7/8 Wworth; 1in BSF
1.500
1 1/2 AF
1.575
40mm
15/16 AF; 40mm exactly
1.614
41mm
41mm
1.625
1 5/8 AF
1.670
1 in Wworth; 1 1/8 BSF
1.688
1 11/16 AF
1.811
46mm
46mm
1.813
1 13/16 AF
1.860
1 1/8 Wworth; 1 1/4 BSF
1.875
1 7/8 AF
1.969
50mm
50mm
2.000
2in AF
2.050
1 1/4 Wworth; 1 3/8 BSF
2.165
55mm
55mm
2.362
60mm
60mm