SAE and Metric Wrench and Socket Size Reference

Size	Type	Size (mm)	Notes on Approximate Matches
6 mm	Metric	6.00	Close to 1/4 inch (0.35 mm difference)
1/4 inch	SAE	6.35	Close to 6 mm (0.35 mm difference)
7 mm	Metric	7.00
8 mm	Metric	8.00	Close to 5/16 inch (0.0625 mm difference)
5/16 inch	SAE	7.9375	Close to 8 mm (0.0625 mm difference)
11/32 inch	SAE	8.73125
9 mm	Metric	9.00
3/8 inch	SAE	9.525	Close to 10 mm (0.475 mm difference)
10 mm	Metric	10.00	Close to 3/8 inch (0.475 mm difference)
11 mm	Metric	11.00	Close to 7/16 inch (0.1125 mm difference)
7/16 inch	SAE	11.1125	Close to 11 mm (0.1125 mm difference)
12 mm	Metric	12.00
1/2 inch	SAE	12.7	Close to 13 mm (0.3 mm difference)
13 mm	Metric	13.00	Close to 1/2 inch (0.3 mm difference)
14 mm	Metric	14.00
9/16 inch	SAE	14.2875
15 mm	Metric	15.00
5/8 inch	SAE	15.875	Close to 16 mm (0.125 mm difference)
16 mm	Metric	16.00	Close to 5/8 inch (0.125 mm difference)
17 mm	Metric	17.00
11/16 inch	SAE	17.4625
18 mm	Metric	18.00
19 mm	Metric	19.00	Approximately the same as 3/4 inch (0.05 mm difference)
3/4 inch	SAE	19.05	Approximately the same as 19 mm (0.05 mm difference)
20 mm	Metric	20.00
21 mm	Metric	21.00	Close to 13/16 inch (0.3625 mm difference)
13/16 inch	SAE	20.6375	Close to 21 mm (0.3625 mm difference)
22 mm	Metric	22.00	Close to 7/8 inch (0.225 mm difference)
7/8 inch	SAE	22.225	Close to 22 mm (0.225 mm difference)
15/16 inch	SAE	23.8125	Close to 24 mm (0.1875 mm difference)
24 mm	Metric	24.00	Close to 15/16 inch (0.1875 mm difference)
1 inch	SAE	25.4
1-1/16 inch	SAE	26.9875	Approximately the same as 27 mm (0.0125 mm difference)
27 mm	Metric	27.00	Approximately the same as 1-1/16 inch (0.0125 mm difference)
1-1/8 inch	SAE	28.575
30 mm	Metric	30.00
1-1/4 inch	SAE	31.75	Close to 32 mm (0.25 mm difference)
32 mm	Metric	32.00	Close to 1-1/4 inch (0.25 mm difference)