Emergency Use of S.A.E. (American) Wrenches On Metric Fasteners

Though this is not a recommneded process, some American standard wrenches can be used in an emergency for metric nuts and bolts.
Metric Size U.S. Size Comments Metric to U.S. Ratio
7mm 5/16" [Extremely loose] 113%
8mm 5/16" [Tight] 99%
9mm 11/32" [Too tight unless head is damaged] 97%
10mm 7/16" [Extremely loose] 111%
11mm 7/16" [Very good] 101%
12mm 1/2" [Very loose] 106%
13mm 1/2" [Too tight unless head is damaged] 98%
14mm 9/16" [Loose] 102%
15mm 19/32" [Very good] 101%
17mm 11/16" [Loose] 103%
19mm 3/4" [Perfect] 100%
22mm 7/8" [Slightly loose] 101%
25mm 1" [Loose] 102%
27mm 1-1/16" [Perfect] 100%
30mm 1-3/16" [Slightly loose] 101%
36mm 1-7/16" [Slightly loose] 101%

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