AN Fitting Tech

MALE AN ADAPTER IDENTIFICATION CHART
The line drawings to the right depict actual sizes of the various common AN thread sizes by dash number. Lay your fitting over the appropriate drawing to determine what size fitting you have.
PIPE THREAD SIZE CHART
Use the diagram to the right to find pipe thread size. Place fitting against base line; read fitting size where it intersects the vertical line.
AN SIZE METAL TUBE O.D. THREAD SIZE
-3 3/16″ 3/8″ – 24 SAE
-4 1/4″ 7/16″ – 20 SAE
-5 5/16″ 1/2″ – 20 SAE
-6 3/8″ 9/16″ – 18 SAE
-8 1/2″ 3/4″ – 16 SAE
-10 5/8″ 7/8″ – 14 SAE
-12 3/4″ 1-1/16″ – 12 SAE
-16 1″ 1-5/16″ – 12 SAE
-20 1- 1/4″ 1-5/8″ – 12 SAE
B-NUT SIZE CHART
The line drawings to the right depict actual sizes of the various common types of fittings, hose ends and adapters. The number in parenthesis is SAE wrench size equivalent.
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Source: http://www.russellperformance.com/misc/tech/main.shtml