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AN Fitting Size Chart
AN dash numbers converted to nominal tube size and outside diameter. The dash number is the tube outside diameter in sixteenths of an inch.
| AN size | Tube OD | Millimetre (mm) |
|---|
Standard: SAE J514 · Data checked: 2026-10-14
Frequently asked questions
What does the dash number mean?
It is the tube outside diameter in sixteenths of an inch. A -6 fitting is for 6/16 in tube, which is 3/8 in. So a -4 is 1/4 in tube and a -8 is 1/2 in. That is why AN sizes step in even numbers for the common sizes.
Are AN and JIC the same thing?
The 37 degree flare fitting is common to both, and in practice the terms are used interchangeably for that style. AN is the military standard with tighter tolerances and inspection requirements; JIC is the industrial equivalent. For most work they are dimensionally compatible.
Can I mix AN and NPT?
No. NPT is a tapered pipe thread that seals on the threads; AN is a straight thread that seals on a 37 degree flare or an O-ring. They are not interchangeable and forcing one into the other damages the fitting. Use the correct adapter.
How tight should an AN fitting be?
Snug plus a small amount, not torqued hard. The flare does the sealing, so overtightening distorts it and causes leaks. Specific torque figures exist per size, and they are modest — the common failure mode on AN fittings is overtightening, not undertightening.