Guide
AN fitting sizes: dash size chart
An AN dash size is the tube outside diameter in sixteenths of an inch: -6 AN is 6/16 = 3/8 in. The chart below gives the thread, the male thread diameter to check with calipers, the AN port O ring and the braided hose ID for every size from -2 to -32.
AN dash size chart
Threads are UNF or UN, class 3A male and 3B female. Ratings are nominal working pressures for steel fittings at room temperature; aluminum and the hose or tube can rate lower.
| Dash size | Tube OD | Thread | Male thread OD | AN port O ring | Rubber AN hose ID | PTFE AN hose ID | Rated to (steel) |
|---|---|---|---|---|---|---|---|
| -2 AN | 1/8 in (3.17 mm) | 5/16-24 UNF | .3125 in (7.94 mm) | AS568-902 | – | – | 5,000 psi |
| -3 AN | 3/16 in (4.76 mm) | 3/8-24 UNF | .375 in (9.52 mm) | AS568-903 | – | .13 in | 5,000 psi |
| -4 AN | 1/4 in (6.35 mm) | 7/16-20 UNF | .4375 in (11.11 mm) | AS568-904 | .22 in | .19 in | 5,000 psi |
| -5 AN | 5/16 in (7.94 mm) | 1/2-20 UNF | .5 in (12.7 mm) | AS568-905 | – | – | 5,000 psi |
| -6 AN | 3/8 in (9.52 mm) | 9/16-18 UNF | .5625 in (14.29 mm) | AS568-906 | .34 in | .31 in | 5,000 psi |
| -8 AN | 1/2 in (12.7 mm) | 3/4-16 UNF | .75 in (19.05 mm) | AS568-908 | .44 in | .41 in | 4,500 psi |
| -10 AN | 5/8 in (15.88 mm) | 7/8-14 UNF | .875 in (22.22 mm) | AS568-910 | .56 in | .5 in | 3,500 psi |
| -12 AN | 3/4 in (19.05 mm) | 1 1/16-12 UN | 1.0625 in (26.99 mm) | AS568-912 | .69 in | .62 in | 3,500 psi |
| -16 AN | 1 in (25.4 mm) | 1 5/16-12 UN | 1.3125 in (33.34 mm) | AS568-916 | .88 in | – | 3,000 psi |
| -20 AN | 1 1/4 in (31.75 mm) | 1 5/8-12 UN | 1.625 in (41.27 mm) | AS568-920 | – | – | 2,500 psi |
| -24 AN | 1 1/2 in (38.1 mm) | 1 7/8-12 UN | 1.875 in (47.63 mm) | AS568-924 | – | – | 2,000 psi |
| -32 AN | 2 in (50.8 mm) | 2 1/2-12 UN | 2.5 in (63.5 mm) | AS568-932 | – | – | 1,500 psi |
Reading a dash size
Divide the dash number by 16 for the tube OD in inches: -4 is 1/4 in, -10 is 5/8 in, -16 is 1 in. Hose is sized to fit the same fitting, so its inside diameter is a little under the tube OD, and PTFE hose runs smaller than rubber hose of the same dash size.
Measuring a fitting
Put calipers across the male threads and find the nearest male thread OD in the chart, then count the threads in one inch. A 0.56 in thread with 18 threads per inch is 9/16-18, which is -6. Look at the seat as well: a 37° cone is AN or JIC, a 45° cone is SAE flare.
AN, JIC and SAE 45°
AN and JIC share the 37° seat and the thread, so they mate. SAE 45° flare has the same thread in some sizes but a different seat, so it will thread on and still leak. INV inverted flare on brake lines needs an adapter.
AN ports
An AN port on a pump, filter or fuel rail is an ORB port: the same thread as the AN fitting, sealed by the O ring in the chart rather than a flare. Use a male ORB end, not a male AN flare, in an AN port.
Typical sizes on a car
-3 for brake lines, -4 for turbo oil feeds and gauges, -6 and -8 for fuel feed and return, -10 and -12 for oil coolers, turbo drains and dry sump lines, -16 and up for coolant. Size each line for its flow.
AN fitting questions
What does -6 AN mean?
The dash number is the tube outside diameter in sixteenths of an inch. -6 AN is for 6/16 = 3/8 in tube, and its fittings use a 9/16-18 UNF thread.
Is AN the same as JIC?
They share the 37° flare seat and the same UNF threads, so a -6 AN and a -6 JIC screw together and seal. AN parts are made to tighter class 3A and 3B threads and military or aerospace standards; JIC uses class 2A and 2B for hydraulics.
What size is -8 AN?
-8 AN is for 1/2 in (12.7 mm) tube or hose, with a 3/4-16 UNF thread that measures about .75 in (19.05 mm) across the male threads.
Is an AN port the same as an AN fitting?
No. An AN port is an O ring boss (ORB) port: the same thread as the AN fitting of that dash size, but it seals with an O ring in a chamfer instead of a 37° flare. A -6 AN port takes a -6 ORB male end.
Do AN fittings fit NPT or SAE 45° flare?
Not directly. NPT is a tapered pipe thread and SAE 45° flare has a different seat angle, so they need an adapter, for example AN to NPT.
How do I measure an AN fitting?
Measure across the male threads with calipers and match it to the male thread OD column, then count threads per inch. Check the seat: AN and JIC are 37°, SAE flare is 45°.
Need an AN fitting that does not exist?
Pick any AN size on one end and any thread on the other, in aluminum, steel or stainless, and see the price before you order.
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