AN Fitting Size Calculator
Select any AN dash size to get the full specification — bore ID, thread spec, hex wrench size, flow capacity, working pressure, and compatible hose types. Reference table included for every size from AN-3 to AN-20.
Full Dimensional Data
Bore ID, hose OD, thread OD, hex wrench size — in both metric and imperial.
Pressure Ratings
Working pressure for aluminium and steel fittings with 4:1 safety factor reference.
Flow Capacity
Approximate max flow rate (LPH / GPH) to help size your fuel or oil system correctly.
Cross-Section Visual
To-scale bore and hose OD diagram compared against AN-20 for an instant size feel.
Thread: 9/16-18 UNF
Hex wrench: 22mm / 7/8"
Bore ID
9.53 mm
0.3750" / 375 thou
Hose OD
15.9 mm
0.626"
Thread OD
14.288 mm
0.5625"
Hex Size
22 mm
7/8"
Cross-Section
71.3 mm²
0.1104 in²
Bore Ratio vs AN-20
30.0%
of AN-20 bore area
Flow Area Ratio
9.0%
of AN-20 flow area
Thread Pitch
18
threads per inch (UNF)
Flow Capacity (Reference)
Fuel @ 50 PSI reference — actual varies with fluid viscosity & line length
Cross-Section (to scale vs AN-20)
Working Pressure by Material
Working pressure is 4:1 safety factor below burst. Always verify with manufacturer datasheet for safety-critical applications.
Compatible Hose Types
Typical Applications
Full AN Dash Size Reference Table
| Dash | Bore ID (mm) | Bore ID (in) | Thread | Hex | Flow (LPH) | WP Alum (PSI) |
|---|---|---|---|---|---|---|
| AN-3 | 4.76 | 0.1875 | 3/8-24 UNF | 14mm | 95 | 2,000 |
| AN-4 | 6.35 | 0.2500 | 7/16-20 UNF | 17mm | 170 | 2,000 |
| AN-6 | 9.53 | 0.3750 | 9/16-18 UNF | 22mm | 380 | 2,000 |
| AN-8 | 12.70 | 0.5000 | 3/4-16 UNF | 27mm | 680 | 2,000 |
| AN-10 | 15.88 | 0.6250 | 7/8-14 UNF | 32mm | 1,060 | 2,000 |
| AN-12 | 19.05 | 0.7500 | 1-1/16-12 UNF | 38mm | 1,520 | 2,000 |
| AN-16 | 25.40 | 1.0000 | 1-5/16-12 UNF | 46mm | 2,700 | 1,500 |
| AN-20 | 31.75 | 1.2500 | 1-5/8-12 UNF | 57mm | 4,200 | 1,200 |
AN Fitting Technical Notes
What does "AN" stand for?
AN stands for Army-Navy — a U.S. military thread standard developed jointly between the US Army and Navy during WWII. The thread form is 37° JIC (Joint Industry Council) flare, which creates a metal-to-metal seal without needing a gasket. The dash number represents the nominal bore ID in 1/16" increments: AN-6 = 6/16" = 3/8" bore.
AN vs JIC vs SAE — Are they the same?
AN and JIC 37° fittings share the same 37° flare seat angle and thread dimensions — they are dimensionally interchangeable for hydraulic connections. SAE 45° flare (common on domestic plumbing) uses a different angle and must never be mixed with AN/JIC without the correct adapter.
Torque specs — how tight is enough?
AN fittings seal on the metal flare, not by torque. The standard method: tighten finger-tight, then use a wrench to turn 1/6 to 1/4 turn further (1–2 flats). Aluminium fittings: typically 5–12 Nm depending on size. Overtightening deforms the flare and causes leaks. Use a backup wrench on the mating fitting.
Sizing for your application
A common rule of thumb: AN-6 for fuel supply up to ~400hp, AN-8 for 400–700hp, AN-10 for 700–1000hp+. Oil drain lines should be one size larger than the supply. Always size for flow velocity — excessively high velocity causes cavitation and pressure drop. Use the Fuel System Sizing calculator for a more precise recommendation.