Quick reference · 9 verified rows
AN Fitting Thread Size Chart
Example: -6 AN = 3/8 in tube OD · 9/16-18 thread · 18 TPI · 37° flare.
| AN size | Tube OD | Thread size | TPI | Male thread OD |
|---|---|---|---|---|
| -3 AN | 3/16 in4.76 mm | 3/8-24 | 24TPI | 0.3750 in9.53 mm |
| -4 AN | 1/4 in6.35 mm | 7/16-20 | 20TPI | 0.4375 in11.11 mm |
| -5 AN | 5/16 in7.94 mm | 1/2-20 | 20TPI | 0.5000 in12.70 mm |
| -6 AN | 3/8 in9.53 mm | 9/16-18 | 18TPI | 0.5625 in14.29 mm |
| -8 AN | 1/2 in12.70 mm | 3/4-16 | 16TPI | 0.7500 in19.05 mm |
| -10 AN | 5/8 in15.88 mm | 7/8-14 | 14TPI | 0.8750 in22.23 mm |
| -12 AN | 3/4 in19.05 mm | 1-1/16-12 | 12TPI | 1.0625 in26.99 mm |
| -16 AN | 1 in25.40 mm | 1-5/16-12 | 12TPI | 1.3125 in33.34 mm |
| -20 AN | 1-1/4 in31.75 mm | 1-5/8-12 | 12TPI | 1.6250 in41.28 mm |
No listed sizes match that search. Try a dash size (such as -6), tube size or thread designation.
Tube OD is the nominal size convention, not the actual male thread diameter or a guaranteed hose bore. Male thread OD is nominal; actual manufactured threads have tolerances. See all metric dimensions and thread pitch ↓
Selected size
-6 AN fitting
- Nominal tube OD
- 3/8 in 9.53 mm
- Common thread
- 9/16-18 18 TPI
- Male thread OD
- 0.5625 in 14.29 mm
- Thread pitch
- 1.411 mm 37° flare seat
Click any size in the chart to update these dimensions. Verify the 37° seat and manufacturer specification before installation.
No AN marking?
Identify an AN Fitting by Thread Diameter
Measure the male outside-thread diameter across the thread crests with calipers, then check the threads per inch (TPI) with a thread gauge. The tool compares your values to the nine sizes above.
Example: 0.750 in (19.05 mm) and 16 TPI points to -8 AN. Diameter without a matching TPI is not enough.
Safety: Depressurize the system before disconnecting it. A dimensional match identifies a candidate—not pressure rating, interchangeability, aerospace approval or safe working torque.
Reference data · inches and millimeters
Complete AN Fitting Dimensions Table
This extended cross-reference includes nominal thread major diameter, metric equivalents and calculated thread pitch. Horizontally scroll the table on smaller screens.
| AN dash | Tube OD (in) | Tube OD (mm) | Common thread | TPI | Male thread OD (in) | Male thread OD (mm) | Pitch (mm) | Seat | Copy |
|---|---|---|---|---|---|---|---|---|---|
| -3 AN | 3/16 in | 4.76 mm | 3/8-24 | 24 | 0.3750 in | 9.53 mm | 1.058 mm | 37° | |
| -4 AN | 1/4 in | 6.35 mm | 7/16-20 | 20 | 0.4375 in | 11.11 mm | 1.270 mm | 37° | |
| -5 AN | 5/16 in | 7.94 mm | 1/2-20 | 20 | 0.5000 in | 12.70 mm | 1.270 mm | 37° | |
| -6 AN | 3/8 in | 9.53 mm | 9/16-18 | 18 | 0.5625 in | 14.29 mm | 1.411 mm | 37° | |
| -8 AN | 1/2 in | 12.70 mm | 3/4-16 | 16 | 0.7500 in | 19.05 mm | 1.588 mm | 37° | |
| -10 AN | 5/8 in | 15.88 mm | 7/8-14 | 14 | 0.8750 in | 22.23 mm | 1.814 mm | 37° | |
| -12 AN | 3/4 in | 19.05 mm | 1-1/16-12 | 12 | 1.0625 in | 26.99 mm | 2.117 mm | 37° | |
| -16 AN | 1 in | 25.40 mm | 1-5/16-12 | 12 | 1.3125 in | 33.34 mm | 2.117 mm | 37° | |
| -20 AN | 1-1/4 in | 31.75 mm | 1-5/8-12 | 12 | 1.6250 in | 41.28 mm | 2.117 mm | 37° |
Metric conversions: 1 inch = 25.4 mm; pitch in mm = 25.4 ÷ TPI. This table contains the nine common AN rows checked against Russell Performance’s public identification chart; it does not interpolate unlisted sizes.
What to Measure on a 37° Flare Fitting
Measure the external male threads, not the wrench hex or hose outside diameter. The drawing shows identification locations only; it is not to scale and must not be used for manufacturing.
How Do AN Fitting Dash Sizes Work?
For this chart’s conventional sizes, the AN dash number represents nominal tube outside diameter in sixteenths of an inch. AN -6 means 6/16 in = 3/8 in, while AN -8 means 8/16 in = 1/2 in. These nominal tube dimensions are not the outside diameter of the connecting thread.
For instance, an AN -6 fitting uses a common 9/16-18 thread: the 9/16-inch value describes nominal male thread diameter and 18 means 18 threads per inch. The 37° flare is the sealing interface; the straight threads provide clamping force.
How to Identify an AN Fitting Correctly
- Make the line safe. Isolate, depressurize and follow the system’s safety procedure.
- Check for a stamped dash number or part number. Use reliable manufacturer documentation when available.
- Measure across the external thread crests. Use calipers; do not use the hex-flat width as a size identifier.
- Check TPI with a pitch gauge. Compare thread OD and TPI together against the table or identifier above.
- Confirm the 37° mating seat. A connection that threads together may still have an incompatible sealing geometry.
- Verify the product specification. Thread identification does not establish pressure, material, temperature, torque or aerospace approval.
AN vs JIC Fittings: Are They Interchangeable?
AN-style and industrial JIC connections commonly share a 37° flare and the same familiar dash-to-thread relationships. That dimensional similarity does not mean two fittings are automatically approved substitutes.
AN / aerospace
Specify the applicable aerospace part number, approved material, thread form, inspection and procurement controls when the system requires them.
JIC / industrial
Industrial 37° flare connections are governed by their applicable industrial standards and manufacturer requirements. Similar dimensions do not establish aerospace qualification.
For industrial hydraulic fittings, use the JIC Fitting Size Chart. Never substitute 37° and 45° sealing surfaces on thread engagement alone.
Does AN Fitting Size Equal Hose Inside Diameter?
No—not necessarily. In common automotive sizing, -6 is associated with a nominal 3/8-inch hose size; the real flexible-hose inside diameter depends on liner, reinforcement and manufacturer. Russell’s published ProFlex examples show that an AN-labeled hose can have a different actual bore than its nominal dash dimension.
Match hose and hose ends using the manufacturer’s assembly specification. Do not derive flow capacity, working pressure or torque from this chart alone. For hose dimensions, consult the Hydraulic Hose Size Chart and product-specific data.
AN Fitting Size Chart FAQ
What thread size is -6 AN?
A commonly listed -6 AN fitting thread is 9/16-18. Its nominal tube OD is 3/8 in (9.53 mm), with a nominal male thread OD of 0.5625 in (14.29 mm). Confirm its 37° flare seat and specification.
What thread size is -8 AN?
A common -8 AN fitting is 3/4-16, corresponding to 1/2 in nominal tube OD and 0.7500 in nominal male thread OD.
Is AN -10 a 5/8-inch fitting?
-10 AN refers to 5/8 in nominal tube OD. The common external fitting thread is 7/8-14, not 5/8-inch thread.
How do I measure an unmarked AN fitting?
Measure the male thread OD across the thread crests, check TPI using a pitch gauge, and verify a 37° mating seat. The measurement finder above reports dimensional candidates only.
Do AN and JIC fittings have the same threads?
Matching nominal dash sizes often share the same thread designation and 37° flare geometry, but industrial JIC and specification-controlled aerospace AN fittings are not automatically approved substitutes.
Can I connect a 45° flare fitting to 37° AN?
No. Similar-looking threads can engage even when flare seats are incompatible. Verify sealing geometry and manufacturer approval rather than relying on thread engagement.
Engineering References and Data Scope
These are commonly published dimensional identification values, not manufacturing tolerances. This page does not reproduce protected SAE specification tables or certify compatibility.
- Russell Performance — Technical ResourcesPublic AN dash, nominal metal tube OD and fitting-thread cross-reference; source for the nine rows.
- SAE AS4395C — Fitting End, Flared, Tube ConnectionAerospace fitting-end design reference; SAE lists the June 2025 edition as stabilized.
- SAE AS4841D — 37° Internal Flare Fitting ProcurementSAE aerospace procurement context, April 2021 edition; not an interchangeability approval or reproduction of protected dimensional tables.
- SAE J514-1 (2026) — 37° Flared FittingsIndustrial JIC-style 37° flare context; not an aerospace qualification substitute.
Data method: Tube OD and nominal male thread OD are converted from inches using 25.4 mm/in. Pitch is calculated as 25.4/TPI. Source geometry and status checked October 2026. Always follow the governing product drawing and edition required for your application.