Dash size decoder
Find AN Fitting Dimensions by Dash Size
Start with the dash number. The page maps it to nominal tube size and common thread identification; the diagram shows what to measure.
Default: -6 AN = 3/8 in nominal tube OD with a common 9/16-18 thread. Change the dash size or display units below.
Identify from measured male thread
Measure the male major diameter across the thread crests and determine TPI with a thread gauge. Diameter alone is not enough.
Nearest listed candidate
Enter both a measured male thread OD and TPI to identify a candidate.
- Selected size
- -6 AN
- Nominal tube OD
- 3/8 in
- Common thread
- 9/16-18
- Male thread Ø
- 0.5625 in
- Pitch
- 1.411 mm
- Seat
- 37°
Identification is not qualification
Matching a dash size, thread, and 37° seat identifies likely geometry only. It does not establish aerospace qualification, working pressure, torque, material compatibility, hose compatibility, or approval for a specific installation.
Reference table
AN Fitting Dash Size and Thread Chart
Common AN dash sizes cross-referenced to nominal tube OD, thread identification, TPI, nominal male thread diameter, metric equivalents, and 37° seat geometry.
Search by dash size, tube fraction, thread designation, TPI, or metric dimension. Use the row action to load a size into the diagram.
No listed AN sizes match these filters. Clear the filter or verify the dash size, thread diameter, TPI, and 37° seat.
Scroll horizontally to view additional columns and vertically to view additional rows. Column headers remain visible while scrolling.
| AN identification | Tube size | Thread identification | Connection | Actions | |||||
|---|---|---|---|---|---|---|---|---|---|
| Seat | Use / 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 | 1.587 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° |
|
Thread designations here are common identification callouts from the approved public cross-reference. Specification-controlled aerospace hardware can impose UNJ/UNJF thread forms, tolerances, materials, inspection, and qualification requirements beyond this lookup.
How AN Dash Sizes Work
For the common rows in this chart, the dash number corresponds to nominal tube outside diameter in sixteenths of an inch. A -6 size is 6/16 in, which reduces to 3/8 in. A -8 size is 8/16 in, or 1/2 in.
The dash number does not equal the male thread diameter. For example, -6 AN relates to 3/8 in nominal tube OD while its common fitting thread identification is 9/16-18.
That distinction matters when identifying an unknown fitting: measure the thread and count TPI, then verify the 37° seat rather than trying to infer the dash size from the hex or a flexible hose’s outside diameter.
Use this only for verified rows that follow the conventional AN dash relationship.
How to Measure an AN Fitting
- Make the system safe. Isolate and depressurize the line before disconnecting a fitting.
- Measure the male major thread diameter. Use calipers across the thread crests; do not measure the hex flats.
- Determine TPI. Use a thread-pitch gauge and match the threads per inch to the chart.
- Confirm the sealing surface. AN-style flare connections use a 37° metal-to-metal sealing geometry. Do not assume a threaded part is AN just because the threads engage.
- Verify the governing product specification. Geometry alone does not establish pressure capability, material compatibility, or aerospace qualification.
Field check: a measured diameter close to 0.750 in with 16 TPI points to the -8 row, but the 37° seat and product documentation still need to agree.
AN Fittings vs JIC 37° Fittings
AN and JIC fittings can share closely related 37° flare geometry and familiar dash/thread relationships, which is why the terms are often mixed in informal use. They should not be treated as qualification synonyms.
| Check | AN / aerospace context | JIC / industrial context |
|---|---|---|
| Sealing concept | 37° flared connection geometry | 37° flared connection geometry |
| Identification | Dash size plus specification-controlled details | Dash/tube size plus JIC thread and seat identification |
| Qualification | May require aerospace thread forms, materials, inspection, procurement, and approval requirements | Governed by the applicable industrial fitting specification and system requirements |
| Safe conclusion | Matching dimensions do not by themselves prove that two parts are approved substitutes. | |
For industrial hydraulic identification, use the JIC Fitting Size Chart rather than treating this page as a universal interchangeability table.
AN Fitting Size vs Hose Size
Aftermarket hose systems commonly use the same dash convention to label nominal hose size—for example, 3/8 in is commonly sold as -6. That does not mean every -6 hose has exactly 3/8 in of measured internal diameter.
Actual hose ID and OD change with liner material, reinforcement, wall thickness, and product family. Parker’s aerospace 112 hose data, for example, pairs dash/tube-size conventions with product-specific nominal hose dimensions rather than claiming one universal actual bore for every hose construction.
Selection rule: choose hose and hose ends from a compatible manufacturer system and use the manufacturer’s pressure, temperature, media, assembly, and qualification data. Do not use this fitting chart as a hose-flow or pressure-rating table.
AN Thread Identification Examples
Example 1: Decode a -6 AN fitting
Known: the fitting is marked -6 and has a verified 37° flare seat.
Nominal tube OD: 6 ÷ 16 = 0.375 in = 3/8 in = 9.53 mm.
Chart lookup: the common thread identification is 9/16-18. Its nominal male thread diameter is 0.5625 in (14.29 mm), and 18 TPI corresponds to a calculated 1.411 mm pitch.
Sanity check: the 0.5625 in thread diameter is larger than the 0.375 in nominal tube OD, confirming that dash size is not thread diameter.
Example 2: Identify a measured fitting
Measured: male thread OD = 0.750 in and thread gauge = 16 TPI.
Lookup: the 16-TPI row with a 0.7500 in nominal male thread diameter is -8 AN, corresponding to 1/2 in nominal tube OD.
Verification: confirm the sealing seat is 37° and check the component specification before treating it as a compatible AN connection.
Common AN Fitting Identification Mistakes
Using dash size as thread diameter
-6 means a 3/8 in nominal tube-size relationship, not a 3/8 in male thread.
Measuring the hex
Wrench-flat dimensions vary by fitting design. Measure the actual thread major diameter across the crests.
Ignoring the flare angle
A thread that screws together can still use the wrong sealing geometry. Verify the 37° seat and do not substitute a 45° flare.
Assuming hose OD equals AN size
Flexible-hose OD and actual bore depend on construction; use the hose manufacturer’s compatibility data.
Calling every 37° fitting aerospace AN
Matching geometry does not establish an aerospace procurement specification, thread class, material, inspection, or approval status.
Selection Limitations and Next Steps
This page is an identification and dimensional-reference tool. It intentionally does not publish pressure ratings, tightening torque, flare acceptance tolerances, material limits, aircraft installation approval, or a universal hose ID because those depend on the governing product and system specification.
- Use the component manufacturer or governing specification for pressure, temperature, material, and torque requirements.
- Verify hose and hose-end compatibility as one approved system.
- For aircraft or other regulated applications, confirm the exact procurement and installation requirements rather than relying on dimensional similarity.
- If the measured diameter and TPI do not land on a listed row, do not invent an intermediate AN size.
Standards, Scope, and Data Method
Scope: common AN dash-size identification rows, 37° flare geometry, limited public cross-reference data, and independently calculated metric conversions.
The table is an independently arranged identification crosswalk. SAE standards are cited for aerospace scope and qualification context; their copyrighted dimensional/tolerance tables and figures are not reproduced. Public manufacturer resources are used only for the limited factual cross-checks described below.
- SAE International — AS4395C, Fitting End, Flared, Tube Connection, Design StandardAerospace 37° flared tube-connection design-standard context; current status checked during page generation.
- SAE International — AS4841B, Fittings, 37° Internal Flare, Fluid Connection, Procurement SpecificationHistorical 2017 revision retained as the handoff-approved scope reference; SAE has published later revisions, so current procurement work must use the revision required by the governing specification.
- Russell Performance Technical ResourcesPublic common AN size, metal tube OD, and thread-size cross-reference for the -3 through -20 rows used here.
- Parker Stratoflex Catalog 106-112 — 112 Hose Products for the Aerospace IndustryCatalog 106-112, March 2000; cross-checks the dash/tube-size convention for common aerospace hose/fitting sizes and documents product-specific selection limits.
Dataset and Source-Check Details
- Dataset
- T2E-AN-CROSSWALK-2026-08-16
- Source checked
- August 16, 2026
- Publisher
- Turn2Engineering
- Source-controlled fields
- Dash size, nominal tube OD, common thread designation, and TPI from the public cross-reference; 37° aerospace connection context from SAE/Parker scope material
- Calculated fields
- Metric tube/thread dimensions and pitch using 25.4 mm/in
- Rights decision
- Limited transformed factual cross-reference; no SAE table/figure reproduction and no full CSV download
- Missing values
- Shown as —; unlisted sizes are not extrapolated
- Maintenance trigger
- Recheck when controlling SAE status/revisions or public cross-reference sources materially change
AN Fitting Size Chart FAQ
A common -6 AN identification is 9/16-18 with a 3/8 in nominal tube-size relationship; verify the 37° seat and governing product specification before assuming compatibility.
No. AN dash size is a nominal sizing convention; actual flexible-hose inside and outside dimensions vary with the specific hose construction and manufacturer.
They can share closely related dash/thread dimensions and 37° flare geometry, but matching dimensions do not make industrial JIC hardware automatically equivalent to specification-controlled aerospace AN hardware.
Measure the male major-thread OD, determine TPI with a thread gauge, confirm the 37° seat, and use the nearest listed row only as an identification candidate.
AN-style flare connections use 37° sealing geometry; a 45° flare should not be substituted merely because a threaded connection appears to engage.
Use the Dash Size, Then Verify the Connection
For a known AN designation, use the chart to translate dash size into nominal tube OD and common thread identification. For an unknown fitting, measure the male thread OD, determine TPI, and confirm the 37° seat. Treat the result as dimensional identification—not as proof of pressure rating, hose compatibility, or aerospace approval.