JIC Fitting Size Chart (SAE J514, 37° Flare)

Dash size, tube OD, thread size, TPI and measured thread diameters for every standard JIC 37° flare size from -2 to -32, in inches and millimetres.

Last updated October 30, 2026. Reference values; verify against manufacturer specifications.

This page is a quick reference for JIC 37° flare hydraulic fittings. The chart covers every standard dash size from -2 to -32, with tube size, thread size, threads per inch (TPI), and the thread diameters you would actually measure with calipers. Below the chart you will find short explanations of how JIC sizing works and a step-by-step method for identifying an unknown fitting.

JIC fitting size chart (-2 to -32)

All values follow SAE J514 (the standard that defines JIC 37° flare connections). Inch values are nominal; millimetre values are converted at exactly 25.4 mm per inch.

How to read the chart:

• Dash size is the tube outside diameter in sixteenths of an inch. A -8 fitting is for 8/16 in (1/2 in) tube.
• Thread is written as major diameter and threads per inch. 3/4-16 means a 3/4 in thread with 16 threads per inch.
• Male thread OD is the nominal outside diameter of the male thread. A worn or real-world thread usually measures slightly under this value.
• Female thread ID is an approximate measurement across the thread crests inside the female nut. Published catalogs differ by about 0.01–0.02 in for some sizes, so treat it as a guide, not a tolerance.
• Sizes -2 through -10 use UNF (fine) threads. Sizes -12 and larger use 12-pitch UN threads.

What is a JIC fitting?

A JIC fitting is a hydraulic connection that seals with a 37° flare. The name comes from the Joint Industry Council (sometimes written Joint Industrial Council), an industry group that is no longer active. The connection is now defined by SAE J514 and, internationally, by ISO 8434-2.

JIC fittings are used on hydraulic hose ends, tube connections, and adapters across agricultural, construction, industrial, and mobile equipment. They are popular because the design is simple, widely available, and can be taken apart and reassembled.

A JIC joint has three working parts: a male end with a 37° cone-shaped nose, a female swivel nut, and either a flared tube or a matching 37° seat on a hose end. When the nut is tightened, the two 37° surfaces are pressed together. The seal is metal-to-metal on the flare. The threads only hold the parts together; they do not seal. That is why JIC fittings are assembled without thread tape or sealant.

What does "37° flare" mean?

The 37° refers to the angle of the sealing cone, measured from the fitting's centerline. The included angle across the whole cone is 74°. On a male JIC fitting you can see this as the smooth, cone-shaped nose in front of the threads. On a female JIC swivel, the matching seat sits inside the nut.

The angle matters because flare fittings only seal when both surfaces have the same angle. A 37° seat pressed against a 45° seat touches on a thin line instead of a full face, and that joint may leak or fail under pressure even if the threads screw together.

How JIC dash sizes work

The dash number is the tube outside diameter in sixteenths of an inch:

• -4 = 4/16 in = 1/4 in tube
• -6 = 6/16 in = 3/8 in tube
• -8 = 8/16 in = 1/2 in tube
• -12 = 12/16 in = 3/4 in tube
• -16 = 16/16 in = 1 in tube

The dash number does not describe the thread diameter. A -6 JIC fitting has a 9/16 in thread even though it is for 3/8 in tube. This is the most common source of confusion when people ask for a "3/8 JIC fitting": they may mean the 3/8 in tube size (-6) or something that measures 3/8 in across the threads (-3).

On hydraulic hose, the dash number usually refers to the hose inside diameter, also in sixteenths of an inch. A -8 hose has a 1/2 in bore. Hose ends are often, but not always, the same dash size as the hose, so always check the end connection on its own.

Why some JIC threads overlap with SAE 45° flare

SAE 45° flare fittings (SAE J512) are an older flare design used for fuel, refrigeration, and lower-pressure lines. In several dash sizes they share exactly the same thread as JIC, so a 37° part and a 45° part can screw together. In other sizes the threads are different, as shown below.

Common charts do not list SAE 45° flare sizes beyond -16. Because the threads match in sizes -2, -3, -4, -5, -8 and -10, the thread alone cannot tell you whether a fitting is 37° or 45°. You need to check the seat angle. See JIC vs SAE 45° flare for a full comparison.

JIC also shares its thread sizes and 37° seat with AN (Army-Navy) fittings used in aerospace and motorsport. AN parts are made to a tighter military specification, but the basic sizes match.

How to identify a JIC fitting

You need a set of calipers, an inch thread pitch gauge (ideally with a metric gauge as well), and a seat angle gauge that includes 37° and 45°. Then work through these steps:

1. Clean the threads and seat. Dirt and paint can throw off a caliper reading by enough to point you to the wrong size.
2. Decide male or female. A male fitting has threads on the outside; a female fitting has threads inside the nut.
3. Look for a seat. JIC male ends have a cone-shaped nose in front of the threads. If the male end has no cone but has an O-ring or an O-ring groove near the hex, it is probably an O-ring boss (ORB) fitting. If the threads get narrower toward the end, it is a tapered pipe thread such as NPT.
4. Measure the thread diameter. On a male fitting, measure across the thread crests (outside diameter). On a female fitting, measure across the inside thread crests. Compare the result with the chart above.
5. Check the threads per inch. Hold the thread gauge against the threads until the teeth sit fully with no light showing. JIC uses 24, 20, 18, 16, 14 or 12 TPI depending on size. If no inch gauge fits but a metric one does, the fitting is not JIC.
6. Check the seat angle. Place the seat gauge against the cone or seat. The correct angle sits flush, with the gauge parallel to the fitting's centerline. A 37° reading confirms JIC (or AN). A 45° reading means SAE 45° flare. A 24° or 30° reading points to metric or Japanese fittings.
7. Match all three. A fitting is JIC only when the thread diameter, TPI and 37° seat all agree with one row of the chart.

For more detail, including what to do when a measurement falls between two sizes, see how to measure JIC fittings.

Most-used JIC sizes at a glance

• -4 JIC: 1/4 in tube, 7/16-20 thread
• -6 JIC: 3/8 in tube, 9/16-18 thread
• -8 JIC: 1/2 in tube, 3/4-16 thread
• -10 JIC: 5/8 in tube, 7/8-14 thread
• -12 JIC: 3/4 in tube, 1-1/16-12 thread
• -16 JIC: 1 in tube, 1-5/16-12 thread

Related guides

• JIC vs ORB: same threads, completely different seals.
• JIC vs SAE 45° flare: how to tell 37° from 45°.
• How to measure JIC fittings: calipers, thread gauges and seat gauges.
• JIC metric conversion chart: every size in millimetres, plus metric and BSP look-alikes.
• Common JIC fitting mistakes: mixed seats, overtightening and FFWR basics.

References

The chart was cross-checked against published thread identification guides from hydraulic manufacturers and distributors, including the Eaton Thread Identification Guide, the McGill Hose thread identification guide, Ryco's JIC 37° flare thread data, and the Maxbar SAE J514 end-fitting chart. Values are for reference only; always confirm against the fitting manufacturer's specifications. See the disclaimer.

Frequently asked questions

What size is a -6 JIC fitting?

A -6 JIC fitting is for 3/8 in (9.53 mm) outside-diameter tube and has a 9/16-18 UNF thread. The male thread measures about 0.56 in (14.29 mm) across the crests.

What does the dash number on a JIC fitting mean?

The dash number is the tube outside diameter in sixteenths of an inch. For example, -8 means 8/16 in, which is 1/2 in tube. It does not describe the thread diameter.

What dash size is a 9/16 JIC thread?

A 9/16-18 thread is a -6 JIC fitting, which is for 3/8 in tube.

Are JIC threads UNF?

Sizes -2 through -10 use UNF threads (24 to 14 TPI). Sizes -12 and larger use 12-pitch UN threads, such as 1-1/16-12 for -12.

Is JIC the same as SAE 45° flare?

No. JIC uses a 37° seat and SAE 45° flare uses a 45° seat. The threads are identical in some sizes (-2, -3, -4, -5, -8, -10), so the parts can screw together, but the seats do not seal properly against each other.

Are JIC and AN fittings the same?

They share the same 37° flare angle and thread sizes, so they generally connect. AN fittings are made to a military specification with a tighter thread class and different material requirements, so they are not identical parts.

Do JIC fittings need thread sealant or PTFE tape?

No. JIC fittings seal metal-to-metal on the 37° flare, not on the threads. Tape or sealant on the threads does not help the seal and can contaminate the hydraulic system.

Can a JIC fitting go into an ORB port?

A male JIC fitting can thread into an ORB port of the same dash size because the threads match, but it will not seal: an ORB port needs an O-ring fitting. Use a proper JIC-to-ORB adapter instead.