JIC Dash Size Chart and What Dash Numbers Mean

A JIC dash size is the tube OD in sixteenths of an inch: -8 means 1/2 in tube. This chart pairs every dash size with its tube OD and thread.

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

A JIC dash size is the tube outside diameter in sixteenths of an inch. Divide the dash number by 16 and you have the tube OD: -8 is 8/16 = 1/2 in, -12 is 12/16 = 3/4 in. The dash number does not tell you the thread size directly, so this chart lists both. It covers every size in SAE J514, from -2 to -32.

JIC dash size chart

Tube and thread sizes per SAE J514 as published by Parker and Eaton; every source checked agrees on these rows. Metric values are converted from inch at 25.4 mm/in. Linked dash numbers open a page with the full dimensions and look-alikes for that size. Male and female thread measurements for every size are on the JIC fitting size chart.

What "dash size" means

The dash system is a shorthand that hydraulic catalogs use for size. The number after the dash counts sixteenths of an inch. On a tube fitting such as JIC, it is the outside diameter of the tube the fitting is made for. So a "-6 JIC" is a fitting for 6/16 in (3/8 in) tube, and people often call it a "3/8 JIC" for that reason.

The thread is always larger than the tube, because the nut has to pass over the tube and the flare. A -6 JIC has a 9/16-18 thread, not a 3/8 in thread. Ordering a fitting by measuring the thread and calling it the dash size is the most common sizing mistake (see common JIC fitting mistakes).

How to convert a dash size

• Dash to inches: divide by 16. -10 ÷ 16 = 0.625 in (5/8 in).
• Dash to millimetres: divide by 16, then multiply by 25.4. -10 = 0.625 × 25.4 = 15.88 mm.
• Inches to dash: multiply the tube OD by 16. A 3/4 in tube is 0.75 × 16 = -12.
• Thread to dash: there is no formula. Measure the thread and look it up in the chart above, or use the finder on the JIC identification page.

The gap between tube and thread grows with size. Working from the chart: the JIC thread is 3/16 in larger than the tube OD from -2 to -6 (7/16 vs 1/4 in at -4), 1/4 in larger at -8 and -10, 5/16 in larger at -12 to -16, 3/8 in larger at -20 and -24, and 1/2 in larger at -32. Use the chart rather than memorising the steps.

Sizes that are rare or missing

• -2 and -3 are small instrument and pilot-line sizes. They are listed in SAE J514 but many distributor charts start at -4.
• -5 and -14 exist but are much less common than their neighbours. They are often missing from parts bins, which is why a -5 or -14 fitting is easy to mistake for -4/-6 or -12/-16.
• There is no -7, -9, -11, -13 or -15 JIC in common use. Above -16, the sizes jump to -20, -24 and -32.

The same dash number on other connections

Dash numbers are used for hose, tube and port fittings, but they do not always measure the same thing. On an adapter with two different ends, each end can carry its own dash number. This table shows how a -8 reads on different connections:

ORB, ORFS and SAE 45° threads as listed in the Eaton and Parker identification guides. NPT dash convention as used in adapter part numbers (for example a -8 NPT end is 1/2-14 NPT). Hose bores per SAE J517 as listed by Parker, Gates and others; see JIC hose end sizes for the full hose table and the SAE 100R5 exception.

The practical rule: a dash number tells you which "family" of sizes a part belongs to, but it does not prove two parts fit. A -8 JIC male and a -8 ORFS female both carry -8, but their threads are different. A -8 JIC male and a -8 ORB port share a thread but seal differently. Check the connection type first, then the dash.

Dash sizes and metric tube

Metric tube is sized directly in millimetres (6, 8, 10, 12, 16 mm and so on) and does not use dash numbers. Some sizes are close to inch tube but not the same: 6 mm tube is about 0.35 mm smaller than -4 (6.35 mm), and 10 mm tube is about 0.48 mm larger than -6 (9.53 mm). A JIC sleeve or flare made for one will not seal reliably on the other. The JIC metric conversion chart lists every dash size in millimetres and the metric threads that look like JIC.

How to find the dash size of an unknown fitting

1. Measure the tube OD, if the fitting is still on a tube. Measure away from the flare and multiply by 16.
2. Otherwise, measure the thread. Take the male thread OD with calipers, or the female ID across the inner crests.
3. Count the threads per inch with a thread gauge. The JIC thread pitch chart shows which sizes share a pitch.
4. Check the seat angle. 37° means JIC; 45° means SAE 45° flare, which shares most JIC dash threads.
5. Match the readings to the chart above. Real threads read slightly under nominal, especially when worn.

The full method, including what to do when a reading falls between two sizes, is in how to measure JIC fittings.

SAE J514 lists JIC fitting sizes by these dash numbers; see SAE J514 explained.

References

SAE J514 tube and thread sizes as published by Parker and Eaton; Eaton Thread Identification Guide; McGill Hose thread identification guide; SAE J517 hose dash convention as summarised by Parker, Gates and Hose and Fittings. Values are reference only.

Frequently asked questions

What does the dash number mean on a JIC fitting?

It is the tube outside diameter in sixteenths of an inch. A -8 JIC fitting is for 8/16 in (1/2 in) OD tube.

Is the JIC dash size the thread size?

No. The thread is always larger. A -8 JIC has a 3/4-16 thread and a -12 JIC has a 1-1/16-12 thread.

How do I convert a dash size to millimetres?

Divide the dash number by 16 and multiply by 25.4. For example, -6 is 6/16 × 25.4 = 9.53 mm.

Is there a -7 or -9 JIC fitting?

Not in common use. The JIC sizes in SAE J514 are -2, -3, -4, -5, -6, -8, -10, -12, -14, -16, -20, -24 and -32.

Does a -8 hose take -8 JIC fittings?

Usually. Most hose dash numbers give the inside diameter in sixteenths, and a -8 hose normally has -8 ends. Reducing ends exist, and SAE 100R5 hose is sized differently, so check the end itself.