-8 JIC Fitting Size and Dimensions
A -8 JIC fitting is for 1/2 in tube and has a 3/4-16 UNF thread. Here are its measurements, look-alikes and tightening values.
Last updated October 30, 2026. Reference values; verify against manufacturer specifications.
The -8 JIC is a workhorse size for main pressure and return lines on mobile and industrial machines. Its 3/4-16 thread is shared with -8 SAE 45° and -8 ORB fittings, and several ORFS, BSP and metric threads come within a millimetre or two. This page gives the full -8 dimensions, the look-alikes and the published tightening values.
-8 JIC at a glance
- Tube size: 1/2 in OD (12.70 mm). The dash number is the tube OD in sixteenths of an inch: 8/16 in = 1/2 in.
- Thread: 3/4-16 UNF: 0.7500 in major diameter, 16 threads per inch.
- Male OD: about 0.75 in (19.05 mm). Female ID: about 0.69 in (17.5 mm).
- Seat: 37° flare, metal-to-metal.
-8 JIC fitting dimensions
| Dimension | Inch | Metric |
|---|---|---|
| Tube OD | 1/2 in (0.500 in) | 12.70 mm |
| Thread | 3/4-16 UNF | pitch 1.588 mm |
| Threads per inch | 16 | 1.588 mm per thread |
| Male thread OD | 0.7500 in | 19.05 mm |
| Female thread ID (approx.) | 0.69 in | 17.5 mm |
| Seat angle | 37° from centreline (74° included) | same |
| Hex size | Varies by maker and part | check the catalog |
Thread and tube sizes per SAE J514 as published by Parker and Eaton. Female ID is the approximate value in the Eaton and McGill identification guides. Metric values are converted from inch at 25.4 mm/in. Hex sizes are not standardised across makers, so they are not listed.
"-8" refers to 1/2 in tube (8/16 in). The thread itself is 3/4 in across, so a fitting sold as "1/2 in JIC" will measure about 0.75 in on the male thread.
How to confirm a -8 JIC fitting
- Check the seat. A male -8 JIC has a convex cone nose. If you have a seat gauge, it should sit flush at 37°.
- Measure the thread. A male should read close to 0.75 in (19.1 mm). A female should read about 0.69 in (17.5 mm) across the inner crests. See how to measure JIC fittings.
- Check the pitch. The 16 TPI leaf of an inch thread gauge should sit flush. The pitch is 1.59 mm, which is not a standard metric pitch, so every leaf of a metric gauge will rock.
- Rule out look-alikes using the table below, or enter your numbers in the finder on the JIC identification page.
Fittings that look like -8 JIC
Three fittings share the exact 3/4-16 thread. A male of any of them threads into a female of the others, so the seat is the test. Others come close:
| Fitting | Thread | OD (in / mm) | TPI or pitch | How to tell |
|---|---|---|---|---|
| -8 SAE 45° flare (SAE J512) | 3/4-16 (same) | 0.75 / 19.05 | 16 TPI | 45° cone instead of 37° |
| -8 ORB (SAE J1926) | 3/4-16 (same) | 0.75 / 19.05 | 16 TPI | O-ring under the hex, no cone |
| -6 ORFS | 11/16-16 | 0.69 / 17.46 | 16 TPI | Flat face; about 1.6 mm smaller |
| -8 ORFS | 13/16-16 | 0.82 / 20.64 | 16 TPI | Flat face; about 1.6 mm larger |
| M18x1.5 metric | M18x1.5 | 0.71 / 18.0 | 1.5 mm (about 16.9 TPI) | Pitch is close; usually a 24° or 30° seat |
| G1/2 BSP | G1/2-14 | 0.82 / 20.96 | 14 TPI | 55° thread, 14 TPI |
| 3/8 NPT | 3/8-18 NPT | about 0.68 / 17.3 | 18 TPI | Tapered thread, no seat |
Look-alike threads from the Eaton and McGill thread identification guides, which agree on these sizes; metric threads are nominal.
The -8 SAE 45° is the classic mix-up. The thread is identical, and the cones differ by only 8°. A 37° and a 45° part will thread together but touch only on a narrow ring, which leaks or damages the seat. See JIC vs SAE 45°. M18x1.5 is close in both diameter and pitch, so a 16 TPI leaf may seem to fit at first glance. Check it over a full inch of thread. Other comparisons: JIC vs ORB, JIC vs ORFS, JIC vs BSP.
Torque and flats for -8 JIC
Parker recommends tightening steel JIC fittings by flats from wrench resistance (FFWR) and gives torque as a reference. Published torque ranges for the same size differ between sources:
| Source | Value | Notes |
|---|---|---|
| Parker Catalog 4400, swivel nut | 1-1/2 flats; reference 42 ft-lb (57 N·m) | FFWR is the recommended method |
| Tameson JIC assembly guide, flared tube nut / swivel nut | 2 flats / 1-1/2 flats | Tube nuts take more rotation than swivels |
| Hose and Fittings assembly chart, tube / swivel | 1-1/2 flats / 1 flat; 43–47 ft-lb | A lower flats count from a second chart |
| SAE J514 range (as published by distributors) | 36–39 ft-lb (49–53 N·m) | Torque range, steel |
Bring the nut to finger-tight, then wrench-tight until you feel resistance. Mark the nut and the fitting, and turn the nut the stated number of flats; one flat is 60°. The full table, with material adjustments, is on the JIC torque chart.
-8 JIC next to its neighbouring sizes
The sizes either side of -8 are -6 and -10. A -8 is about 4.8 mm larger in thread diameter than a -6 and about 3.2 mm smaller than a -10, so these are rarely confused with each other. The look-alikes above are the real risk.
| Dash | Tube OD (in) | Thread | Male OD (mm) | Female ID (mm, approx.) |
|---|---|---|---|---|
| -6 | 3/8 | 9/16-18 | 14.29 | 13.0 |
| -8 | 1/2 | 3/4-16 | 19.05 | 17.5 |
| -10 | 5/8 | 7/8-14 | 22.23 | 20.6 |
Hose, tube and adapters
On hydraulic hose, a -8 dash number normally means a 1/2 in inside diameter. A -8 hose usually has -8 JIC ends, but reducing ends exist, so measure the end. To connect a -8 JIC hose to a port of another type, use an adapter with a male -8 JIC end and the matching port end, such as -8 ORB, 1/2 NPT or G1/2 BSPP. For metric conversions, see the JIC metric conversion chart, and for every size, the JIC fitting size chart.
Other single-size pages: -4 JIC fitting size, -6 JIC fitting size, -10 JIC fitting size, -12 JIC fitting size, -16 JIC fitting size. All sizes in one table: the JIC dash size chart. To check which half of a joint you are holding, see male vs female JIC fittings.
References
SAE J514 dimensions as published by Parker and Eaton; Eaton Thread Identification Guide; McGill Hose thread identification guide; Parker Catalog 4400 assembly methods. Values are reference only.
Frequently asked questions
What thread is a -8 JIC fitting?
3/4-16 UNF: 3/4 in (19.05 mm) major diameter with 16 threads per inch.
What tube size is -8 JIC?
1/2 in OD tube (12.70 mm). The dash number is the tube OD in sixteenths of an inch.
Is -8 JIC the same as 1/2 JIC?
Yes. "1/2 JIC" refers to the tube size. The thread is 3/4-16.
Will a -8 JIC fit a -8 SAE 45° fitting?
They thread together because the thread is the same, but the 37° and 45° seats do not seal against each other. Use matching seats.
How much torque does a -8 JIC need?
Parker gives 1-1/2 flats from wrench resistance for a steel swivel, with a reference torque of 42 ft-lb (57 N·m). Published SAE J514 ranges list 36–39 ft-lb. Follow your fitting maker's instructions.