Measure, then match
Hydraulic thread identifier
Enter the thread diameter and pitch you measured. The tool lists the JIC, ORFS, BSP, NPT, metric DIN, Komatsu, and SAE 45° sizes that fit, and tells you which sealing surface confirms each one.
Enter your measurements
Use calipers for the diameter and a thread pitch gauge for the pitch. Pitch is optional but makes the result much narrower.
Matching threads
Several fitting families share the same thread. Always check the sealing surface and seat angle, and test with a known mating fitting before ordering.
Worn and damaged threads measure small
Clean the thread before measuring and measure across undamaged crests. Never force two fittings together to test a match: threads that start but bind after a turn or two are a different standard.
How to identify a hydraulic thread
Four checks that identify a hydraulic connection
- Parallel or tapered: lay a straight edge or caliper jaw along the thread. If the diameter is the same along the thread it is parallel; if it grows toward the hex it is tapered.
- Diameter: measure the outside diameter of a male thread across the crests, or the inside diameter of a female thread. On a tapered thread, measure at the fourth or fifth full thread.
- Pitch: use a thread pitch gauge. Imperial gauges read threads per inch (TPI); metric gauges read the distance between crests in millimetres.
- Seal: look at how the joint seals — a 37° cone, a 24° or 30° cone, a flat face with an O-ring, an O-ring at the base of the thread, or the tapered thread itself.
Diameter and pitch identify the thread. The sealing surface identifies the fitting family. Several families share threads, so both are needed.
How the identifier matches a measurement
The tool compares your diameter with the nominal thread diameter of every size in the tables below. Male threads measure slightly under nominal. A female bore is smaller than nominal by roughly one pitch, so the tool estimates it from the thread form.
If you enter a pitch, only sizes within 3% of it are kept. A match is marked "Strong match" when the pitch agrees and the diameter is within about 0.35 mm for a male thread. Otherwise it is "Possible match" and must be confirmed with the seal check.
Threads that are easily confused
1/2 in NPT and 1/2 in BSP both have 14 threads per inch and differ by only 0.4 mm in diameter. NPT has a 60° thread angle; BSP has 55°. Check with a pitch gauge of the correct form and look at the seal.
JIC 37° and SAE 45° flare share the same thread in -04, -05, -08 and -10. Only the seat angle tells them apart.
Metric M-threads are shared by DIN 24° light series, DIN 24° heavy series and Komatsu 30° flare. The cone angle and the tube counterbore decide which one it is.
BSPP (G) with a 60° cone and JIS 30° flare both use G threads. Check the seat angle.
JIC 37° flare thread chart
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| -02 | 5/16-24 | 7.94 mm / 0.313 in | 24 TPI |
| -03 | 3/8-24 | 9.53 mm / 0.375 in | 24 TPI |
| -04 | 7/16-20 | 11.11 mm / 0.438 in | 20 TPI |
| -05 | 1/2-20 | 12.70 mm / 0.500 in | 20 TPI |
| -06 | 9/16-18 | 14.29 mm / 0.563 in | 18 TPI |
| -08 | 3/4-16 | 19.05 mm / 0.750 in | 16 TPI |
| -10 | 7/8-14 | 22.23 mm / 0.875 in | 14 TPI |
| -12 | 1-1/16-12 | 26.99 mm / 1.063 in | 12 TPI |
| -14 | 1-3/16-12 | 30.16 mm / 1.188 in | 12 TPI |
| -16 | 1-5/16-12 | 33.34 mm / 1.313 in | 12 TPI |
| -20 | 1-5/8-12 | 41.28 mm / 1.625 in | 12 TPI |
| -24 | 1-7/8-12 | 47.63 mm / 1.875 in | 12 TPI |
| -32 | 2-1/2-12 | 63.50 mm / 2.500 in | 12 TPI |
Seal: 37° cone seat, metal to metal. Look for a 37° flared cone on the male nose (74° included angle). The thread is parallel. SAE O-ring boss ports (SAE J1926) use the same UN threads but seal with an O-ring at the base of the male thread instead of a flare.
ORFS (O-ring face seal) thread chart
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| -04 | 9/16-18 | 14.29 mm / 0.563 in | 18 TPI |
| -06 | 11/16-16 | 17.46 mm / 0.688 in | 16 TPI |
| -08 | 13/16-16 | 20.64 mm / 0.813 in | 16 TPI |
| -10 | 1-14 | 25.40 mm / 1.000 in | 14 TPI |
| -12 | 1-3/16-12 | 30.16 mm / 1.188 in | 12 TPI |
| -16 | 1-7/16-12 | 36.51 mm / 1.438 in | 12 TPI |
| -20 | 1-11/16-12 | 42.86 mm / 1.688 in | 12 TPI |
| -24 | 2-12 | 50.80 mm / 2.000 in | 12 TPI |
Seal: Flat face with an O-ring in a groove on the male end. The male end is flat with an O-ring groove in the face. The thread is parallel.
BSPP (G) parallel thread chart
BSPT (R) tapered threads use the same diameters and pitches as the G sizes below.
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| 1/8 in | G 1/8 | 9.73 mm / 0.383 in | 28 TPI |
| 1/4 in | G 1/4 | 13.16 mm / 0.518 in | 19 TPI |
| 3/8 in | G 3/8 | 16.66 mm / 0.656 in | 19 TPI |
| 1/2 in | G 1/2 | 20.96 mm / 0.825 in | 14 TPI |
| 5/8 in | G 5/8 | 22.91 mm / 0.902 in | 14 TPI |
| 3/4 in | G 3/4 | 26.44 mm / 1.041 in | 14 TPI |
| 1 in | G 1 | 33.25 mm / 1.309 in | 11 TPI |
| 1-1/4 in | G 1-1/4 | 41.91 mm / 1.650 in | 11 TPI |
| 1-1/2 in | G 1-1/2 | 47.80 mm / 1.882 in | 11 TPI |
| 2 in | G 2 | 59.61 mm / 2.347 in | 11 TPI |
Seal: 60° cone in the male nose, or a bonded washer / O-ring on the shoulder. The thread is parallel with a 55° Whitworth form. Hose fittings usually have a 60° internal cone in the male. A 30° flare seat on a G thread indicates JIS 30° flare (JIS B 8363) instead.
NPT tapered pipe thread chart
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| 1/8 in | 1/8-27 NPT | 10.29 mm / 0.405 in | 27 TPI |
| 1/4 in | 1/4-18 NPT | 13.72 mm / 0.540 in | 18 TPI |
| 3/8 in | 3/8-18 NPT | 17.15 mm / 0.675 in | 18 TPI |
| 1/2 in | 1/2-14 NPT | 21.34 mm / 0.840 in | 14 TPI |
| 3/4 in | 3/4-14 NPT | 26.67 mm / 1.050 in | 14 TPI |
| 1 in | 1-11.5 NPT | 33.40 mm / 1.315 in | 11.5 TPI |
| 1-1/4 in | 1-1/4-11.5 NPT | 42.16 mm / 1.660 in | 11.5 TPI |
| 1-1/2 in | 1-1/2-11.5 NPT | 48.26 mm / 1.900 in | 11.5 TPI |
| 2 in | 2-11.5 NPT | 60.33 mm / 2.375 in | 11.5 TPI |
Seal: Seals on the tapered thread flanks; NPT needs sealant. The thread is tapered and has a 60° thread angle. The diameter grows along the thread.
Metric DIN 24° light series (L) thread chart
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| 6L (tube OD 6 mm) | M12x1.5 | 12.00 mm / 0.472 in | 1.5 mm |
| 8L (tube OD 8 mm) | M14x1.5 | 14.00 mm / 0.551 in | 1.5 mm |
| 10L (tube OD 10 mm) | M16x1.5 | 16.00 mm / 0.630 in | 1.5 mm |
| 12L (tube OD 12 mm) | M18x1.5 | 18.00 mm / 0.709 in | 1.5 mm |
| 15L (tube OD 15 mm) | M22x1.5 | 22.00 mm / 0.866 in | 1.5 mm |
| 18L (tube OD 18 mm) | M26x1.5 | 26.00 mm / 1.024 in | 1.5 mm |
| 22L (tube OD 22 mm) | M30x2 | 30.00 mm / 1.181 in | 2 mm |
| 28L (tube OD 28 mm) | M36x2 | 36.00 mm / 1.417 in | 2 mm |
| 35L (tube OD 35 mm) | M45x2 | 45.00 mm / 1.772 in | 2 mm |
| 42L (tube OD 42 mm) | M52x2 | 52.00 mm / 2.047 in | 2 mm |
Seal: 24° internal cone, with a cutting ring or an O-ring cone (DKOL). The male has a 24° internal cone and a counterbore that fits the tube OD shown.
Metric DIN 24° heavy series (S) thread chart
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| 6S (tube OD 6 mm) | M14x1.5 | 14.00 mm / 0.551 in | 1.5 mm |
| 8S (tube OD 8 mm) | M16x1.5 | 16.00 mm / 0.630 in | 1.5 mm |
| 10S (tube OD 10 mm) | M18x1.5 | 18.00 mm / 0.709 in | 1.5 mm |
| 12S (tube OD 12 mm) | M20x1.5 | 20.00 mm / 0.787 in | 1.5 mm |
| 14S (tube OD 14 mm) | M22x1.5 | 22.00 mm / 0.866 in | 1.5 mm |
| 16S (tube OD 16 mm) | M24x1.5 | 24.00 mm / 0.945 in | 1.5 mm |
| 20S (tube OD 20 mm) | M30x2 | 30.00 mm / 1.181 in | 2 mm |
| 25S (tube OD 25 mm) | M36x2 | 36.00 mm / 1.417 in | 2 mm |
| 30S (tube OD 30 mm) | M42x2 | 42.00 mm / 1.654 in | 2 mm |
| 38S (tube OD 38 mm) | M52x2 | 52.00 mm / 2.047 in | 2 mm |
Seal: 24° internal cone, with a cutting ring or an O-ring cone (DKOS). The male has a 24° internal cone and a counterbore that fits the tube OD shown. Heavy series has a thicker wall than light series.
Komatsu 30° flare thread chart
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| M14 | M14x1.5 | 14.00 mm / 0.551 in | 1.5 mm |
| M18 | M18x1.5 | 18.00 mm / 0.709 in | 1.5 mm |
| M22 | M22x1.5 | 22.00 mm / 0.866 in | 1.5 mm |
| M24 | M24x1.5 | 24.00 mm / 0.945 in | 1.5 mm |
| M30 | M30x1.5 | 30.00 mm / 1.181 in | 1.5 mm |
| M33 | M33x1.5 | 33.00 mm / 1.299 in | 1.5 mm |
| M36 | M36x1.5 | 36.00 mm / 1.417 in | 1.5 mm |
| M42 | M42x1.5 | 42.00 mm / 1.654 in | 1.5 mm |
Seal: 30° cone seat, metal to metal. Metric fine thread with a 30° flare seat. Found mainly on Komatsu machines; check the seat angle before matching to DIN.
SAE 45° flare thread chart
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| -04 | 7/16-20 | 11.11 mm / 0.438 in | 20 TPI |
| -05 | 1/2-20 | 12.70 mm / 0.500 in | 20 TPI |
| -06 | 5/8-18 | 15.88 mm / 0.625 in | 18 TPI |
| -08 | 3/4-16 | 19.05 mm / 0.750 in | 16 TPI |
| -10 | 7/8-14 | 22.23 mm / 0.875 in | 14 TPI |
| -12 | 1-1/16-14 | 26.99 mm / 1.063 in | 14 TPI |
Seal: 45° cone seat, metal to metal. The cone is 45°, steeper than JIC. Check with a seat-angle gauge; several sizes share a thread with JIC but must not be mixed.
Frequently asked questions
How do I tell JIC from BSP?
JIC has a 37° external cone on the male and UN threads counted in threads per inch, such as 3/4-16. BSPP has a 55° thread form, different diameters, and usually a 60° internal cone in the male. Measure diameter and pitch: a 3/4-16 JIC male measures about 19.0 mm, while G 1/2 measures about 20.9 mm with 14 TPI.
How do I tell NPT from BSPT?
Both are tapered. NPT has a 60° thread angle and BSPT has 55°. Their pitches differ in most sizes: 1/4 in is 18 TPI in NPT and 19 TPI in BSPT; 1 in is 11.5 TPI in NPT and 11 TPI in BSPT. In 1/2 in and 3/4 in both are 14 TPI, so compare the diameter and use the correct thread gauge.
What thread is a -08 JIC fitting?
A -08 JIC 37° fitting has a 3/4-16 UN thread. The male thread outside diameter is about 19.05 mm (0.75 in).
What thread is a -08 ORFS fitting?
A -08 ORFS fitting has a 13/16-16 UN thread. The male thread outside diameter is about 20.6 mm (0.81 in).
Can I identify a thread without a pitch gauge?
You can narrow it down by diameter alone, and the tool will list every size that fits. The result is then only a possible match. Count the threads over one inch or measure across ten crests to estimate the pitch.
Why does my female thread measure smaller than the chart?
The chart gives the male outside diameter. The bore of a female thread is smaller by about one thread pitch. Select "Female thread (inside diameter)" and the tool adjusts for this.
Are metric threads on Komatsu machines the same as DIN?
They use the same metric fine threads, such as M18×1.5, but Komatsu fittings seal on a 30° flare while DIN fittings seal on a 24° cone. They are not interchangeable.
Related tools and guides
Standards and sources
- SAE J514 / ISO 8434-2 — 37° flare fittings.
- SAE J1453 / ISO 8434-3 — O-ring face seal fittings.
- ISO 228-1 (G parallel) and ISO 7-1 (R tapered) — pipe threads with 55° form.
- ASME B1.20.1 — NPT pipe threads.
- ISO 8434-1 / DIN 2353 — 24° cone fittings, light and heavy series.
- SAE J512 — 45° flare fittings.
Reference values are nominal. The manufacturer specification for the exact hose and fitting takes precedence.