JIC vs BSP Fittings: Threads, Seats and Look-Alike Sizes
BSP uses 55° Whitworth threads; JIC uses 60° inch threads and a 37° cone. Here is how to tell them apart, with the BSP sizes that come closest to JIC.
Last updated October 30, 2026. Reference values; verify against manufacturer specifications.
BSP (British Standard Pipe) fittings are common on equipment made in the UK, Europe, Asia and Australia. JIC fittings are the norm on North American hydraulics. When a machine or pump from one region meets hoses from another, the two get confused, especially in sizes where the diameters are almost the same. This page shows how to tell them apart and gives the BSP sizes with their nearest JIC look-alikes.
The short answer
- Thread form: JIC threads have a 60° flank angle. BSP threads use the 55° Whitworth form.
- Seal: JIC seals on a 37° cone. BSPP hose ends usually seal on a 60° cone, and BSPP ports seal with a bonded washer or O-ring. BSPT seals on the tapered thread itself.
- Interchange: none. Some sizes are within a fraction of a millimetre, but the pitch or thread angle is different, so do not force them together.
JIC vs BSPP vs BSPT
| Feature | JIC 37° | BSPP (G, parallel) | BSPT (R, tapered) |
|---|---|---|---|
| Thread angle | 60° | 55° Whitworth | 55° Whitworth |
| Thread shape | Parallel | Parallel | Tapered 1:16 |
| Seal | 37° metal cone | 60° cone on hose ends, or a bonded/O-ring seal at a port | Thread interference, with sealant |
| Sizes named by | Dash size (tube OD in 1/16 in) | Nominal pipe size | Nominal pipe size |
| Standard | SAE J514 / ISO 8434-2 | ISO 228-1 (threads) | ISO 7-1 (threads) |
| Common in | North America | UK, Europe, Asia, Australia | UK, Europe, Asia, Australia |
BSPP and BSPT: parallel vs tapered
BSP comes in two forms that share the same sizes and pitches. BSPP (marked G, to ISO 228-1) is parallel. It does not seal on the threads. Instead, a hose end seals on a 60° cone, or a port seals with a bonded washer or O-ring. BSPT (marked R for male and Rc for female, to ISO 7-1) tapers so that the threads seal, much like NPT. A BSPT male gets smaller toward the end. Measure the first few threads and the last few threads: if the diameter changes, it is tapered.
BSPT and NPT are both tapered pipe threads, but the thread angles (55° vs 60°) differ and most pitches differ, so they do not mix either. The JIC vs NPT page covers NPT sizes.
BSP size chart
Like NPT, BSP sizes are nominal. A "1/2 BSP" thread measures about 0.82 in (20.96 mm) across, not 1/2 in. Use the measured diameter and TPI to identify the size.
| BSP size | TPI | Pitch (mm) | Male OD (in) | Male OD (mm, ISO 228-1) | Female ID (in, approx.) |
|---|---|---|---|---|---|
| 1/8 | 28 | 0.91 | 0.38 | 9.73 | 0.35 |
| 1/4 | 19 | 1.34 | 0.52 | 13.16 | 0.47 |
| 3/8 | 19 | 1.34 | 0.65 | 16.66 | 0.60 |
| 1/2 | 14 | 1.81 | 0.82 | 20.96 | 0.75 |
| 5/8 | 14 | 1.81 | 0.88 | 22.91 | 0.80 |
| 3/4 | 14 | 1.81 | 1.04 | 26.44 | 0.97 |
| 1 | 11 | 2.31 | 1.30 | 33.25 | 1.22 |
| 1-1/4 | 11 | 2.31 | 1.65 | 41.91 | 1.56 |
| 1-1/2 | 11 | 2.31 | 1.88 | 47.80 | 1.79 |
| 2 | 11 | 2.31 | 2.35 | 59.61 | 2.26 |
Male and female inch measurements from the Eaton and McGill thread identification guides; mm major diameters from ISO 228-1 tables reproduced in both. Pitch is calculated as 25.4 ÷ TPI.
BSP sizes that look like JIC
| BSP thread | BSP OD / TPI | JIC size | JIC OD / TPI | What tells them apart |
|---|---|---|---|---|
| G1/4 | 13.16 mm (0.518 in) / 19 | -5 (1/2-20) | 12.70 mm (0.500 in) / 20 | Pitch is close; check the thread angle (55° vs 60°) |
| G1/2 | 20.96 mm / 14 | -10 (7/8-14) | 22.23 mm / 14 | Same TPI; JIC is about 1.3 mm larger |
| G5/8 | 22.91 mm / 14 | -10 (7/8-14) | 22.23 mm / 14 | Same TPI and within 0.7 mm; check the thread angle and the seat |
| G3/4 | 26.44 mm / 14 | -12 (1-1/16-12) | 26.99 mm / 12 | Pitch differs |
| G1 | 33.25 mm (1.309 in) / 11 | -16 (1-5/16-12) | 33.34 mm (1.3125 in) / 12 | Diameter nearly identical; count threads |
| G1-1/4 | 41.91 mm (1.650 in) / 11 | -20 (1-5/8-12) | 41.28 mm (1.625 in) / 12 | Pitch differs |
| G1-1/2 | 47.80 mm (1.882 in) / 11 | -24 (1-7/8-12) | 47.63 mm (1.875 in) / 12 | Diameter nearly identical; count threads |
The G1 and G1-1/2 pairs are the hardest. Their diameters are within about 0.1 to 0.2 mm, which is less than caliper error on a worn thread. Only the pitch (11 vs 12 TPI) and the thread angle separate them. A 12 TPI gauge will not sit flat in an 11 TPI thread. You can also count threads over a full inch of length.
The G5/8 vs -10 JIC pair has the same 14 TPI. Here the 55° vs 60° thread angle and the seat (60° or flat vs 37°) are the best clues.
How to identify a BSP fitting
- Measure the thread OD with calipers, as shown in how to measure JIC fittings.
- Measure the pitch with a thread gauge. 28, 19, 14 and 11 TPI are BSP pitches. 19 and 11 TPI are not used on JIC fittings at all.
- Check the thread angle with a Whitworth (55°) gauge. If it sits flush and a 60° gauge rocks, it is BSP.
- Check for taper to separate BSPP from BSPT.
- Look at the seat. A 60° cone points to a BSPP hose end, and a flat face with a washer points to a BSPP port. A 37° cone means JIC.
The finder on the JIC identification page checks one diameter and pitch against JIC, BSP, NPT, ORFS and metric sizes at once.
Connecting BSP to JIC
Use an adapter with the correct BSP end and a male JIC end. For a BSPP port, choose an adapter with a bonded washer or O-ring seal on the BSP side. Do not use thread sealant on a parallel thread to make up for the wrong seal. Japanese JIS fittings use the same thread sizes as BSPP but a 30° seat; see JIC vs JIS.
References
Eaton Thread Identification Guide; McGill Hose thread identification guide; ISO 228-1 and ISO 7-1 thread dimensions as reproduced by these manufacturers; SAE J514 JIC dimensions as published by Parker and Eaton. Values are reference only.
Frequently asked questions
Is BSP the same as JIC?
No. BSP uses 55° Whitworth threads and seals on a 60° cone, a bonded washer or a tapered thread. JIC uses 60° UNF/UN threads and a 37° cone.
Which BSP size is closest to a -16 JIC?
G1 (1 in BSP) measures about 33.25 mm, almost the same as the -16 JIC 1-5/16-12 thread at 33.34 mm. The pitch differs: 11 TPI for BSP, 12 TPI for JIC.
How do I tell BSPP from BSPT?
Measure the male thread near the end and near the shoulder. If the diameter changes, it is tapered BSPT (R). If it stays the same, it is parallel BSPP (G).
Is 1/2 BSP the same as 1/2 NPT?
No. They are close in size, but BSP is 14 TPI with a 55° thread angle, and NPT is 14 TPI with a 60° angle and flat crests and roots instead of rounded ones. They are not designed to mate.
Can I use a JIC hose on a BSP port?
Only with an adapter that has a BSP end matching the port and a male JIC end for the hose.