Hydraulic Fitting Identifier
ReferenceIdentify common SAE, BSP, JIS, and DIN hydraulic threads from diameter, pitch, and seat.
Not sure what to check first? Hand the result to the assistant.
About this tool
A mismatched hydraulic fitting can leak, strip, or separate under pressure. This identifier matches male-thread outside diameter, pitch, and seat type against common JIC 37 degree, SAE 45 degree, JIS 30 degree, DIN 24 degree, ORB, ORFS, NPT, BSP, and metric threaded families.
Measure the male thread across the crests with calipers, determine TPI or metric pitch, and inspect the sealing surface. Diameter alone is not enough: multiple families share a thread but use different flare angles, cones, O-rings, or tapered seals.
The trickiest pair is NPT versus BSP: their diameters nearly overlap, but the thread pitch differs - 1/4" NPT is 18 TPI while 1/4" BSP is 19. At sizes that share TPI, also compare the 55 degree BSP and 60 degree NPT thread forms. Thread dimensions here are the published SAE, ISO, and DIN standard values; confirm the final selection against the component before you assemble a pressure line.
SAE J518 Code 61/62 and similar split flanges are not threaded fittings. Identify those separately from flange-head diameter, bolt-hole spacing, port size, and pressure series.
Frequently asked questions
How do I measure hydraulic fitting thread size?
Measure the male thread's outside diameter across the crests. If you only have a female port, measure its inside diameter and expect the mating male to be slightly larger, or match a known male fitting to it.
What is the difference between JIC and ORB (O-ring boss) fittings?
By the seat. JIC seals on a 37° cone (flare) at the tip; SAE O-ring boss has a straight thread and seals with an O-ring against the face of the boss. Same thread size, different seal - pick the seat type and the tool separates them.
How do I tell NPT from BSP threads?
Count the threads per inch. The diameters are close, but 1/4" NPT is 18 TPI and 1/4" BSP (G/R) is 19; 1/2" NPT is 14 and 1/2" BSP is 14 but the thread angle differs (60° vs 55°). Use TPI plus the 55 degree BSP versus 60 degree NPT thread form; some sizes share the same TPI.
What is a dash size?
The dash number (-4, -6, -8…) is the fitting size in sixteenths of an inch of the nominal tube or hose it serves. A -8 JIC is for 1/2" tube. The tool shows the dash size next to the matching thread.
Why do I get more than one match?
Because several families can share a diameter. Add the TPI and seat type to narrow it to one. If it's still ambiguous, compare the physical seat (cone, flat O-ring face, or tapered pipe) against the list.