Size reference
110 sizes across 10 standards. Each size page carries the thread, the pitch, the basic diameters, what a caliper actually reads, the seat, what it mates with, and everything it can be mistaken for. Free, forever, all of it.
By standard
A straight Unified inch thread with a 37 degree metal cone seat. The most common hydraulic connection on North American equipment.
13 sizes60 degree flanksParallel37 degree flare cone
Also searched as: JIC, 37 degree flare, AN fitting, SAE 37. Defined by SAE J514, ISO 8434-2.
A straight Unified inch thread with a flat face and an O-ring in a groove on the male nose. The most leak-resistant of the common hydraulic connections.
8 sizes60 degree flanksParallelO-ring face seal (flat face)
Also searched as: ORFS, O-ring face seal, flat face O-ring, FFOR. Defined by SAE J1453, ISO 8434-3.
A straight Unified inch thread with an O-ring on a shoulder behind it, screwed into a port with a machined flat spotface. The standard port on North American pumps, valves and manifolds.
13 sizes60 degree flanksParallelO-ring boss (straight thread port)
Also searched as: ORB, SAE ORB, straight thread O-ring, SAE J1926, O-ring boss. Defined by SAE J1926-1, ISO 11926-1.
A straight Unified inch thread with a 45 degree metal cone seat. Shares its thread with JIC at several sizes, which is the single most common mis-identification in the trade.
8 sizes60 degree flanksParallel45 degree flare cone
Also searched as: SAE 45, 45 degree flare, flare fitting, SAE flare. Defined by SAE J512, SAE J533.
A 60 degree tapered pipe thread that seals on the thread flanks, normally with sealant or PTFE tape. NPTF is the dryseal version with crest and root interference.
10 sizes60 degree flanksTaperedTapered thread, sealed on the thread
Also searched as: NPT, NPTF, pipe thread, MPT, FPT, MIP. Defined by ASME B1.20.1, ASME B1.20.3.
A 55 degree Whitworth parallel thread that cannot seal on itself - the joint seals on a bonded washer, an O-ring or a cone at the face.
12 sizes55 degree flanksParallelParallel thread, sealed on a face gasket
Also searched as: BSPP, G thread, BSP parallel, BS 2779. Defined by ISO 228-1, BS 2779.
A 55 degree Whitworth tapered thread that seals on the thread flanks, the British counterpart to NPT. Interchangeable in size with BSPP but not in behaviour.
10 sizes55 degree flanksTaperedTapered thread, sealed on the thread
Also searched as: BSPT, R thread, Rc, BSP taper, BS 21, PT thread. Defined by ISO 7-1, BS 21.
A straight metric thread with a 24 degree internal cone, sealed by a cutting ring biting into the tube or by a soft seal captured in the cone.
20 sizes60 degree flanksParallel24 degree cone (DIN)
Also searched as: DIN 2353, 24 degree cone, metric bite type, DIN fitting, L series, S series. Defined by ISO 8434-1, DIN 2353.
A BSPP parallel thread with a 30 degree female cone seat, usually on a swivel nut. Reads as BSPP on a thread gauge, so the seat is the only thing that tells it apart.
9 sizes55 degree flanksParallel30 degree flare cone or seat
Also searched as: JIS 30, BSPP 30 degree, Japanese flare, JIS B 0202. Defined by JIS B 0202, ISO 228-1.
A straight metric thread with a 30 degree cone seat. The metric counterpart of the JIS 30 degree flare, and not interchangeable with it despite the identical seat.
7 sizes60 degree flanksParallel30 degree flare cone or seat
Also searched as: Komatsu, Komatsu flare, metric 30 degree flare, KOM. Defined by ISO 261, manufacturer catalogue dimensions.
Before you order
Several of these standards share a thread. A -08 JIC and a -08 SAE O-ring boss are both 3/4-16 UNF; a -08 SAE 45 degree flare is 3/4-16 as well. They will screw together happily and two of the three combinations will leak, because the sealing surface is different in each. The same trap sits between NPT and BSPT, which are close enough in diameter to start on each other and differ by five degrees of flank angle.
So every size page here prints the seat as prominently as the thread, and lists what the size can be confused with. Work through the identify flow if you have the fitting in your hand, or read the comparison pages if you already know which two you are choosing between.