Hose and Irrigation Thread Reference Chart (GHT, NPT, BSP)
Use this page to answer one question: what adapter turns the thread I have into the thread I need? Garden hose thread seals on a washer and is straight. Pipe thread seals on the threads and is tapered. Everything else follows from that.
1. Thread specification table
| Designation | Also called | Nominal size | TPI | Taper | Thread angle | Seals on |
|---|---|---|---|---|---|---|
| GHT | NH, NHR, garden hose thread | 3/4" | 11.5 | Straight | 60° | Flat washer |
| GHT | NH (large, uncommon) | 1" | 11.5 | Straight | 60° | Flat washer |
| NPT | National Pipe Taper, MPT/FPT | 1/8" | 27 | Tapered 1:16 | 60° | Thread flanks |
| NPT | 1/4" | 18 | Tapered 1:16 | 60° | Thread flanks | |
| NPT | 3/8" | 18 | Tapered 1:16 | 60° | Thread flanks | |
| NPT | 1/2" | 14 | Tapered 1:16 | 60° | Thread flanks | |
| NPT | 3/4" | 14 | Tapered 1:16 | 60° | Thread flanks | |
| NPT | 1" to 2" | 11.5 | Tapered 1:16 | 60° | Thread flanks | |
| NPS / NPSH | Straight pipe, hose coupling | 1/2" – 3/4" | 14 | Straight | 60° | Gasket or O-ring |
| BSPP | G, parallel BSP | 1/2" & 3/4" | 14 | Straight | 55° | Bonded washer / O-ring |
| BSPP | G | 1" – 2" | 11 | Straight | 55° | Bonded washer / O-ring |
| BSPT | R, tapered BSP | 1/2" & 3/4" | 14 | Tapered 1:16 | 55° | Thread flanks |
| M22 | Pressure washer outlet | 22 mm, 1.5 mm pitch | — | Straight | 60° | O-ring on a 14 mm or 15 mm insert |
| S60x6 | IBC tote buttress | 60 mm | — | Straight coarse | Buttress | Flat gasket |
Two traps. 1" NPT and 3/4" GHT are both 11.5 TPI — count alone will not identify a thread, you also need the diameter. And 3/4" NPT and 3/4" BSP are both 14 TPI — they will start, then leak, because the flank angle differs.
2. Identify what you have
| Observation | Conclusion |
|---|---|
| Female end has a flat internal shoulder holding a rubber washer, and swivels | Female hose thread (FHT) |
| Male crests are parallel along a straight edge | GHT, NPS or BSPP |
| Male crests narrow toward the tip | NPT or BSPT |
| Male OD about 1-1/16" (1.0625"), coarse thread | 3/4" GHT male |
| Male OD about 1.050" at the base, tapering, 14 TPI | 3/4" NPT male |
| Stamped G, e.g. G3/4 | Parallel BSP — needs a bonded sealing washer |
| Stamped R, e.g. R3/4 | Tapered BSP — seals on the threads |
3. Adapter selection by job
| Job | Thread on the equipment | Adapter needed | Sealant |
|---|---|---|---|
| Outdoor spigot / hose bib | 3/4" MHT | None | Washer only |
| Water heater drain valve | 3/4" MHT | None | Washer only |
| Utility sink or standpipe | 1/2" or 3/4" FNPT | MHT × MNPT nipple | Tape on the NPT end only |
| Transfer / utility pump port | 3/4" or 1" FNPT | MHT × MNPT | Tape on the NPT end only |
| Compressor moisture trap | 1/4" FNPT | 1/4" MNPT × FHT | Tape on the NPT end only |
| IBC tote outlet | S60x6 | S60x6 × 3/4" MHT | Supplied gasket |
| Pressure washer inlet | 3/4" FHT | None | Washer only |
| Pressure washer outlet | M22 (14 or 15 mm insert) | M22 × 3/8" quick-connect | O-ring |
| Drip irrigation header | 1/2" or 3/4" barb / compression | FHT swivel × barb start connector | Washer only |
| Rain barrel bulkhead | 3/4" FNPT | MNPT × MHT spigot | Tape on the NPT end only |
| Sprinkler riser | 1/2" or 3/4" FNPT | MNPT × FHT swivel | Tape on the NPT end only |
| Soaker hose run | 3/4" FHT | None — use a hose washer and a pressure regulator | Washer only |
4. Method note
Threads per inch are counted over one inch of thread with a pitch gauge or a steel rule laid along the crests. Taper is verified against a straight edge, not by eye. Nominal pipe sizes refer to a legacy bore dimension, not to any measurable outside diameter — a 3/4" NPT male fitting measures about 1.05" across the crests, which is why nominal size can never be measured directly with a tape. Where a source disagrees with the stamp on the part in your hand, believe the part.
5. Frequently asked
Is garden hose thread the same as 3/4 inch NPT?
No. Garden hose thread (GHT, also written 3/4"-11.5 NH) is a straight thread with 11.5 threads per inch that seals against a flat rubber washer. 3/4" NPT is a tapered thread with 14 threads per inch that seals on the thread flanks with PTFE tape or pipe dope. They are close in diameter, which is why they cross-thread, but they are not interchangeable. Use an FHT x MNPT or MHT x FNPT adapter.
Can I use PTFE tape on a garden hose thread?
No. Hose threads seal on the washer inside the female coupling, not on the threads. Tape only holds the sealing faces apart. If a hose connection weeps, replace the washer.
Why does my BSP fitting leak in an NPT port?
Both 1/2" and 3/4" BSP and NPT use 14 threads per inch, but BSP uses a 55 degree thread angle and NPT uses 60 degrees. The fitting will start and even tighten, then leak. Use a labelled BSP-to-NPT adapter instead.
What thread is a pressure washer inlet?
The water inlet on almost all consumer pressure washers is 3/4" female hose thread, so a garden hose connects directly. The high-pressure outlet is usually M22 (with either a 14 mm or 15 mm insert) or a 3/8" quick-connect, and those two are not interchangeable without an adapter.
What fits an IBC tote outlet?
Most IBC totes use an S60x6 coarse buttress thread on a 60 mm outlet. An S60x6 to 3/4" male hose thread adapter converts it to a standard garden hose. Some totes use a 2" camlock instead, so check the valve before ordering.
Shop the fittings
Hose fittings, connectors and nozzles · Garden hoses · Drip irrigation · Sprinklers · Hose timers · Rain barrels · Watering cans and hose reels. Free US shipping.
Related reading: GHT vs NPT explained.
Aftermarket and OEM-compatible parts. PatioZora is not affiliated with or endorsed by the brands named on this page; brand names are used to indicate fitment only. Figures on this page are published reference standards and general guidance — always confirm against the stamp, plate or manual on your own equipment.