Garden Hose Thread (GHT) vs NPT: Why Your Hose Won't Fit a Pipe

5 min read · updated Oct 2026

The short answer: Garden hoses use GHT (Garden Hose Thread), which is straight and seals with a rubber washer. Household pipes use NPT, which is tapered and seals on the threads themselves. Both get called "3/4 inch", but they have a different number of threads and a different size, so they won't connect without an adapter.

Why the confusion happens

Walk into any hardware store and you'll find "3/4 inch" hoses next to "3/4 inch" pipe fittings. It's natural to assume they fit together. They don't. The "3/4" is a name, not a measurement — a 3/4" garden hose thread is about 27 mm across, while a 3/4" pipe thread is about 26.7 mm and gets narrower toward the tip.

Side by side

	Garden hose (GHT 3/4")	Pipe (NPT 3/4")
Threads per inch	11.5	14
Outside size	About 27 mm (1.06")	About 26.7 mm (1.05"), tapering
Shape	Straight	Tapered (1 in 16)
How it seals	Rubber washer inside the female end	Threads wedge tight, with PTFE tape or paste
Tighten by	Hand	Wrench
Where you see it	Outdoor taps, hoses, sprinklers, washing machines (some)	Indoor plumbing, water heaters, pumps

What happens if you force them together

Because the thread spacing is different (11.5 vs 14 per inch), the threads only line up for a turn or so before they jam. Forcing past that point cross-threads the fitting: plastic strips, brass gets chewed up, and you end up with a connection that sprays water the moment you turn the tap on. Extra tape won't fix it.

How to tell which one you have

Look inside the female end. A flat rubber washer means garden hose thread.
Try to hand-tighten. Hose fittings seal hand-tight. Pipe fittings need a wrench.
Look at the shape. If the male thread gets slightly narrower toward the tip, it's NPT.
Count threads. Lay a ruler along the thread: 11.5 per inch is hose, 14 is pipe.
Check where it's used. Outdoors on a tap or hose? Almost certainly GHT.

A note for outside North America

GHT is a North American standard. In the UK, Europe and Australia, hoses usually connect with snap-on click connectors that screw onto a BSP tap thread (often 3/4" or 1/2" G). If you have an imported tap or hose, check the NPT vs BSP guide too.

How to connect a hose to a pipe

Use an adapter with a hose thread on one end and a pipe thread on the other. Remember the two ends seal differently: put a rubber hose washer in the hose side, and wrap PTFE tape on the pipe side only. If you can't find the exact adapter you need, you can print one — set one end to the pipe size you have and the other to match your hose.

Design your own adapter

Choose a thread for each end, set the lengths, and download a ready-to-print model with a full water passage.

Open the designer →