What Size Are Garden Hose Threads?

Garden hoses are essential pieces of equipment for outdoor maintenance, but understanding how they work can be tricky. Choosing the right size of garden hose thread isn't something to take lightly, as it will determine how the attachments and fittings fit. In this guide, you'll get an introduction to garden hose thread sizes to help you find the right one for your needs.

Understanding thread sizing

Before we dive into what size garden hose threads are, let's look at the basics of thread sizing. Threads measure the size and pitch of screws and hoses, and they're measured using two metrics: threads per inch (TPI) and inner diameter (ID).

Threads per inch, as the name suggests, refers to how many threads are present in an inch of the hose. The higher the number of threads, the finer the thread will be and a finer thread will lead to more secure attachments.

Inner diameters measure the diameter of the cylinders that make up the threads, and this affects how the threads fit together. You should always be sure to double check a hose's ID before different components of a hose system to ensure they fit together properly.

Common garden hose thread types

There are several different sizes and types of garden hose thread, and these include American National Standard (NST) or Fire Hose Thread, Garden Hose Thread (GHT), and British Standard Pipe (BSP).

NST/Fire Hose Threads

This thread is most commonly found on American fire hoses, and it has a male and female end. While NST has the same thread angle and pitch as National Pipe Tapered (NPT), the two are not compatible. NST is also interchangeable with British Standard Fire Hose Thread. The thread size for NST is 11.5 TPI.

Garden Hose Threads

This thread type is more commonly found in the US and Canada, and it has a female end only. The GHT thread angle is 55 degrees, and it also has 11.5 TPI. However, GHT has an ID that's slightly larger than NST, and the two are not interchangeable.

British Standard Pipe

This thread is most commonly seen in the UK and other parts of Europe, and consists of two threads: British Standard Pipe (BSP) and BSPT (BSP Thread). Both male and female ends are tapered at a 55-degree angle, but BSP has a 14 TPI thread size instead of 11.5.

Garden hose thread sizes

Now, let's take a look at the size measurements for garden hose threads. We've arranged the diameters for the three most common thread types (NST, GHT and BSP) in a simple table.

While the Children's Gas Mask Hose Threads (CGHT) are also sometimes used, they are more of an exception than the rule and are rarely seen today. As a result, we have not included it in this guide.

In Summary

Garden hoses come in a variety of different thread types and sizes, with the most common types being NST, GHT, and BSP. Pinpointing the thread size is the first step in shopping for correct garden hose fittings. With this guide, you should have the information you need to get the right size for your system!