Standard Fittings

The good news:

Conveniently, there has long been a standard size for shower fittings in the United States. All of our shower heads and shower arms meet this standard. Also, this means all our shower heads and shower arms are compatible with any other standard heads or arms, and you can easily replace just a shower head if you like and keep your existing shower arm. Similarly, you can keep your current shower head if you like and upgrade just the shower arm. It is highly unusual to find shower heads and arms already installed that are not the standard size.

The standard size and threading is called 1/2" NPT (for 'National Pipe Thread - Tapered). It is also referred to as MNPT, MPT or NPT(M) for male threads, and FNPT, FPT or NPT(F) for female threads.

The bad news:

Standard 1/2" fittings won't be 1/2" in any dimension if you measure them, and this can cause confusion. Many customers will be sure they don't have standard fittings since they measured their existing shower head or shower arm and they measured around 5/8" or 3/4". But most 1/2" male fittings will actually measure about 0.8" in outside diameter, and 1/2" female fittings will be around 1" outside diameter. (Why is this the case? For the same reason that in lumber a 2x4 isn't actually 2" x 4". Someone decided a long time ago that is how it would be, and that was that.)