Our shower head is knackered, so I unscrewed the offending article and measured it. Simples I thought. No it flipping isn't.
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.)
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.)