Flexible pipe

Here are the exterior diameters of the various flexible pipe sizes commonly found in spas and hot tubs:

• 1/2 inch: 21 mm (adapter to 20 mm available)
• 3/4 inch: 27 mm (adapter to 25 mm available)
• 1 inch: 33 mm (adapter to 32 mm available)
• 1.5 inches: 48 mm (adapter to 50 mm available)
• 2 inches: 60 mm (adapter to 63 mm available)

You will also find flexible hoses in metric sizes, although these are less common in the spa industry.