Common residential PEX sizes
Brass PEX Ball Valves come in standard PEX diameters. The most popular sizes are 3/8-inch, 1/2-inch, and 3/4-inch. 1-inch valves are also common. Example: 1/2-inch fits most sink and toilet supplies.
3/8-inch valves for small fixtures
This size serves ice makers and coffee machines. It also works for some bidet seats. Brass PEX Ball Valves in 3/8-inch are compact. Example: a refrigerator water line needs this small valve.
1/2-inch valves for general use
Most residential fixtures use 1/2-inch PEX. Sinks, toilets, and dishwashers all use this size. Brass PEX Ball Valves in 1/2-inch are very common. Example: a bathroom vanity has two 1/2-inch valves.
3/4-inch valves for main lines
Main water lines entering a home are often 3/4-inch. Branch lines to water heaters also use 3/4-inch. Brass PEX Ball Valves at this size handle higher flow. Example: a whole-house shut-off valve is typically 3/4-inch.
1-inch and larger valves
Large homes and commercial buildings need 1-inch or 1-1/4-inch valves. Brass PEX Ball Valves up to 2 inches are available. Example: an apartment building main shut-off may be 1-1/2 inches.
What the size numbers mean
PEX size refers to the outside diameter of the pipe. 1/2-inch PEX has a 5/8-inch outside diameter. Brass PEX Ball Valves match this pipe dimension. Example: a 1/2-inch valve fits only 1/2-inch PEX pipe.
Crimp connection sizes
Crimp-style valves require matching crimp rings. The ring size must match the pipe size. Brass PEX Ball Valves list their connection type. Example: 1/2-inch crimp valve uses 1/2-inch crimp rings.
Compression connection sizes
Compression valves have a nut and ferrule. The nut size is larger than the pipe size. Brass PEX Ball Valves with compression ends fit PEX directly. Example: a 1/2-inch compression valve has a 3/4-inch nut.
Push-fit connection sizes
Push-fit valves insert directly into the pipe end. They come in the same nominal sizes. Brass PEX Ball Valves with push-fit ends are tool-free. Example: a 1/2-inch push-fit valve works in seconds.
Example: sizing for a bathroom group
A master bathroom has a toilet, two sinks, and a shower. Each needs a shut-off valve. Use 1/2-inch Brass PEX Ball Valves for all three. The shower valve is behind an access panel. Example: four identical valves simplify inventory.
Example: sizing for a whole house
A 2,500 square foot house has 3/4-inch main line. Use a 3/4-inch Brass PEX Ball Valve as the main shut-off. All branch lines reduce to 1/2-inch. Use 1/2-inch valves at each fixture. Example: two sizes cover the entire house.
Conversion between imperial and metric
PEX sizes are in inches for North America. Metric countries use millimeters. 1/2-inch equals approximately 16mm. Brass PEX Ball Valves in metric sizes include 16mm, 20mm, 25mm, and 32mm. Example: a European 16mm valve fits 1/2-inch PEX.
How to measure your pipe
Use a caliper to measure the outside diameter. Compare to a sizing chart. Brass PEX Ball Valves must match the pipe exactly. Example: 1/2-inch pipe measures 0.625 inches OD. Wrong size leads to leaks or no fit.
Final size selection guide
Brass PEX Ball Valves range from 3/8-inch to 2 inches. Use 1/2-inch for most fixtures. Use 3/4-inch for main lines and water heaters. Use 3/8-inch for ice makers and small appliances. Always verify your pipe size before buying. Choose the same connection type as your system. Keep spare valves in common sizes for emergencies. Example: a homeowner should stock one 3/4-inch and three 1/2-inch valves for quick repairs.