5 Most Common PEX Fitting Sizes

PEX fitting is rarely needed since the PEX tubes do not have many leaks and breaks. PEX fittings are more durable and flexible compared to the traditional plumbing fittings. Although these fittings are mostly made up of brass, there are a few that are made up of plastic. PEX fittings have an extra coating layer which keeps them from developing rust or corrosion. There are a few sizes that are most commonly used.

1. ½” PEX Fitting

The ½” PEX fitting is the most common used fitting. It is used for most radiant heating installs like subflooring installs and concrete slabs.

2. ¾” PEX Fitting

The ¾” fitting is a common fitting used for snow melt systems.

3. 1” PEX Fitting

A 1” PEX fitting is used generally for return and supply lines to boilers or the radiant heating manifold. 

4. 3/8” PEX Fitting

The 3/8” fitting is used for residential radiant heating applications, such as kitchens and bathrooms.

5. 5/8” PEX Fitting

The 5/8” PEX fitting actually replaces the ½” tubing when a project calls for a heat load that is higher or flow rates. The 5/8” fitting is also able to substitute a ¾” fitting in projects that need more flexibility and less flow. Snow melt systems will be a good example of this replacement.