What Adapter For

What shutoff valve fits 1/2 inch PEX?

You need a 1/2" PEX x 3/8" compression angle stop whose inlet matches your PEX: crimp or expansion if you have the tools, or push-connect if you don’t.

What fits

1/2" PEX x 3/8" compression angle stop

On the package: 1/2 in. Nom Crimp PEX Barb x 3/8 in. O.D. Comp (or Cold Expansion PEX, or Push Connect)

crimp, expansion, or push-connect inlet

Available on Amazon

1/2" PEX x 3/8" compression angle stop

As an Amazon Associate, What Adapter For earns from qualifying purchases.

  • Shut off the water first. With no valve on this pipe yet, that usually means the house’s main shutoff. Open a faucet to let the pipe drain.
  • Crimp PEX and expansion PEX stops (BrassCraft makes both) are installed with PEX tools. Use the type that matches the PEX system you have.
  • Push-connect stops need no tools. BrassCraft’s fit copper, PEX and CPVC. Push it all the way to the depth mark.

PEX is copper tube size (1/2" PEX is 5/8" across) but soft, so choose the valve by its inlet type.

More: Supply line sizes

Keep going

SharkBite fittingspush-fitIs it 1/2" or 3/4" pipe?Shutoff valve sizeShutoff valve for copper pipeFaucet supply line sizeToilet supply line sizeGarden hose to 1/2" pipe

For a different part on either end, open the adapter finder with this pair picked.

Where we get our information from

The sizes on this page come from published standards and the makers’ own documents. Checked against published data from BrassCraft and Uponor.

See all 3 sources
  • Uponor, Plumbing Design Assistance Manual (PEX is copper tube size)
  • BrassCraft, angle stop product pages (compression, FIP, sweat, PEX and push-connect inlets; 3/8", 7/16", 1/2" and 1/4" O.D. outlets; 1/2" nominal = 5/8" O.D.)
  • BrassCraft, installation instructions for connectors (425.10, 425.07, B0120IMB) and water supply stops (425.04)

General guidance from manufacturer and standards data. Parts vary by brand, so check the size printed on the package against what you measured. For gas lines or anything inside a wall, use a licensed plumber.