What Adapter For

What shutoff valve fits 1/2 inch copper pipe?

You need a 1/2" nominal compression x 3/8" compression angle stop. “1/2 inch” copper is 5/8" across, so the valve must say nominal; one marked 1/2" O.D. won’t fit.

What fits

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

On the package: 1/2 in. Nom Comp x 3/8 in. O.D. Comp

1/2" nominal = 5/8" O.D.; or a sweat or push-connect inlet

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

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  • 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.
  • The pipe end must be square, round and free of burrs.
  • Compression inlet slides over the copper with a nut and ring, with no soldering. No thread tape. Tighten it by hand, then 3/4 turn with a wrench. BrassCraft labels it “1/2 in. Nom Comp” (5/8" O.D.).
  • Push-connect inlet pushes onto the pipe. BrassCraft’s push-connect stops fit copper, PEX and CPVC. Push it all the way to the depth mark, since stopping short can leak.
  • Sweat inlet is soldered on.
  • An angle stop is the usual choice where the pipe comes out of the wall.

“1/2 inch” copper is 5/8" across, so a valve marked 1/2" O.D. won’t fit it. Use the one marked 1/2" nominal.

More: Supply line sizes

Keep going

SharkBite fittingspush-fitIs it 1/2" or 3/4" pipe?Shutoff valve sizeShutoff valve for PEXFaucet supply line sizeIdentify itcopper or not?Garden 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 Copper Development Association.

See all 3 sources
  • Copper Development Association, Copper Tube Handbook (ASTM B88 tube dimensions)
  • 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.