What Adapter For

How to connect PEX to copper pipe

Use a push-to-connect coupling, with no soldering, or a brass PEX x copper adapter soldered onto the copper. 1/2" PEX and 1/2" copper are both 5/8" across, so one 1/2" fitting takes either pipe.

What fits

A push-to-connect coupling, or a brass PEX x copper adapter

On the package: Push-to-connect coupling in your pipe’s size, e.g. 1/2 in.

PEX is made to copper tube size, so 1/2" PEX and 1/2" copper are both 5/8" across

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Push-to-connect coupling, copper, PEX and CPVC PEX x copper sweat adapter

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  • Shut the water off and drain the line before you cut anything.
  • No soldering: standard push-to-connect fittings (SharkBite’s tan collar) take copper and PEX in any combination, with the PEX stiffener built in. Cut each pipe square, deburr it, mark the insertion depth and push it in to the mark.
  • Soldered: a brass adapter with a copper end on one side and a PEX end on the other. Solder the copper side first, then the PEX joint, using an adapter made for your kind of PEX joint.
  • Uponor’s instructions keep solder and flame at least 18" from the PEX on the same line. Uponor also makes copper press adapters, which join with no flame at all.

The sizes match, but PEX joins with rings or fittings and copper usually with solder, so use a transition fitting.

More: Connecting different pipe

Picking the adapter

The PEX end of an adapter is made for one kind of PEX joint. Look at the PEX joints you already have (copper crimp rings, stainless clamps, or expansion rings stretched over the pipe) and choose an adapter with the same kind of PEX end.

Common questions

Can you solder PEX to copper?

No. Only the copper side of an adapter is soldered, and that's done before the PEX goes on.

Keep going

Connecting different pipeSharkBite fittingsGalvanized to copperWhat pipe do I have?Garden hose to 1/2" pipeGarden hose to 3/4" pipeConnect two garden hoses

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 Uponor, SharkBite and Copper Development Association.

See all 7 sources
  • Copper Development Association, Copper Tube Handbook (ASTM B88 tube dimensions)
  • Uponor, Plumbing Design Assistance Manual (PEX is copper tube size)
  • SharkBite (Reliance Worldwide), SharkBite Installation Guide (2020): pipe insertion depth table, integral PEX stiffener
  • SharkBite (Reliance Worldwide), Push-to-Connect Installation Guide (pocket guide): stiffeners, transition fittings, warnings
  • SharkBite (Reliance Worldwide), SharkBite PEX Installation Guide (2021): fits copper, CTS CPVC and PEX in any combination
  • Uponor, PEX Piping Systems Installation Guide, seventh edition (2025): ProPEX expansion fittings, pipe colors, copper and threaded adapters, no soldering within 18" of PEX
  • Uponor, PEX-a Installation Guide, second edition (2024): ASTM F876/F877, red and blue pipe (copy on a retailer server)

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.