How to Cut 3/8 Copper Tubing? | Skip the Hacksaw

Cut 3/8 copper tubing cleanly with a tubing cutter sized to the outside diameter, then deburr the fresh edge before assembling.

For the full breakdown, see our best 3/8 Metal Tubing guide.

A hacksaw will get through 3/8 copper tubing, but it usually leaves a burred, angled edge that fights the fitting. Before the first mark, learn how to cut 3/8 copper tubing with the tool made for the job: a tubing cutter matched to the tube’s outside diameter (OD). The cutter scores a square line, keeps the tube round, and leaves far less cleanup than a saw blade.

Why Not Just Use a Hacksaw?

A hacksaw can do the job, but it is the slower, rougher path. It cuts acceptably when the pipe is locked in a vise, clamp, or miter box, yet even then the end tends to arrive less square, and the burrs need work before a fitting will slide on smoothly. A tubing cutter sized for the tube’s OD gives a cleaner, squarer cut in seconds and reduces the burrs that interfere with fittings.

Sizing matters more than brand. Ridgid’s tubing cutter lineup includes models with cutting ranges of 1/8″ to 3/8″ and telescopic cutters that reach 1/8″ to 1-3/8″, so 3/8-inch copper sits comfortably inside either. Measure the outside diameter before you pick, because a cutter built for bigger pipe will not seat properly on a 3/8-inch tube.

Cutting 3/8 Copper Tubing: Mark, Score, Rotate, Repeat

The sequence is identical on every manual cutter and takes about half a minute once the tube is marked. Shut off the water first if the tube is installed in place — residual leakage is normal — and treat the cut edge as sharp, because it will be.

1. Measure the outside diameter and mark the cut line. A cutter whose listed range covers 3/8 inch, such as 1/8″–3/8″, will seat correctly.
2. Open the cutter, place the tube between the cutting wheel and the rollers, and line the wheel up exactly with the mark. Keep the cutter square to the tube.
3. Tighten the knob until the wheel just touches the copper, then rotate the cutter around the tube in one smooth direction.
4. After every few rotations, tighten the knob slightly — a quarter turn is plenty — and keep rotating. The wheel scores deeper on each pass until the tube separates. Tightening too much too soon deforms the copper and can leave the tube out of round, which makes fitting installation difficult.
5. Deburr the cut end with the cutter’s built-in reamer or a separate deburring tool or round file, working until the inner lip feels smooth. A burr left on the inside edge can restrict flow and scratch the fitting during assembly.

Home Depot’s guide to cutting pipe and tubing describes the same loop: score, rotate, tighten slightly, repeat, then deburr. Powered options exist for bigger jobs, too — Milwaukee’s M12 Copper Tubing Cutter (2471-20) is rated for Type K, L, and M copper pipe from 3/8″ to 1″. Just check the range on automatic cutters: one demo of a small copper cutter notes that it “bottoms out at 3/8,” meaning some tools only handle tubes of that size or larger.

Common Mistakes and How to Avoid Them

Nearly every failed cut traces back to four fixable errors: the wrong cutter size, tightening too much too soon, skipping the deburr, and letting the cutter drift off the mark.

When the project calls for new tube rather than cutting what is already on hand, the stock matters as much as the cut. If you are comparing 3/8 metal tubing for a water line, fridge connection, or repair, our tested roundup of 3/8 metal tubing options sorts the worthwhile buys from the cheap failures. For plumbing, copper pipe typically comes in Type K, L, and M, and all three cut the same way with the same cutter.