How to Cut Baseboard Molding for Corners? | Cope Inside, Miter Outside

Inside corners get a coped joint — one board set square, the other cut at 45° and shaped with a coping saw — while outside corners take two 45° miters, and test cuts on scrap come first either way.

A baseboard run looks finished only if the corners meet tight, and the two corner types want two different cuts. Get the inside corner wrong and you get a gap filler can’t hide; get the outside corner wrong and the joint opens the first time the house shifts.

Inside Corners: Why A Coped Joint Beats A Miter

A coped joint is standard for inside corners because it stays tight even when walls aren’t square and seasonal movement pushes the boards together. A plain 45° miter leaves a visible seam that opens as the wood dries.

1. Cut the first piece square at 90° and nail it in place — the board the other dies into.
2. Cut the mating piece at 45° on the miter saw, angled so the profile is exposed.
3. Trim along the cut edge with a coping saw, following the molding profile — the flat back gets cut away and the front profile remains, so the coped edge sits flush over the first board.

To miter both sides of an inside corner instead, cut each at 45° so they meet. It’s faster, but the joint shows a hairline over time. Starting at 46° rather than 45° is the usual fix when a 45° cut leaves a gap on a corner that isn’t quite square.

Outside Corners And The Long-Point Rule

Outside corners are always mitered: both pieces at 45°, angled toward each other so the profiles meet at the protruding corner. There’s no coping equivalent that looks right outside.

That determines which way you lay the board on the saw and which point your tape hits.

Get that backwards and the board comes up short every time.

Handling Corners That Aren’t Square

Almost no corner in a real house is exactly 90°, so cut test joints on scrap first and adjust before touching the actual molding.

• Dry-fit scrap pieces in the corner and check for a gap at the front edge.
• If the miter doesn’t close, bisect the angle or bump the saw a degree or two and re-test.
• Measure each wall separately — never assume both walls of a corner are the same length.

The most common error is cutting the actual molding before proving the angle on scrap; the second is flipping the inside-versus-outside orientation, which is why the long-point rule is worth re-reading before every cut. If you’d rather not cut at all, snap-on baseboard corner molding trims that fit over the joint are a reasonable shortcut — compare the options in this roundup of baseboard corner molding picks.

Tools And Cutting Technique

A miter saw handles the 45° cuts and a coping saw does the profile work on inside corners.

Secure the workpiece before every cut — both saws demand the board can’t shift. Keep the blade path clear of your hands and let the saw do the work rather than forcing it. Sharp coping blades make a clean profile line; a dull one tears the edge and shows in the finished joint. Thisiscarpentry’s install walkthrough and The Spruce’s coping-vs-mitering guide both treat scrap test cuts as non-negotiable, and DAP’s install guide covers the same inside-and-outside corner split.