Crown molding angles
The miter and the bevel for any corner and any spring angle. A square corner with 38° crown is 31.6° and 33.9° — and if your corner is not square, this is what it becomes.
A square corner is 90°
The common one. Sold as 38/52 — 38° off the wall, 52° off the ceiling.
Saw settings — inside corner, laid flat on the table
Miter
31.6°
Swing the saw head
Bevel
33.9°
Tilt the blade
Or cut it nested — held upside down against the fence at its spring angle, blade straight up — and it is a single setting: 45.0° miter, 0° bevel. Nesting is faster and harder to get wrong. Cutting flat is the only option once the molding is too tall to stand up against your fence.
Which half is waste
On an inside corner the long point of the miter is at the back of the molding — the face is the short side. Get that backwards and the joint opens at the front, where you can see it.
Cut a pair of short offcuts at these settings and hold them into the corner before you touch a full length. Two minutes of scrap is cheaper than eight feet of molding, and it catches the case where the wall is not the angle you measured.
Don't know the spring angle?
Stand the molding in a square corner the way it will be installed, or hold a framing square against it. Measure how far it drops down the wall and how far it reaches across the ceiling.
About cutting crown molding
- What are the miter and bevel settings for 38° crown in a square corner?
- 31.6° miter and 33.9° bevel, cutting the molding flat on the saw table. For 45° crown it is 35.3° miter and 30° bevel. These two pairs cover most of the crown molding sold, which is why they are printed on the side of a lot of miter saws.
- What is a spring angle?
- The angle between the back of the molding and the wall. Crown does not lie flat against either the wall or the ceiling — it bridges the two — and the spring angle says how it leans. 38° crown drops further down the wall than it reaches across the ceiling; 45° crown does both equally. If you do not know yours, stand the molding in a square corner, measure the drop down the wall and the reach across the ceiling, and the spring angle is the arctangent of reach over drop.
- Why can't I just cut crown at 45°?
- Because the joint is not in the plane of the molding. A picture frame lying flat meets at 45° because both pieces are in the same plane as the cut; crown is tilted out of that plane by its spring angle, so the cut plane is tilted relative to the molding in two directions at once. Cut crown at 45° flat and you get a joint that is visibly open at the top or the bottom, depending which way you were wrong.
- Should I cut crown flat or nested?
- Nested is easier and harder to get wrong: the molding is held upside down against the fence at its spring angle, so the fence stands in for the wall and the table for the ceiling, and you only set the miter. The catch is capacity — once the molding is too tall to stand up against your fence, nesting stops being an option and you have to cut it flat with both settings dialled in.
- My corners aren't 90°. Does that matter?
- Yes, and more than for almost any other trim. Crown magnifies a corner error because the joint is long and it sits at eye level. Measure the actual angle with a protractor or an angle finder and enter it — a corner that is 88° instead of 90° moves the miter by about half a degree, which is the difference between a tight joint and one you can see across the room.
- Why do carpenters cope inside corners instead of mitering them?
- Because a coped joint tolerates a wall that is not square and a house that moves. One piece is cut square into the corner and the other is cut to the profile of the first, so the joint closes even when the corner is out, and it stays closed when the framing shrinks in the first winter. Outside corners have to be mitered — nothing to cope to — which is where these settings earn their keep.
You might also need
- Wainscoting layoutEven picture-frame boxes across a wall, drawn as an elevation with the cut lengths underneath.
- Picture frame miter cutsCut lengths, long point to long point, for a rectangular mitered frame, and how much molding to buy.
- Segmented rings and columnsMiter and bevel for any number of sides, flat or flared, and how long each segment has to be.
- Wood movementHow far a panel expands and shrinks with the seasons, and what that means for the joint holding it.
- Miter angle calculatorThe miter for baseboard, casing or chair rail at any corner angle — flat trim, so there's no bevel to set.