Crown molding angle calculator
Enter the angle of your corner and the spring angle of your molding. Get the exact miter and bevel to set on the saw, plus a diagram showing how to lay the molding down. Built to handle odd corners, not just a square 90.
The four corner cuts
These are the saw settings for cutting flat, face up, with the ceiling edge against the fence. Always make a test cut on a scrap and dry-fit it before running a full length. Most real corners are a degree or two off square, so measure yours.
How the crown molding calculator works
Crown molding sits at an angle to both the wall and the ceiling, so a corner joint is a compound cut: the saw table rotates to a miter angle and the blade tilts to a bevel angle, both at once. A flat 45 degree miter, the instinct most people reach for, never closes the seam, because it ignores the way the molding springs off the wall.
For a square 90 degree corner with common 38 degree spring crown, the settings are a 31.6 degree miter and a 33.9 degree bevel. These are so standard that many saws have detents stamped right at those marks.
Source: Family Handyman, "The secret numbers for cutting crown flat" (familyhandyman.com), and Rockler crown molding cutting tips (rockler.com).The math takes two inputs: the corner angle between your two walls, and the spring angle of the molding (the angle its back makes with the wall, usually 38, 45, or 52 degrees as marked). From those it returns the miter and bevel using the standard compound-miter relations. The miter is the arctangent of the cosine of the molding's tilt off the table times the tangent of half the corner; the bevel is the arcsine of the sine of that tilt times the cosine of half the corner. Enter a corner that is not 90 and the numbers change accordingly, which is exactly where fixed charts and most paid apps fall down.
New to this? Read how to cut crown molding flat, learn about the spring angle, or see how to handle odd corners.
Frequently asked questions
What miter and bevel do I set for crown molding on a 90 degree corner?
For the most common crown with a 38 degree spring angle on a square 90 degree corner, set the saw to a 31.6 degree miter and a 33.9 degree bevel, cutting the molding flat. A 45 degree spring needs 35.3 miter and 30 bevel; a 52 degree spring needs 38.2 miter and 25.8 bevel. This calculator returns the exact pair for your corner and spring angle.
How do I cut crown molding for a corner that is not 90 degrees?
Measure the real angle between the two walls with an angle finder, then enter that number as the corner angle. The calculator recomputes the miter and bevel for any corner from just over 0 up to almost 180 degrees, which is the part fixed-angle charts and most apps get wrong.
What is the spring angle and where do I find it?
The spring angle is the angle the back of the molding makes with the wall once it is installed. It is usually printed on the molding or its box as 38, 45, or 52 degrees. If it is not marked, set a piece in place against a square and measure the gap, or test a guess against a scrap cut.
Is cutting flat better than cutting nested?
Cutting flat lays the molding face up on the saw table with a compound miter and bevel. It works on any saw, handles long pieces, and is the only practical way to cut odd corners, which is why this tool uses it. Nesting the molding against the fence at its spring angle also works for square corners but does not scale to out-of-square walls.
Why does the bevel matter? My old saw only does miter.
Crown sits at an angle to both the wall and the ceiling, so a single flat miter never closes the joint. Cutting flat needs both the table rotation (miter) and the blade tilt (bevel) at once. If your saw cannot bevel, cut the molding nested against the fence instead and use only the miter, but you lose the odd-corner flexibility.