Miter Saw Angle Calculator
Find the exact miter and bevel angles to set on your miter saw for polygon frames, inside corners, and crown molding compound cuts. Use it any time you need precise angle settings beyond a basic 45°.
Last updated: September 2026
Formula below · 2 sources (fpl.fs.usda.gov, Wikipedia) · Updated Sep 2026
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About this calculator
For a flat regular polygon frame (picture frame, box or table top) each corner is shared by two cuts, so the miter saw setting, measured from a square crosscut, is miterAngle = 180 / numberOfSides: 45° for 4 sides, 30° for 6, 22.5° for 8. For crown molding laid flat on the saw around the corners of an N-sided room, each wall corner has an interior angle of 180 − 360/N degrees, and the miter setting is: miter = atan(sin(springAngle) / tan(cornerAngle / 2)), where the spring angle is the angle between the back of the molding and the wall (38° for standard 52/38 crown, 45° for 45/45 crown). For a square room with 52/38 crown that gives 31.6°; the matching blade bevel is asin(cos(springAngle) × cos(cornerAngle / 2)) = 33.9°. Material thickness does not change these angles. Always test on scrap before cutting your final workpiece.
How to use
Example: an octagon (8-sided) picture frame. Enter numberOfSides = 8, project type Picture Frame/Box, spring angle Not applicable. Miter = 180 / 8 = 22.5°; set the saw to 22.5° with 0° bevel and cut both ends of all 8 pieces as mirror cuts. For a hexagon: 180 / 6 = 30°. Crown molding in an ordinary 4-cornered room: numberOfSides = 4, project type Crown Molding, spring 38°: miter = atan(sin 38° / tan 45°) = 31.6°, with a 33.9° bevel.
Frequently asked questions
What miter angle do I need for a hexagon picture frame?
A regular hexagon has 6 sides and six 120° corners. The miter saw setting on each end of each piece is 180 / 6 = 30°. Set your saw to 30° and cut both ends of all six pieces as mirror cuts. When assembled, the six joints close into a hexagon. Always cut a test piece first to confirm your saw's detent is accurate at 30°.
How do I calculate crown molding miter and bevel angles for a corner?
Crown molding sits at a spring angle relative to the wall, which means a simple flat miter will not produce a tight fit — you need a compound cut combining a miter angle and a bevel angle. This calculator uses the spring angle and material thickness to compute the bevel correction via arcsin(sin(springAngle) × sin(materialThickness)). Common spring angles are 38° and 45°; check the back of your molding or the manufacturer's spec. Many woodworkers also use the flat-on-the-table method to avoid bevel settings entirely.
Why do inside and outside polygon corners require different miter angles?
For a regular polygon frame the two cuts at each corner are identical whether you think of the corner from the inside or the outside: the setting is 180 / sides in both cases. What changes is which face of the molding goes against the fence and which way you swing the saw. For crown molding, inside and outside corners use the same miter and bevel numbers, but the molding is placed on the opposite side of the blade.