Miter Angle Calculator
Get the compound miter and bevel angles for crown molding at any corner angle.
Compound miter (saw angle)
How compound miter and bevel angles are calculated
Crown molding sits at an angle (the "spring angle") between the wall and ceiling rather than lying flat, which is what makes cutting it different from baseboard or flat trim. To cut it while it lies flat against the miter saw table (the "lay flat" method most trim carpenters use), the saw needs both a miter angle (the horizontal rotation) and a bevel angle (the blade tilt) working together — a compound cut.
This calculator uses the standard trigonometric relationship for compound crown cuts. With the spring angle measured from the wall as S = 90° − spring angle, and half the wall corner angle as H = corner ÷ 2: Miter angle = arctan(cos(S) × tan(H)) and Bevel angle = arcsin(sin(S) × sin(H)).
For the most common case — a standard 90° square corner with 38° crown — this works out to roughly a 31.6° miter and 33.9° bevel, and for 45° crown at a 90° corner, roughly a 35.3° miter and 30° bevel, matching the values published on standard compound-crown-molding reference charts used throughout the trim carpentry trade.
Where these numbers come from
The formula and default values in this calculator are based on:
- Compound miter/bevel trigonometric formulas match standard published crown molding cutting charts (e.g. the widely used 90°-corner, 38°/45°-spring reference tables found in trim carpentry references and saw manufacturer guides).
These are planning estimates. Check your local building code, product specifications, and a licensed contractor before you buy materials or build.
Frequently asked questions
What is a spring angle and why does it matter?
The spring angle is the angle the crown molding's back sits away from the wall (or, equivalently, the angle it springs up from horizontal). The two most common stock crown profiles are made to a 38° or 45° spring angle, and that angle directly changes both the miter and bevel numbers you need to cut it correctly.
Why does crown molding need two angles instead of one?
Because crown sits at an angle rather than flat against the wall, a single miter cut (like you'd use on flat baseboard) won't produce a clean joint at the corner. The compound cut combines a horizontal miter rotation with a vertical blade tilt (bevel) to account for the molding's spring angle.
Does this work for corners other than 90 degrees?
Yes -- enter your actual wall corner angle (measured with an angle finder) and the calculator recalculates both the miter and bevel for that angle, which is useful for out-of-square corners or intentionally angled walls, not just standard square rooms.
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