Woodshop Miter Angle Calculator
Calculate miter and bevel angles for multi-sided frames, boxes, and crown molding. Find saw settings for hexagons, octagons, and compound cuts.
Built for Woodworking1 documented formulaFocused single-task workflowPrivate in your browser
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Inputs that matter
Number of Sides
Output to expect
Miter Angle Calculator
How it works
1 documented formula across 1 calculation mode
- Keep 1 bounded input within the limits shown beside the fields.
- Confirm that every value uses the unit and time basis shown before comparing scenarios.
- Change one input at a time to see which assumption materially changes the result.
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Reference & details
How it works
Updated July 2026
How it works
Updated July 2026Simple Miter Angle
For regular polygons where pieces meet flat, each miter is half the interior angle between adjacent sides.
Miter = 180° / N (where N = number of sides)Interior and Exterior Angles
Interior angle of a regular N-gon equals (N−2)×180°/N. The miter cut is half the supplement of the interior angle, which simplifies to 180°/N.
Interior angle = (N − 2) × 180° / NCompound Miter for Crown Molding
Crown sits at a spring angle (typically 38° or 45°) against the wall and ceiling. Compound miter requires both miter and bevel settings derived from the wall angle and spring angle.
Bevel = arctan(sin(Miter) × tan(Spring))Updated: July 2026
Example Scenarios
Six-sided box requires miter cuts at 30° on each end (180°/6). Each piece meets its neighbor at 120° interior angle for a closed hexagon.
Eight-sided frame needs 22.5° miter cuts (180°/8). Set miter saw to 22.5° left and right for alternating pieces.
Standard 52°/38° crown on a 90° inside corner uses miter 31.6° and bevel 33.9° on the saw (flat method) or 45° miter with crown nested at spring angle.
Common Mistakes to Avoid
Common Mistakes to Avoid
Using 360/N instead of 180/N for miter angle
The miter saw setting is half the corner angle: 180° divided by number of sides. Using 360/N gives the full corner angle, not the cut angle, and produces open joints.
Ignoring spring angle when cutting crown molding
Crown is not cut at 45° miter when nested at its spring angle. Use crown-specific angle charts or this calculator that accounts for the 38° or 45° wall-to-ceiling orientation.
FAQ
A regular hexagon uses 30° miter cuts on each end. Set your saw to 30° and cut equal-length pieces — six pieces form a closed hexagon with 120° interior corners.
Gaps usually come from pieces being slightly different lengths, saw not set exactly to 45°, or blade deflection. Test with scrap and verify the saw angle with a digital protractor.
Use compound settings for both miter and bevel. For 52°/38° crown on a 90° corner, typical flat-nesting settings are ~31.6° miter and ~33.9° bevel for inside corners.
A regular pentagon uses 36° miter cuts (180°/5). Interior angles are 108°, so each cut removes 36° from the end of each piece.
Simple four-sided frames need only a basic miter saw at 45°. Compound saws are needed for crown molding, sloped boxes, or any joint where pieces meet at non-90° three-dimensional angles.
About Woodshop Miter Angle Calculator
Cutting accurate miters for polygons, picture frames, and crown molding requires more than dividing 90° by the number of sides. This calculator provides miter saw settings for simple and compound angles for boxes, frames, and trim work.