Free miter angle calculator for perfect cuts. Calculate miter angles and bevel angles for frames, crown molding, and polygon projects. Includes compound miter calculations and cutting guides. Get precise angles for picture frames, baseboards, and complex joints!
Select project type and parameters to calculate precise miter angles for your woodworking project.
For Regular Polygons: Miter Angle = 180° ÷ Number of Sides
Step 1: Calculate interior angle = (n - 2) × 180° ÷ n
Step 2: Miter angle = (180° - interior angle) ÷ 2
For irregular shapes with varying angles, each corner requires individual calculation. Measure the actual corner angle and divide by 2 to get the miter angle.
| Polygon | Sides | Miter Angle | Interior Angle | Common Uses |
|---|---|---|---|---|
| Triangle | 3 | 60° | 60° | Decorative accents |
| Square/Rectangle | 4 | 45° | 90° | Picture frames, boxes |
| Pentagon | 5 | 36° | 108° | Decorative panels |
| Hexagon | 6 | 30° | 120° | Tabletops, tiles |
| Octagon | 8 | 22.5° | 135° | Tables, mirrors |
| Decagon | 10 | 18° | 144° | Specialty frames |
| Dodecagon | 12 | 15° | 150° | Clock faces, decorative |
Miter Angle = 180° ÷ Number of Sides Compound Cuts: Require both miter angle (horizontal) and bevel angle (vertical) simultaneously.
The angle at which a saw cuts across the width (face) of a board. Set on the miter gauge or turntable. For a 90° corner, each piece gets a 45° miter cut.
The angle at which the saw blade tilts through the thickness of a board. Set on the bevel adjustment. Combined with miter angle for compound cuts.
A cut requiring both miter and bevel angles simultaneously. Used for crown molding, hopper joints, and angled frames where pieces meet at complex angles.
The angle at which crown molding rests against the wall/ceiling junction. Common values: 38° and 45°. Determines the compound miter and bevel needed.
The angle inside a polygon at each vertex. For regular polygons: (n-2) × 180° ÷ n. The miter angle is derived from the interior angle.
The width of material removed by a saw blade during cutting. Typically 1/8" for standard blades. Must be accounted for in precise miter work.
A pre-set position on a miter saw where the blade locks at common angles (0°, 15°, 22.5°, 30°, 45°). Convenient but should be verified with a digital angle finder.
An angled splice joint where two pieces are beveled and overlapped end-to-end. Used to join pieces along a wall where a butt joint would be visible.
For rectangular frames, use 45° miter cuts at each corner. For other polygons, divide 180° by the number of sides to get the miter angle. For example, an octagon requires 22.5° cuts (180° ÷ 8 = 22.5°).
A miter cut is angled across the width of the board (horizontal plane), while a bevel cut is angled through the thickness (vertical plane). Compound cuts combine both miter and bevel angles.
Crown molding requires compound miter cuts. The spring angle (typically 38° or 45°) and wall angle determine the miter and bevel settings. Use our crown molding calculator for precise angles based on your specific molding profile.
Common causes include: inaccurate angle calculations, saw blade not perpendicular to the table, fence not square, or material movement during cutting. Always test cuts on scrap wood and verify saw calibration.
Essential tools include: miter saw or miter box, digital angle finder, combination square, precision ruler, and sharp blade. For crown molding, consider a compound miter saw with positive stops.
For professional results, aim for accuracy within 0.1°. Small errors compound across multiple joints. Use digital tools when possible and always verify calculations with test cuts on scrap material.