Miter Angle Calculator - Calculate Miter & Bevel Angles

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!

Real-time Calculation Multiple Joint Types Cutting Guides Professional Accuracy

Angle Parameters

Project Type

Frame Settings

Number of Sides

Frame Type

Crown Molding Settings

Spring Angle

Wall Angle

Custom Angle Settings

Desired Angle

Joint Type

Angle Results

Select project type and parameters to calculate precise miter angles for your woodworking project.

Safety: Wear safety equipment. Test cuts on scrap first. Double-check angles before cutting.

Disclaimer: Calculations are mathematical references. Verify saw calibration and test actual cuts before final work.

Professional Guide to Miter Angle Calculation & Precision Cutting

Accurate miter angle calculation ensures perfect joints in picture frames, moldings, polygon construction, and furniture making. Professional miter work requires understanding angle geometry, polygon formulas, compound cut calculations, and precision saw setup. This guide covers miter angle mathematics, common angle charts, compound miter techniques, and troubleshooting for perfect joints every time. Use our miter angle calculator for precise angle calculations in your woodworking projects.

Miter Angle Formulas & Polygon Calculations

Basic Miter Angle Formula

For Regular Polygons: Miter Angle = 180° ÷ Number of Sides

Polygon Type	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

Note: Formula: Miter Angle = 180° ÷ number of sides. This is mathematically precise for regular polygons (all sides equal).

Alternative Formula (Interior Angle Method)

Step 1: Calculate interior angle = (n - 2) × 180° ÷ n

Step 2: Miter angle = (180° - interior angle) ÷ 2

Octagon Example:

Interior angle = (8 - 2) × 180° ÷ 8 = 135°
Miter angle = (180° - 135°) ÷ 2 = 22.5°

Irregular Polygons & Custom Angles

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.

Compound Miter & Bevel Calculations

Compound Cuts: Require both miter angle (horizontal) and bevel angle (vertical) simultaneously.

Common Compound Cut Applications

Crown Molding: Spring angle 38° or 45° requires compound cuts
Hopper Joints: Angled box sides meeting at corners
Pyramid Structures: Slope angle determines compound settings
Angled Picture Frames: Shadow box frames with depth

Crown Molding Quick Reference (38° Spring Angle)

90° Inside Corner: Miter 31.6°, Bevel 33.9°

90° Outside Corner: Miter 31.6°, Bevel 33.9° (flip direction)

Pro Tip: Use our crown molding calculator for precise compound angle calculations based on your specific spring angle and wall angles.

Precision Saw Setup & Cutting Techniques

Miter Saw Calibration

Blade Square to Fence: Check with precision square, adjust if >0.002" deviation
Miter Gauge Accuracy: Verify detent stops at 0°, 45°, and 22.5° with digital angle finder
Fence Alignment: Both sides parallel, no gap at blade
Blade Condition: Sharp blade (60+ teeth) prevents tear-out on miters

Cutting Sequence for Perfect Joints

Professional Miter Cutting Process:

Test Cut: Always make test cuts on scrap matching project material
Nested Cuts: Cut longest pieces first, shortest last (allows re-cuts if needed)
Reference Face: Keep same face against fence for all pieces
Stop Blocks: Use for consistent length on multiple identical pieces
Backing Board: Zero-clearance backing prevents chip-out on exit side

For related angle calculations and woodworking techniques, see our joinery calculators and complete tools suite.

Frequently Asked Questions

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.