Miter Angle Calculator

Find the miter saw angle for any regular polygon — picture frames, boxes, hexagons, and more.

Number of sides

Corner angle (°) (auto or custom)

Interior angle —

Miter angle (set saw to) —

Complementary (90° − miter) —

🛒 Shop related: Hardwood lumber · Hand tools · Clamps

For a regular polygon: interior angle = (n − 2) × 180° ÷ n. Miter angle = 180° ÷ n, which is half the exterior angle. Set your miter saw to this angle from the fence.

Common Miter Angles

Shape	Sides	Interior°	Miter°
Triangle	3	60.0°	60.0°
Square / Rectangle	4	90.0°	45.0°
Pentagon	5	108.0°	36.0°
Hexagon	6	120.0°	30.0°
Octagon	8	135.0°	22.5°
Decagon	10	144.0°	18.0°
Dodecagon	12	150.0°	15.0°

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How to Calculate Miter Angles

A miter joint connects two pieces at an angle. For a regular polygon (all sides equal), the miter angle is simply 180 divided by the number of sides. A square frame has 4 sides, so the miter angle is 180 ÷ 4 = 45 degrees.

For non-square corners (like a bay window or custom frame), you can enter the corner angle directly. The miter angle is half the supplement of the corner angle: miter = (180 − corner angle) ÷ 2.

On most miter saws, the angle scale reads from 0° (straight cut) to 45° or beyond. The "miter angle" result from this calculator is the angle to set on your saw fence.