Miter Angle Calculator

Find the miter cut angle for joining pieces into a polygon frame.

Miter angle (each cut) (°) 45

Interior corner angle (°) 90

Formula: miter = 90 × (n − 2) ÷ n; interior = 180 × (n − 2) ÷ n

Step-by-step with your numbers:

1. Values used:

2. Number of sides = 4

4. Miter angle (each cut) = 45°

5. Interior corner angle = 90°

Did we solve your problem today?

Building a picture frame, planter box or any equal-sided polygon? This finds the exact miter angle to set your saw for tight corners.

The math behind it

A polygon with n sides has interior angles of 180 × (n − 2) ÷ n.

Each of the two mating pieces is cut at half that angle: miter = 90 × (n − 2) ÷ n.

A 4-sided frame → interior 90°, miter 45° per cut. A hexagon (6 sides) → interior 120°, miter 60°.

Why 45° for a square frame?

Two 45° cuts meet to form the 90° corner of the square.