📐 Miter Angle Calculator
Find the correct miter saw angle for joining two pieces of trim, molding, or frame at a given corner angle.
What this calculator does
The miter angle calculator finds the correct angle to set a miter saw so that two pieces of molding, trim, or framing meet cleanly at a corner, either for a regular polygon shape or for any custom corner angle.
The formula
For a regular polygon with n sides, the interior angle at each corner is (n − 2) × 180° ÷ n. For example, a standard square or rectangular corner (4 sides) has a 90° interior angle. The miter angle — the angle each piece is cut to, and the number you set on the saw — is half of the interior corner angle, since two matching cuts join to form the full corner. Many saws also show the complementary angle (90° minus the miter angle), which is provided as a cross-check.
- For a standard 90° corner, this gives the familiar 45° miter cut.
- Always cut a test piece first, since saw scales and material thickness can introduce small real-world variations.
This tool is for general woodworking and trim-carpentry planning.