Miter Angle Calculator
Find your saw setting for any corner joint
How to use this miter angle calculator
For a standard corner (like a square picture frame), leave it on “By Corner Angle” and enter 90° — that’s the default. For anything with more than four sides (hexagon planters, octagon frames), switch to “By Number of Sides” and enter how many sides your shape has; the calculator works out the interior angle and the miter cut for you.
Miter angle formula
For a regular polygon: Interior Angle = (n − 2) × 180° ÷ n
Every corner is made of two pieces meeting at an angle, so each piece only needs to be cut to half the total corner angle. A standard 90° corner needs two 45° cuts — that’s where the “45 on a miter saw” convention most people already know comes from. Saw miter gauges are usually marked from 0° at center (blade square to the fence), so the gauge setting matches the miter angle directly for a simple flat miter.
A note on compound cuts
This tool covers flat, single-plane miters — the kind you’d cut for a frame lying on a table. If your project also needs a bevel (like crown molding or an angled leg), you’re looking at a compound cut, which needs both a miter and bevel angle set together.