Angle Cut Calculator (Miter Angles)
To join two boards at a corner, each piece is cut at half the corner angle. Enter the angle of the corner you're framing — measure it with an angle finder, since walls are rarely a perfect 90° — and the calculator returns the miter for each piece and the setting to dial into a miter saw.
Your measurements
The total angle the two boards form. 90° is a square corner.
The cut
- Corner angle
- 90°
- Joint type
- Square corner
Miter angle per piece
45°
Saw setting 45° (90° − miter)
Estimates only. Verify against your supplier's coverage figures before ordering.
The formula
Miter per piece = Corner angle ÷ 2 · Miter-saw setting = 90° − miter
Example: A square 90° corner: each piece is cut at 45° (90 ÷ 2), and the miter saw is set to 45° (90 − 45).
How it works
- 1Two boards meeting at a corner split the angle evenly, so each is mitered at half the corner angle.
- 2Miter angle per piece = corner angle ÷ 2.
- 3A miter saw reads 0° as a straight (square) cut, so its setting is 90° − the miter angle. The two numbers match only at a 45° miter.
- 4For a regular polygon, the corner angle is (sides − 2) × 180 ÷ sides — a hexagon is 120°, an octagon 135°.
Frequently asked questions
What angle do I cut for a 90-degree corner?
Each piece is cut at 45° (90 ÷ 2), which is also the 45° setting on a standard miter saw. The two 45° cuts meet to form the square corner.
How do I cut a corner that isn't 90 degrees?
Measure the actual corner angle with an angle finder, then cut each piece at half of it. A 120° corner needs two 60° miters; a 100° corner needs two 50° miters.
What's the difference between the miter angle and the saw setting?
The miter angle is the angle of the cut relative to the board's edge. A miter saw measures from a square cut (0°), so you set it to 90° minus the miter angle. They're equal only at 45°.