For a square corner each piece is cut at 45°, but walls, frames and trim often meet at other angles. Each piece is cut at half the joint angle, and miter saws measure from square (0°), so the saw setting is 90° minus half the corner angle. For regular polygons like hexagonal planters or octagonal frames the saw setting is 180° divided by the number of sides.
How to use the Angle Cut Calculator
- I know
- Corner angle
- Number of sides
Results update as you type, and every field accepts the units shown in its menu.
How it works
Choose whether you know the corner angle or the number of sides of a regular polygon.
Polygon miter settings
| Sides | Corner angle | Saw setting |
|---|---|---|
| 3 | 60° | 60° |
| 4 | 90° | 45° |
| 5 | 108° | 36° |
| 6 | 120° | 30° |
| 8 | 135° | 22.5° |
| 10 | 144° | 18° |
| 12 | 150° | 15° |
Tips for an accurate estimate
- Measure angles with a digital angle finder or sliding bevel, not by eye.
- Make a test cut in scrap before cutting expensive stock.
- Small angle errors add up over many joints – check the first assembly before cutting the rest.
- Keep a written list of the dimensions and angles you set on the saw or machine.
Common mistakes to avoid
- Reading the saw scale as the angle from the edge rather than from square.
- Rounding intermediate results too early.
- Mixing degrees and percent grade.
Inputs explained
| Field | What to enter |
|---|---|
| I know | Choose one: The corner angle between two pieces, The number of sides of a polygon |
| Corner angle | Units: °, rad |
| Number of sides | A number |
What each result means
- Miter saw setting = 90 – [Corner (interior) angle]÷2
- Cut angle from the board edge = [Corner (interior) angle]÷2
Formula
Corner: saw setting = 90° − corner angle ÷ 2Polygon: interior angle = 180° × (n − 2) ÷ n; saw setting = 180° ÷ nWorked example
Inputs — I know: The corner angle between two pieces; Corner angle: 90 °; Number of sides: 6.
Results — Corner (interior) angle = 90 °; Miter saw setting = 45 °; Cut angle from the board edge = 45 °.
Frequently asked questions
What angle do I cut for a hexagon?
30° on the saw (60° from the edge); each corner is 120°.
What angle for an octagon?
22.5° on the saw; each corner is 135°.
How do I measure an out-of-square corner?
Use an angle finder or bevel gauge, then halve the angle for each piece.
What formula does the Angle Cut Calculator use?
Corner: saw setting = 90° − corner angle ÷ 2.