Miter Saw Angles Explained: Miters, Bevels & Compound Cuts
Published: September 20, 2026 • Written by Master Carpenter Jack Mercer • Fact Checked
Compound miter saws are the workhorse of the modern job site, capable of turning out hundreds of identical framing studs or slicing delicate maple casing with surgical accuracy. Yet for many woodworkers, the angle scales etched into the saw's turntable and bevel arm remain a source of confusion.
Why does a saw set to 0° cut a 90° square edge? Why does an octagon need a 22.5° cut? How do you calculate crown molding angles when corners aren't square? This guide breaks down the geometry behind every cut on your miter saw.
Miter vs Bevel: What's the Difference?
Miter Cut: An angle cut made across the width of the board by swiveling the saw table horizontally left or right. The saw blade remains strictly perpendicular (vertical) to the table surface.
Bevel Cut: An angle cut made through the thickness of the board by tilting the saw blade vertically left or right. The saw table remains locked straight at 0°.
Compound Cut: A cut that combines both movements simultaneously: the turntable is rotated to a miter angle AND the blade head is tilted to a bevel angle (essential for shadow boxes, picture frames, and flat-cut crown molding).
Why 0° on the Saw Means a 90° Cut
The most common source of confusion is the saw's graduation scale. In standard geometry, a square corner is 90 degrees. However, miter saws measure deviation from square.
- When the saw table is locked at 0°, the blade is 90° perpendicular to the fence, creating a standard square crosscut.
- When you rotate the table to 45°, the blade is cutting 45° away from perpendicular. Two 45° cuts joined together form a 90° corner (45° + 45° = 90°).
- To calculate the saw setting for any multi-sided polygon: Saw Angle = 180° − (360° ÷ Number of Sides) ÷ 2. For a 6-sided hexagon: (360 ÷ 6) = 60° corner angle; half of that is 30°. Set your saw to 30°.
Cutting Crown Molding: Nested vs Flat
Crown molding sits diagonally against both the wall and ceiling, usually with a spring angle of 38°/52° or 45°/45°. There are two distinct methods to cut it:
| Method | Setup | Advantages & Trade-Offs |
|---|---|---|
| Nested ("Upside Down & Backwards") | Rest the molding at its installed angle against the fence and table. The ceiling edge rests flat on the saw table; the wall edge rests against the fence. Set bevel to 0°; adjust miter only (usually 45°). | Fast and intuitive; eliminates complex compound math. Limited by the vertical height capacity of your saw fence. |
| Flat (Compound Cuts) | Lay the molding face up flat on the saw table. Adjust BOTH the miter angle (e.g. 31.62°) and bevel angle (e.g. 33.86°) according to crown tables. | Allows cutting massive 6" to 8" crown molding on a standard 10" or 12" sliding miter saw. Requires exact protractor readings for out-of-square corners. |
How to Calibrate Your Miter Saw for 100% Square Cuts
Factory calibration slips over time due to jobsite vibration and transport in truck beds. Follow this 5-minute calibration check:
- Unplug the saw for safety.
- Pull the saw head down and lock it in the lowered position.
- Place a precision machinist's square against the fence and against the steel body of the blade (make sure the square rests against the flat plate of the blade, NOT on the carbide teeth).
- If any daylight appears between the square and blade, loosen the fence adjustment bolts or bevel stop screws and adjust until flush.
- Perform the classic 5-cut test on a scrap scrap piece of plywood to verify that cumulative error is less than 0.005".
