| Crown & corner | Flat miter | Flat bevel | Nested miter |
|---|---|---|---|
| 52/38, 90° inside/outside | 31.6° | 33.9° | 45° |
| 45/45, 90° inside/outside | 35.3° | 30.0° | 45° |
| 52/38, 135° corner (octagon) | 14.3° | 17.6° | 22.5° |
| 45/45, 135° corner (octagon) | 16.3° | 15.7° | 22.5° |
Perimeter = 2 × (length + width) for a rectangular room, plus 10–15% for miters and error, divided by your stock length and rounded up. Crown runs over doors and windows, so nothing is subtracted for openings.
Nested against the fence: a plain 45° miter. Cut flat: a compound 31.6° miter and 33.9° bevel for 52/38 crown, or 35.3° and 30° for 45/45.
How far the crown tips off the wall. Standard crown is 52/38 (52° to the wall, 38° to the ceiling); the other common profile is 45/45. It sets both compound angles, so identify it first.
10–15% over the measured perimeter. Crown wastes more than baseboard because every corner is a miter and coped joints lose a few inches per cut.
Most rooms are all inside corners (often coped for a tight fit); outside corners wrap projections and are mitered. Same-angle corners use the same saw settings. Only the waste side changes.