How to use the compound miter calculator
- Measure the included wall corner rather than assuming it is exactly square.
- Identify the crown spring angle from the wall. Do not substitute the complementary ceiling angle.
- Set the calculated magnitudes using the left/right orientation for your cut as described in the saw manual.
The formula
Miter = atan(sin(spring) ÷ tan(corner ÷ 2)); bevel = asin(cos(spring) × cos(corner ÷ 2))
Worked example
A 90° corner with a 38° spring angle gives a miter of about 31.62° and bevel of 33.86° for crown molding laid flat.
Before you measure and cut
A 38° wall spring angle corresponds to a 52° ceiling angle. Entering 52° instead changes the settings.
The calculator gives magnitudes. It does not select the retained side or reverse the settings for different inside and outside corners.
Frequently asked questions
Does this apply to crown held nested?
No. Nested crown uses a different cutting setup. These equations assume the molding is laid flat.
Why test on scrap?
Real walls, molding profiles, and saw calibration vary. A test pair verifies both the angles and the orientation before using full-length stock.
Reference
DEWALT: DW716 instruction manual. Material properties and setup conventions depend on the specific product.