Crown Molding Calculator

Spring Angle and Compound Miters

Crown sits on a spring angle—the angle between the back of the molding and the wall—so a simple 45° miter on the saw table does not equal a 45° corner on the ceiling. When you lay crown flat, the saw needs both a miter (turn) and a bevel (tilt) that depend on the corner and the spring. Nested cutting stands the crown as it will hang (often upside down against the fence) so you can cut a single miter with the blade square, which many finish carpenters prefer once the stops are set.

How to use this calculator

1. Measure the actual corner with a protractor or digital angle finder—do not assume every room is 90°.
2. Select the molding’s spring angle (38°, 45°, or 52° are the usual catalog values).
3. Choose flat or nested method and set your miter saw to the displayed angles; test on scrap first.

Walls out of square

Enter the measured inside or outside corner, not the “ideal” plan angle. A 92° inside corner needs different settings than 90°, and coping the inside joint still benefits from a correct first cut on the square piece. Outside corners that wrap a column or bulkhead should be dry-fitted before glue or nails; paint-grade work can hide a slight gap with caulk, but stained hardwood needs the compound to land clean.

FAQ