Get the miter and bevel settings for cutting crown molding flat or nested, a cut chart for inside and outside corners, and how many pieces to buy. Enter your crown's spring angle, the wall corner angle and your room's walls.
Last updated:
Molding and corners
°
Angle between the back of the crown and the wall.
°
90 for square corners, 135 for bay windows; 270 = outside square corner.
in
Optional: for the layout line on the wall.
Room and material
Room shape
ft
ft
One number per wall run that gets crown, in feet (use decimals: 10.5 = 10 ft 6 in).
%
10% for simple rooms, 15–20% with many corners.
$
Enter your values to see the result.
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How to use the Crown Molding Calculator
Choose the spring angle of your crown (52/38 is the most common).
Enter the wall corner angle: 90° for square corners, 135° for a bay.
Enter the room as length × width, or list every wall and count the corners.
Pick the stock length and waste, and optionally the price per foot.
Use the cut chart at the saw and test-cut a corner on scrap first.
Crown molding formulas
Flat miter = atan(sin S ÷ tan(W ÷ 2))
Flat bevel = asin(cos S × cos(W ÷ 2))
Nested miter = 90° − W ÷ 2, bevel 0°
S = spring angle (back of crown to wall), W = wall corner angle. An outside corner of 270° uses the same numbers as 90°.
Linear feet = sum of walls × (1 + waste); pieces = linear feet ÷ stock length, rounded up.
Layout line = crown width × cos S below the ceiling; projection = width × sin S.
Saw settings for common crown and corners (crown flat)
Wall corner
52/38 crown: miter / bevel
45/45 crown: miter / bevel
Nested miter
90°
31.6° / 33.9°
35.3° / 30.0°
45°
120°
19.6° / 23.2°
22.2° / 20.7°
30°
135°
14.3° / 17.6°
16.3° / 15.7°
22.5°
150°
9.4° / 11.8°
10.7° / 10.5°
15°
Tips for installing crown
Measure each corner with an angle finder; drywall corners are rarely exactly 90°. Small differences change the cut noticeably.
Snap a layout line at the crown's drop below the ceiling so every piece sits at the same angle.
Join long walls with a 45° scarf joint over a stud rather than a square butt joint, and glue the scarf.
Install the longest wall first with square-cut ends into the corners, and cope the pieces that meet it.
Paint-grade crown can be caulked; for stain-grade crown, buy a little extra for perfect grain matches.
Frequently asked questions
What angle do I cut crown molding at?
For crown laid flat on a compound miter saw, miter = atan(sin S ÷ tan(W/2)) and bevel = asin(cos S × cos(W/2)), where S is the spring angle and W the wall corner. For common 52/38 crown at a 90° corner that is a 31.6° miter and 33.9° bevel; for 45/45 crown it is 35.3° and 30°. Cut nested (upside down) the setting is simply a 45° miter with no bevel.
What is the spring angle of crown molding?
It is the angle between the back of the molding and the wall when installed. 52/38 crown sits at 38° from the wall and 52° from the ceiling; 45/45 crown sits at 45° to both. Check it by holding the crown in a framing square: the flat back edges touch both legs.
How much crown molding do I need?
Measure each wall that gets crown, add them up and add 10–15% for waste and corner cuts, then divide by the stock length and round up. A 12 × 14 ft room has a 52 ft perimeter; with 15% waste that is 59.8 ft, or five 12 ft pieces.
What is the difference between cutting crown flat and nested?
Flat, the crown lies face up on the saw table and needs both a miter and a bevel (a compound cut). Nested, the crown is placed upside down with its flats against the table and fence, as if the table were the ceiling, so only a miter is needed. Nested cuts need a saw tall enough to hold the crown.
Should I miter or cope inside corners?
Most carpenters cope inside corners: cut the first piece square into the corner, miter the second, then remove the back along the profile with a coping saw. A coped joint stays tight even if the corner is not exactly 90°. Outside corners are always mitered.
How do I cut crown for a 135° bay window corner?
Use the corner angle in the formulas. For 52/38 crown at 135°, the flat settings are about a 14.3° miter and 17.6° bevel; nested, the miter is 22.5°. The calculator shows the settings and a table for other corners.
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