Crown molding calculator: how much crown molding do I need, and at what angles?
7 pieces
of 8 ft · 52 linear ft · cut flat: miter 31.6°, bevel 33.9° at a 90° corner · for a 14 × 12 ft room, 38° crown
Run your own numbers
Enter it the way you measured it: 4.5, 4 1/2,
3/8 or 10' 6".
7 pieces
of 8 ft · 52 linear ft · cut flat: miter 31.6°, bevel 33.9° at a 90° corner
A 12 by 14 ft room has 52 feet of wall to crown, 7 pieces of 8 ft molding, and cut flat on a compound miter saw a 38° crown at a 90° corner takes a 31.6° miter and a 33.9° bevel.
A worked example
A 17.5 by 11 ft room in 12 ft pieces with an 8% waste allowance, and a 52° crown at a 135° bay corner needs 6 pieces. The walls run 57 feet, 61.6 with the allowance, which is 5.1 lengths of 12 ft, so 6; at the bay corner the saw is set to an 18.1° miter and a 13.6° bevel.
What angles do I cut crown molding at?
Cut flat at a 90° corner, 38° crown takes a 31.6° miter and a 33.9° bevel, 45° crown a 35.3° miter and a 30.0° bevel, and 52° crown a 38.2° miter and a 25.8° bevel. The same settings serve inside and outside corners; what changes is which side of the blade each piece is cut on and which end keeps the long point.
How do I cut crown molding for a 45 degree corner?
A wall that turns 45°, as in a bay window, leaves a 135° corner. Type 135 as the corner angle: for 38° crown the saw goes to a 14.3° miter and a 17.6° bevel, and for 45° crown to 16.3° and 15.7°. Halving the angle is only right for crown cut upside down in the saw, where the miter alone does the work.
What else it is called
A crown molding calculator is also searched as a crown molding angle calculator, crown molding angle chart or crown molding cut calculator. 52/38 crown is the common profile: it sits 38° off the wall and 52° off the ceiling. The spring angle is printed on the label or measured with a square against the back of the molding.
Crown molding angle chart
| Corner | 38° crown: miter | bevel | 45° crown: miter | bevel | 52° crown: miter | bevel |
|---|---|---|---|---|---|---|
| 60° | 46.8° | 43.0° | 50.8° | 37.8° | 53.8° | 32.2° |
| 90° | 31.6° | 33.9° | 35.3° | 30.0° | 38.2° | 25.8° |
| 120° | 19.6° | 23.2° | 22.2° | 20.7° | 24.5° | 17.9° |
| 135° | 14.3° | 17.6° | 16.3° | 15.7° | 18.1° | 13.6° |
Saw settings for cutting crown flat on a compound miter saw. A square room corner is 90°, a 45° bay window turns 135° and a hexagon 120°. Miter = atan(sin S ÷ tan(corner ÷ 2)), bevel = asin(cos S × cos(corner ÷ 2)), with S the spring angle.
Where the numbers come from
- Pieces: the perimeter of the room, 2 × (length + width), plus the waste allowance you set, divided by the length of the pieces you buy and rounded up. The allowance starts empty because how much you lose to cuts depends on your corners and your saw.
- Angles: trigonometry of a compound miter. With S the spring angle, the angle the back of the crown makes against the wall, and the corner angle between the walls, the miter is atan(sin S ÷ tan(corner ÷ 2)) and the bevel is asin(cos S × cos(corner ÷ 2)). They match the settings carpenters print for the common case: 31.6° and 33.9° for 38° crown at a square corner, 35.3° and 30.0° for 45° crown.
The angles are for cutting the crown flat on the saw table, face up, with a compound miter saw. Cutting it upside down and nested against the fence uses the miter only, at half the corner angle, with no bevel. Walls are rarely exactly square: measure the corner with an angle finder and type what it reads.
By Javier Miralles · Last updated . How this site is made.
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