Miter and Crown Molding Angle Calculator
Type a corner angle in degrees, and a crown spring angle from the molding's package, and get the miter angle for flat trim, the miter and bevel for crown molding laid flat on the saw, and the cut for a regular polygon; the corners choice counts the cuts for a frame.
Estimates for planning, not professional advice. Read the full notice.
Example: a square frame and an eight-sided one
8 miter cuts
- Flat trim, each piece cut at 45 degrees
- Crown on the flat, miter angle 31.62 degrees
- Crown on the flat, bevel angle 33.86 degrees
- Regular polygon, corner 135 degrees
- Regular polygon, each piece cut at 22.5 degrees
Estimate for planning, from what you entered and the product data shown. Check product labels and your supplier before you buy.
Your project
Enter a size to see your total.
Each product is rounded up once for the whole project, so the total can be less than the items bought alone added together. A line counted from a cut layout (sheets, boards or tiles laid out piece by piece) is counted for each item and added.
Saw settings
Type your angles in degrees. A box left empty is skipped.
The angle between the two walls, measured inside the corner.
The angle of the crown's back against the wall, from the molding's package.
A whole number of sides, from three.
Shopping list
| Item | Size | Buy |
|---|---|---|
| Miter cuts to make | miter cuts | 8 |
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Worked example: a square frame and an eight-sided one
Show the working
- What is left of a straight line at the corner 180 degrees − 90 degrees = 90 degrees
- Each flat piece is cut at half of that 90 degrees ÷ 2 = 45 degrees
- Cuts: two for each corner 4 corners × 2 cuts = 8 miter cuts
- A regular polygon's corner: the sides less two, over the sides, times a straight line 6 sides less two ÷ 8 sides × 180 degrees = 135 degrees
Assumptions
The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.
| Assumption | Value | Details and changes |
|---|
Feet and inches, like 12' 6"
Saw settings by corner angle
Flat trim miter and crown-on-the-flat miter and bevel for corners from eighty to one hundred fifty degrees, at two spring angles
| Corner | Flat trim | Crown 38: miter | Crown 38: bevel | Crown 45: miter | Crown 45: bevel |
|---|---|---|---|---|---|
| 80 degrees | 50 degrees | 36.27 degrees | 37.13 degrees | 40.12 degrees | 32.8 degrees |
| 90 degrees | 45 degrees | 31.62 degrees | 33.86 degrees | 35.26 degrees | 30 degrees |
| 100 degrees | 40 degrees | 27.32 degrees | 30.43 degrees | 30.68 degrees | 27.03 degrees |
| 110 degrees | 35 degrees | 23.32 degrees | 26.87 degrees | 26.34 degrees | 23.93 degrees |
| 120 degrees | 30 degrees | 19.57 degrees | 23.2 degrees | 22.21 degrees | 20.7 degrees |
| 130 degrees | 25 degrees | 16.02 degrees | 19.45 degrees | 18.25 degrees | 17.39 degrees |
| 140 degrees | 20 degrees | 12.63 degrees | 15.64 degrees | 14.43 degrees | 14 degrees |
| 150 degrees | 15 degrees | 9.37 degrees | 11.77 degrees | 10.73 degrees | 10.55 degrees |
The two spring angles are examples; yours is on the molding's package. Crown settings are for crown laid flat on the saw table.
Questions
How do I find the miter angle for a corner?
Measure the angle between the two walls, take it from a straight line and halve what is left. A square corner gives a flat trim miter of half a right angle. The first box above does this for any corner you type.
What is the spring angle of crown molding?
It is the angle between the back of the crown and the wall. It is printed on the package, and the calculator uses the number you type rather than assuming one.
What does 52/38 mean on crown molding?
The two numbers are the two angles of the molding's back against the ceiling and the wall, which together make a right angle. The spring angle is the one against the wall, so type that one.
How do I cut a compound miter on crown?
Lay the crown flat on the saw table, set the miter and the bevel the calculator gives for your corner and spring angle, and cut one piece for each side of the corner. The table lists settings for common corners.