Toolnido

Crown Molding Angle Calculator: Miter and Bevel for Inside and Outside Corners

Enter the wall corner angle and the spring angle of your crown molding to get miter and bevel saw settings for left and right pieces of inside and outside corners. Runs in your browser.

Saw-setting estimate only, in degrees. Real walls are rarely exactly square and saw scales vary: always test the cut on scrap molding first. Values marked UNSOURCED are common figures that nobody has confirmed here: check them on your own molding and saw.

Corner and molding

45 to 179. Inside corner: the angle between the walls, measured in the room. Outside corner: the angle of the solid corner (90 for a square one). Measure it with an angle finder or sliding bevel.

Angle between the back of the molding and the wall. Verify it on the molding you have.

How you will cut

The 0.1 values are always shown. Rounding only adds a note with how far off a rounded setting would be.

When to use this

  • You are cutting crown molding on a compound miter saw and want the miter and bevel for a corner that is not a standard 90 degrees.
  • You want to know which end of the board to cut and which side of the blade to keep for an inside or outside corner.
  • You cut crown nested upside down against the fence and want the miter angle for your corner.

How to use

  1. Measure the wall corner with an angle finder or a sliding bevel and type it in. Use 90 if you have checked that the corner is square.
  2. Choose the spring angle of your molding: 38 for the usual 52/38 crown, 45, 52 or a custom value you measured.
  3. Pick how you will cut: flat on the saw table (miter and bevel) or nested against the fence (miter only).
  4. Press Calculate saw settings and read the row for your corner and piece. Test on scrap molding before cutting good stock.

Examples

Understanding the result

With the molding flat on the table, back down and the ceiling edge against the fence, the blade goes through the middle of the corner. With spring angle S and corner angle C, miter = atan( sin S / tan(C/2) ) and bevel = asin( cos S x cos(C/2) ). Cut nested upside down against the fence, the blade stays vertical and the miter is 90 minus half the corner angle. An inside and an outside corner of the same measured angle use the same two numbers; the swing directions and the side of the blade you keep are mirrored. Left and right are from where you stand in front of the saw: miter left means the handle swings left, bevel left means the blade top leans left.

Assumptions this tool makes

Limitations

FAQ

What is the miter and bevel for crown molding at a 90 degree corner?

For a 38 degree spring angle, cut flat, the miter is 31.6 degrees and the bevel is 33.9 degrees. For a 45 degree spring angle they are 35.3 and 30.0 degrees.

What is spring angle?

It is the angle between the back of the molding and the wall when the molding is installed. Hold the molding in place against a square corner and measure the angle between its back and the wall with a bevel gauge. Profiles labelled 52/38 are normally 38 degrees from the wall.

What if my walls are not square?

Measure the corner angle and type it in. The tool splits the angle in half for you. Because real corners drift, always test on scrap and adjust by a degree or less until the joint closes.

Should I cope or miter crown molding?

Inside corners are often coped because a coped joint hides small gaps when walls are out of square or the wood moves. Outside corners must be mitered. This tool only calculates miter settings.

Why do inside and outside corners have the same angles?

The geometry of the cut only depends on the corner angle. What changes is which way the saw swings and tilts and which side of the blade you keep.

Is my input sent anywhere?

No. Everything is calculated in your browser.

Related tools

More in General Tools