Dial in accurate compound cuts for crown molding. Enter the wall corner angle and the molding spring angle to compute the miter and bevel settings for a compound miter saw. Optional molding width lets you estimate the cut-face length for layout checks and test cuts.
miter = arctan(sin(S)/tan(C/2)) and
bevel = arcsin(cos(S) x cos(C/2)), where C is the corner angle and S is the spring angle.
Flat mode lays the crown on the saw table and uses the compound miter and bevel settings. Nested mode holds the crown upside down at its installed spring angle with the ceiling edge on the table, the wall edge against the fence, and bevel set to 0 degrees.
| Piece | Miter swing | Bevel tilt | Long point / keep edge |
|---|---|---|---|
| Enter angles to calculate saw instructions. | |||
Make mirrored test pieces from scrap before cutting full-length molding. Saw labels vary, so match left/right to your saw's handle and fence orientation.
Crown molding sits at an angle between the wall and ceiling, so its profile is neither flat nor vertical. The spring angle is the angle between the back of the molding and the wall or ceiling. A 38 degree spring angle is common for traditional profiles, while 45 and 52 degree spring angles are also standard. The corner angle is the angle between the two walls you are joining. A typical interior corner is 90 degrees, but real rooms are often out of square and can be 88 to 94 degrees or more. This calculator solves the compound cut that blends those two geometric realities.
When crown is cut flat on a miter saw, the tool needs two settings: the miter (rotation in the horizontal plane) and the bevel (tilt of the blade). The miter controls how the piece swings around the corner, while the bevel compensates for the spring angle so the molding returns to the correct wall and ceiling surfaces after the cut. Because the molding is installed at a spring angle, the effective corner angle seen by the saw is not simply half of the room corner. Trigonometry projects the spring angle onto the miter and bevel planes, producing angles that are not intuitive but are repeatable.
The optional molding width is included for layout checks. While the width does not change the miter or bevel, it changes the length of the cut face across the molding. Knowing that length helps you mark the long point, verify the saw fence setup, and plan for complex returns. For precision building and finish carpentry, this extra check can save material and reduce cumulative error over long runs.
For nested cuts, hold the crown upside down at the same spring angle it will have on the wall. The saw bevel stays at 0 degrees and the miter becomes a half-corner workflow. This is faster with crown stops, but it only works if the molding is supported at the correct spring angle against the fence.
Let C be the wall corner angle and S be the spring angle (degrees). Convert to
radians for trigonometry. The compound angles are:
miter = arctan( sin(S) / tan(C/2) )
bevel = arcsin( cos(S) x cos(C/2) )
Optional cut-face length for molding width W: face = W / cos(miter).
These flat-on-saw compound settings use the same formula as the calculator. The nested miter column is half of the wall corner with bevel at 0 degrees.
| Spring angle | Wall corner | Flat miter | Flat bevel | Nested miter |
|---|---|---|---|---|
| 38 deg | 85 deg | 33.90 deg | 35.52 deg | 42.50 deg |
| 38 deg | 88 deg | 32.52 deg | 34.53 deg | 44.00 deg |
| 38 deg | 90 deg | 31.62 deg | 33.86 deg | 45.00 deg |
| 38 deg | 92 deg | 30.73 deg | 33.19 deg | 46.00 deg |
| 38 deg | 95 deg | 29.43 deg | 32.17 deg | 47.50 deg |
| 45 deg | 85 deg | 37.66 deg | 31.42 deg | 42.50 deg |
| 45 deg | 88 deg | 36.21 deg | 30.57 deg | 44.00 deg |
| 45 deg | 90 deg | 35.26 deg | 30.00 deg | 45.00 deg |
| 45 deg | 92 deg | 34.33 deg | 29.42 deg | 46.00 deg |
| 45 deg | 95 deg | 32.94 deg | 28.54 deg | 47.50 deg |
| 52 deg | 85 deg | 40.69 deg | 27.00 deg | 42.50 deg |
| 52 deg | 88 deg | 39.21 deg | 26.29 deg | 44.00 deg |
| 52 deg | 90 deg | 38.24 deg | 25.81 deg | 45.00 deg |
| 52 deg | 92 deg | 37.27 deg | 25.32 deg | 46.00 deg |
| 52 deg | 95 deg | 35.83 deg | 24.58 deg | 47.50 deg |
Most miter saws mark 0 degrees as a square crosscut, then swing left or right to the requested miter. Some saws emphasize detents at 22.5, 31.6, and 45 degrees, so a calculated 31.62 degree setting may be shown as the 31.6 crown detent. Bevel scales also start at 0 degrees with the blade vertical, but the tilt direction changes by piece. The output table separates the numeric setting from left/right direction so you can match your saw scale without changing the underlying calculation.
Use the rounding control for the setting you can actually make: nearest 0.1 degree for digital saws, nearest 0.5 degree for basic scales, or nearest common detent for fast field setup. If a fit changes after rounding, make the correction on test pieces before cutting the finished run.
Inputs: 90 degree wall corner, 38 degree spring angle, flat mode.
Settings: 31.62 degree miter, 33.86 degree bevel.
Direction: Cut inside left and inside right as mirrored pieces, then test fit both short blocks before production cuts.
Inputs: 88 degree wall corner, 38 degree spring angle, flat mode.
Settings: 32.52 degree miter, 34.53 degree bevel.
Direction: The miter is slightly steeper than the 90 degree benchmark. Recheck the angle finder reading if the back closes before the face.
Inputs: 92 degree wall corner, 38 degree spring angle, flat mode.
Settings: 30.73 degree miter, 33.19 degree bevel.
Direction: Use the outside left/outside right rows and watch the long point, because outside corners expose wrong-end cuts immediately.
Inputs: 90 degree wall corner, 45 degree spring angle, flat mode.
Settings: 35.26 degree miter, 30.00 degree bevel.
Direction: Do not use a 38/52 saw chart for 45/45 crown; the bevel differs enough to leave a visible ceiling or wall gap.
| Bad-fit result | What to recheck |
|---|---|
| Gap at the ceiling | Recheck the spring angle and bevel direction. The crown may not be held at the same angle used for the calculation. |
| Gap at the wall | Confirm the spring angle and that the wall edge was against the correct reference face in nested mode. |
| Outside corner open at the front | Re-measure the outside wall angle and confirm the miter was swung to the outside-corner row, not the inside row. |
| Inside corner tight at the back | The wall angle may be smaller than assumed, or the miter direction may be mirrored incorrectly. |
| Wrong long point | Check whether you cut the left or right piece, and mark top edge, bottom edge, wall side, and ceiling side before cutting. |
| Repeated mismatch on both pieces | Verify the crown profile is really 38/52, 45/45, or the custom spring angle entered in the calculator. |
The spring angle is the molding profile angle against the wall or ceiling. The corner angle is the angle between the walls you are joining.
Because the molding is installed at an angle, the saw has to project that angle into the miter and bevel planes.
Lay the crown flat on the saw table, enter the measured wall and spring angles, then set both the miter and bevel shown by flat mode. Use the orientation rows for left/right direction.
Hold the crown upside down against the fence at the installed spring angle. Keep the blade bevel at 0 degrees and set the saw miter to half of the measured corner angle.
Yes. Select nested mode for the bevel-0 workflow. Use flat mode only when the crown is lying flat on the saw table.
Coped inside corners are often more forgiving because one piece is square cut and the other follows the profile. Mitered inside corners can still work when the room angle and spring angle are measured accurately.
It describes the complementary angles on the back of the crown profile. If the profile sits 38 degrees off one surface, the other back angle is about 52 degrees.
Use a digital angle finder, bevel gauge, or two overlapping straight scraps to transfer the included angle. Enter the full wall angle, such as 88 or 92 degrees, not half the angle.
Use the same numeric settings but follow the outside left and outside right orientation rows. The long point moves to the outside face.
Charts may assume a different spring angle, a nested setup, rounded detents, or a different convention for labeling left and right saw movement.
Yes. Real-world spring angles vary by manufacturer, and walls are rarely perfect.
This tool applies standard compound miter trigonometry for flat cuts and a half-corner bevel-0 workflow for nested cuts. It outputs saw settings, direction notes, and long-point reminders that match your selected method. All calculations run client-side for privacy.
Most profiles fall into 38, 45, or 52 degrees, which is why saw tables often list those presets.
Even small framing errors can change the ideal miter by a degree or two.
Some carpenters cut crown nested against the fence to avoid bevel adjustments.
Wider molding changes the cut-face length, which affects layout and scarf joints.
Accurate miter and bevel settings reduce caulk and give tighter inside corners.
Results are for planning and layout. Always follow tool safety practices and verify angles with test cuts before production work.