Crown Molding Miter & Bevel Calculator
Enter the measured corner and the molding’s spring angle to get the compound miter settings for a flat cut, the simple miter for a nested cut, and a saw-limit check.
Flat-cut miter setting (°)31.62
- Flat-cut bevel setting (°)
- 33.86
- Nested-cut miter setting (°)
- 45
- Nested-cut bevel setting (°)
- 0
- Complementary spring angle (°)
- 52
- Saw compatibility
- Flat-cut is compatible; nested-cut is compatible with this saw.
- Test-cut setup
- Make a mirrored scrap pair for the inside corner; retain the calculated magnitudes and reverse the saw direction for the matching piece.
Settings are magnitudes only; use the saw manual for left-versus-right miter, bevel direction, and molding orientation.
Nested cutting also requires enough fence and blade capacity for the molding profile.
How to use this calculator
- Measure the included angle between walls for an inside corner, or the smaller direction-change angle for an outside corner.
- Enter the crown profile’s spring angle measured from the ceiling plane, not its complementary wall angle.
- Enter the largest miter and bevel settings your saw can reach.
- Use the flat-cut settings when the molding lies on the saw table, or the nested miter when it is held at its installed angle against the fence.
- Make the mirrored scrap test joint described in the result before cutting finished molding.
How crown molding miter and bevel settings are calculated
Crown molding meets both the wall and ceiling, so a flat cut on a compound miter saw needs two settings. Measure the corner angle rather than assuming the walls are square, then use the molding’s installed spring angle. This calculator treats that spring angle as the angle from the ceiling plane. A profile marked 38°/52° has a 38° ceiling-plane spring angle and a 52° complementary wall-plane angle; those labels describe the same profile from different reference planes, not two interchangeable inputs.
Let A be the measured corner angle, S the ceiling-plane spring angle, and H equal A ÷ 2. For crown laid flat on the saw table, the setting magnitudes are Mflat = atan(sin(S) ÷ tan(H)) and Bflat = asin(cos(S) × cos(H)), with all trigonometric values calculated in degrees. The calculator clamps the input to the inverse sine to the valid range from −1 to 1 so a floating-point rounding artifact cannot produce an invalid result.
For crown held nested against the fence at its installed spring angle, the blade stays upright. The miter magnitude is Mnested = (180° − A) ÷ 2 and the bevel is 0°. The nested method is mechanically simpler, but the molding must sit firmly at its intended angle and fit within the saw’s fence and blade capacity.
What changes the settings most
The corner angle changes both methods. A corner that opens beyond 90° lowers the required miter, while a tighter corner raises it. The spring angle affects only the flat-cut compound settings: at a 90° corner, 38° crown uses about 31.62° miter and 33.86° bevel, while 45° crown uses about 35.26° miter and 30.00° bevel. The calculator also compares each required magnitude with your saw limits, so a setting beyond the scale is shown as unavailable instead of being rounded into a plausible but unusable answer.
Inside corners, outside corners, and test cuts
For the same measured angle and profile, inside and outside corners use the same setting magnitudes. What changes is which piece is left or right, which end is retained, the saw direction, and the molding orientation. Those details vary by saw and whether the crown is cut flat or nested, so use the saw manual for its direction chart. Cut a mirrored scrap pair and hold it in the actual corner before committing finished stock.
What this calculator leaves out
This calculation assumes identical crown profiles and a symmetric joint. It does not account for walls or ceilings that are bowed, a changing spring angle, irregular molding backs, blade kerf, coping technique, fence interference, or the saw’s particular direction markings. A coped inside corner still benefits from a well-fitted mating profile, but the coping operation itself is not calculated here.
Worked example
For a 90° inside corner with 38° crown, the half corner is 45°. The flat miter is atan(sin(38°) ÷ tan(45°)) = 31.62°, and the bevel is asin(cos(38°) × cos(45°)) = 33.86°. The nested setting is (180° − 90°) ÷ 2 = 45° miter with a 0° bevel.
With a saw limited to 50° miter and 45° bevel, both methods are available. The complementary value is 52°, which explains why this same profile may be labeled 38°/52°. For an outside corner, retain those magnitudes but make the mirrored scrap pair as an outside joint and follow the saw’s direction chart.
Common questions
What are the miter and bevel settings for 38° crown molding?
For a 90° corner, 38° crown cut flat uses about 31.62° miter and 33.86° bevel. If the molding is held nested against the fence at its installed angle, it uses a 45° miter and no bevel. Different corner angles require different settings.
How do I measure an out-of-square wall corner?
Use an angle finder or bevel gauge at the height where the crown will sit, then enter the included angle for an inside corner. For an outside corner, enter the smaller direction-change angle specified by the tool. Check more than one spot when the walls are visibly irregular.
Is crown molding spring angle measured from the wall or ceiling?
This calculator uses the spring angle measured from the ceiling plane. A common profile is marked 38°/52° because its angle from the ceiling is 38° and its complementary angle from the wall is 52°. Enter 38°, not 52°, for that profile.
What is the difference between cutting crown flat and nested?
Flat cutting places the crown on the saw table and requires a compound miter and bevel. Nested cutting holds the crown against the fence in its installed orientation, so the blade stays vertical and only the miter changes. Nested cutting can be faster but needs enough physical clearance for the molding.
Do inside and outside corners use different angle magnitudes?
Not when the measured angle and crown profile are the same. The miter and bevel magnitudes match, but the saw direction, molding orientation, retained end, and mirrored pairing change. Follow your saw manual and verify the direction on scrap.
Should I cope an inside corner instead of mitering it?
Coping can hide small changes in wall angle and seasonal movement better than a two-piece mitered inside joint. It still starts with a correctly cut mating profile, then removes material behind that profile. This calculator provides the angle setup but does not create a coping template.