{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"crown-molding-miter"},"result":{"entity_type":"calculator","id":"crown-molding-miter","calculator_id":"crown-molding-miter","canonical_url":"https://tttkmbb.com/construction/crown-molding-miter","name":"Crown Molding Miter Calculator","title":"Crown Molding Miter Calculator – Compound Miter and Bevel Angles from Corner Angle and Spring Angle","category":"construction","category_name":"Construction & Home","tool_name":"calculate_crown_molding_angles","featured_mcp_tool":false,"description":"Computes the saw settings for cutting crown molding flat on a compound miter saw from the wall corner angle and the molding's spring angle: miter = atan(sin(spring) / tan(corner/2)) and bevel = asin(cos(spring) × cos(corner/2)), plus the miter setting for cutting the molding nested (upside-down against the fence) and which end of each piece to keep.","use_when":"You need miter and bevel settings for inside or outside crown molding corners, including non-square corners such as 135° bay-window walls.","do_not_use_when":"The trim is flat stock such as baseboard or casing, where the miter is simply half the corner angle (45° for a square corner; use baseboard-trim for quantities), or you need general angle trigonometry (use trigonometry).","inputs":[{"name":"corner_angle_degrees","label":"Corner angle","type":"number","unit":"°","required":false,"default":90,"min":60,"max":180,"description":"Angle between the two walls measured inside the room with an angle finder: 90 for a square corner, 135 for a typical bay-window corner. Drywall corners are rarely exactly 90°.","example":90},{"name":"spring_angle_degrees","label":"Spring angle","type":"number","unit":"°","required":false,"default":38,"min":0,"max":90,"description":"Angle between the back of the molding and the wall when installed: 38 for the common 52/38 profile, 45 for 45/45 crown, 52 for 38/52 crown (the number printed on the profile is sometimes the ceiling angle, so check with a square).","example":38},{"name":"corner_type","label":"Corner type","type":"enum","required":false,"default":"inside","values":[{"value":"inside","label":"Inside corner","aliases":["internal","in"]},{"value":"outside","label":"Outside corner","aliases":["external","out"]}],"description":"Inside (concave) or outside (convex) corner; the angles are identical, only the fence side and the end to keep differ.","example":"inside"}],"outputs":[{"name":"miter_angle_degrees","label":"Miter angle (flat)","type":"number","unit":"°","decimals":2,"description":"Saw-table (miter) setting for the molding lying flat: atan(sin(spring) / tan(corner/2))."},{"name":"bevel_angle_degrees","label":"Bevel angle (flat)","type":"number","unit":"°","decimals":2,"description":"Blade-tilt (bevel) setting for the molding lying flat: asin(cos(spring) × cos(corner/2))."},{"name":"nested_cut_angle_degrees","label":"Nested miter angle","type":"number","unit":"°","decimals":2,"description":"Miter setting with the bevel at 0° when the molding is cut upside-down and nested against the fence at its spring angle: 90° − corner/2."},{"name":"ceiling_angle_degrees","label":"Ceiling angle","type":"number","unit":"°","decimals":2,"description":"90° − spring angle: the angle between the molding and the ceiling."},{"name":"cutting_instructions","label":"Cutting instructions","type":"string","decimals":4,"description":"Fence side, miter direction and which side of the blade to keep for the left and right pieces (left-tilting single-bevel saw)."}],"input_schema":{"type":"object","properties":{"corner_angle_degrees":{"description":"Angle between the two walls measured inside the room with an angle finder: 90 for a square corner, 135 for a typical bay-window corner. Drywall corners are rarely exactly 90°. Unit: °.","type":"number","minimum":60,"maximum":180,"default":90,"examples":[90],"x-unit":"°"},"spring_angle_degrees":{"description":"Angle between the back of the molding and the wall when installed: 38 for the common 52/38 profile, 45 for 45/45 crown, 52 for 38/52 crown (the number printed on the profile is sometimes the ceiling angle, so check with a square). Unit: °.","type":"number","minimum":0,"maximum":90,"default":38,"examples":[38],"x-unit":"°"},"corner_type":{"description":"Inside (concave) or outside (convex) corner; the angles are identical, only the fence side and the end to keep differ.","type":"string","enum":["inside","outside"],"default":"inside","examples":["inside"]}},"additionalProperties":false},"output_schema":{"type":"object","properties":{"miter_angle_degrees":{"description":"Saw-table (miter) setting for the molding lying flat: atan(sin(spring) / tan(corner/2)). Unit: °.","type":"number","x-unit":"°"},"bevel_angle_degrees":{"description":"Blade-tilt (bevel) setting for the molding lying flat: asin(cos(spring) × cos(corner/2)). Unit: °.","type":"number","x-unit":"°"},"nested_cut_angle_degrees":{"description":"Miter setting with the bevel at 0° when the molding is cut upside-down and nested against the fence at its spring angle: 90° − corner/2. Unit: °.","type":"number","x-unit":"°"},"ceiling_angle_degrees":{"description":"90° − spring angle: the angle between the molding and the ceiling. Unit: °.","type":"number","x-unit":"°"},"cutting_instructions":{"description":"Fence side, miter direction and which side of the blade to keep for the left and right pieces (left-tilting single-bevel saw).","type":"string"}}},"formula":"miter = atan(sin(spring_angle) / tan(corner_angle/2)); bevel = asin(cos(spring_angle) × cos(corner_angle/2)); nested miter = 90° − corner_angle/2 (bevel 0°); ceiling angle = 90° − spring_angle.","method":"Standard compound-miter formulas for a molding lying flat on the saw table; for a 90° corner and a 38° spring angle they give the familiar 31.62° miter and 33.86° bevel, and 35.26° / 30.00° for 45° crown. The corner-piece instructions follow the usual saw-manual chart for a left-tilting saw; cut and test a short offcut pair before cutting to length.","sources":[{"name":"Wikipedia – Crown molding","url":"https://en.wikipedia.org/wiki/Crown_molding","type":"reference","retrieved_at":"2026-09-24"},{"name":"Wikipedia – Miter saw (compound miter saws)","url":"https://en.wikipedia.org/wiki/Miter_saw","type":"reference","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"90° inside corner, 52/38 crown (38° spring)","inputs":{"corner_angle_degrees":90,"spring_angle_degrees":38,"corner_type":"inside"},"expected":{"miter_angle_degrees":31.62,"bevel_angle_degrees":33.86,"nested_cut_angle_degrees":45,"ceiling_angle_degrees":52},"url":"https://tttkmbb.com/api/v1/calculate/crown-molding-miter?corner_angle_degrees=90&spring_angle_degrees=38&corner_type=inside"},{"name":"135° outside corner (bay window), 45° crown","inputs":{"corner_angle_degrees":135,"spring_angle_degrees":45,"corner_type":"outside"},"expected":{"miter_angle_degrees":16.32,"bevel_angle_degrees":15.7,"nested_cut_angle_degrees":22.5},"url":"https://tttkmbb.com/api/v1/calculate/crown-molding-miter?corner_angle_degrees=135&spring_angle_degrees=45&corner_type=outside"}],"faq":[{"q":"Which is the spring angle on 52/38 crown?","a":"The angle between the molding's back and the wall, 38° for the common 52/38 profile (52° is the angle to the ceiling). Hold the piece against a framing square: the wall-side angle is the spring angle."},{"q":"Flat or nested: which method should I use?","a":"Nested (upside-down, at the spring angle against the fence) needs only a miter setting of 90° − corner/2 but requires the molding to fit under the fence; wide crown is cut flat with the compound settings given here."},{"q":"My saw tilts right, not left.","a":"Swap left and right in the instructions (mirror the fence side and the piece to keep); the miter and bevel values are unchanged."}],"tags":["crown molding calculator","crown molding angles","compound miter","bevel angle","miter saw settings","52/38 crown"],"related":[{"calculator_id":"baseboard-trim","reason":"Quantity of baseboard or flat trim for the same room."},{"calculator_id":"trigonometry","reason":"Evaluate the sine, cosine and tangent used by the formulas."},{"calculator_id":"angle","reason":"Convert between degrees and radians."}],"links":{"html":"https://tttkmbb.com/construction/crown-molding-miter","markdown":"https://tttkmbb.com/construction/crown-molding-miter.md","json":"https://tttkmbb.com/construction/crown-molding-miter.json","api":"https://tttkmbb.com/api/v1/calculate/crown-molding-miter","schema":"https://tttkmbb.com/api/v1/calculators/crown-molding-miter","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T03:49:15Z","next_actions":[{"tool":"run_calculator","calculator_id":"crown-molding-miter","reason":"Run Crown Molding Miter Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/construction/crown-molding-miter.md"}}