Woodworking & Construction Calculators

Fine woodworking & cabinetry

Crown Molding Miter and Bevel Calculator

Spring is the angle between the wall and the back of the crown: 38° for the common 52/38 crown, 45° for 45/45 crown. Wall angle is 90° for a square inside corner. The angles are for crown cut lying flat on the saw table.

Inputs

Units
°

Results

Miter (table)
31.62°
Bevel (blade tilt)
33.86°

The Result is indicative and educational. It does not constitute a design, a technical opinion or medical advice and does not replace calculations or verification by a person with the appropriate qualifications and authorisations. Before purchase, installation or use in practice – in particular in electrical installations – the Result should be verified by a qualified specialist. Details: Terms of Service, point 4.

Example products

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Calculation method

A 38° spring (52/38 crown) on a 90° inside corner is about 31.6° miter and 33.9° bevel — the pair most US crown charts publish. Both angles shrink as the corner opens: a 135° bay corner is about 14.3° miter and 17.6° bevel, and a straight 180° joint needs neither. Outside corners use 360° minus the wall angle, so the same trig still applies.

Exact formula

miter = arctan(sin(spring) / tan(included/2)). bevel = arcsin(cos(spring) × cos(included/2)). Outside corners use included = 360° − wall.

Angles do not unit-convert

Degrees are the same in metric and imperial, so switching units changes nothing here. The tool always takes the wall corner in degrees; read it off an angle finder or protractor, whatever tape measure you use.

Frequently asked questions

My 45° crown does not match 31.6° / 33.9°.

Those numbers are for 38° spring (52/38 crown). 45° spring on 90° is about 35.3° miter and 30.0° bevel.

Do I flip the saw for left vs right?

Yes. The magnitudes stay; the miter direction and which face is against the fence change.

Should I cope inside corners?

Often. Cut one piece square and cope the profile; miter the outside corners.

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