Crown Molding Miter & Bevel Calculator

Compound miter-saw settings for crown molding cut laid flat: miter-table swing and blade tilt from the spring angle (38°, 45°, 52° presets or custom) and the measured corner angle, with the miter direction and saved end spelled out per piece for inside and outside corners, plus the simple nested-cut miter for reference.

Compound-angle identities · DeWalt crown chart · SBE Builders tables

Molding & Corner

Spring angle preset
deg
deg

US-standard 52/38 crown springs at 38°. The corner angle is the included wall-to-wall angle: 90° for a square corner, 135° for a standard bay wall, 180° for a straight run. Measure the real corner — drywall is rarely a true 90°.

Saw Settings — Crown Laid Flat

31.6°
miter (table swing)
33.9°
bevel (blade tilt)
miter RIGHT, save LEFT end
Left piece (inside corner)
miter LEFT, save LEFT end
Right piece (inside corner)
45.0°
Nested-method simple miter

Cut face up, laid flat, TOP of the molding against the fence — the bevel tilts the same way for every cut. miter = atan(sin S / tan(C/2)), bevel = asin(cos S × cos(C/2)). The nested miter applies only with the crown upside-down and backwards between fence and table (no bevel). Always test-cut on scrap: stock spring angle and real corner angles shift the fit.

About Crown Molding Miter & Bevel Calculator

The crown molding miter and bevel calculator gives the compound miter-saw settings for cutting crown molding laid flat on the saw table. Enter the spring angle — the angle the molding leans off the wall, 38° for standard US 52/38 crown, 45° or 52° for the other common profiles — and the corner angle between the walls, and the tool computes the miter-table swing and blade-tilt (bevel) from the compound-angle identities: miter = atan(sin S ÷ tan(C/2)) and bevel = asin(cos S × cos(C/2)).

For a standard 38° spring crown in a square 90° corner the answers are the famous 31.62° miter and 33.86° bevel — the numbers most compound miter saws carry as factory detents. The calculator also shows which way to swing the miter and which end of the cut to keep for the left and right pieces of inside and outside corners, and the simple one-angle miter (half the corner’s deviation) for cutting crown nested upside-down and backwards against the fence.

How It Works

  1. Pick the spring angle. US standard crown is 52/38 stock: it touches the wall 38° off vertical, so the spring angle is 38°. Many profiles use 45°, and 52°-spring stock exists too — use the preset buttons or type any angle from 30° to 60°. If you are unsure, set the crown in a framing square: the drop from the ceiling and the run along the wall identify the profile.
  2. Enter the corner angle between the walls as the included angle: 90° for a square corner, more for bay windows and cathedral transitions (a standard 45° bay wall meets at 135°), less for acute alcoves. Measure with a protractor or angle finder — drywall corners are rarely a true 90°, and a degree of error is visible in the joint.
  3. Choose inside or outside corner. The miter and bevel angles are identical for both — what changes is the direction you swing the miter table and which end of the cut you keep, and the tool spells both out for the left-hand and right-hand pieces (cut face up, laid flat, with the top of the molding against the fence).
  4. Set the saw: swing the miter table to the miter angle in the indicated direction, tilt the blade to the bevel angle, and cut with the molding flat on the table. The nested-cut miter is shown for reference if you prefer the upside-down-and-backwards method — there the saw does a plain miter at half the corner deviation and no bevel at all.
  5. Always pretest on scrap. Saw detents, spring-angle tolerance in the stock, and out-of-square corners each shift the fit; published saw charts and this calculator agree to 0.1°, but the room decides the final half degree.

Worked Example

Hang standard 52/38 crown (38° spring) around a square inside corner. With S = 38° and C = 90°: miter = atan(sin 38° ÷ tan 45°) = atan(0.6157) = 31.62°, and bevel = asin(cos 38° × cos 45°) = asin(0.7880 × 0.7071) = asin(0.5572) = 33.86° — exactly the 31.62°/33.85° crown detents machined into compound miter saws. Cut the left piece with the miter table swung right 31.62°, keep the left end of the cut; cut the right piece with the table swung left, keep the left end. For the nested method instead, set a plain 45° miter — (180° − 90°)/2 — with the crown upside-down and backwards against the fence.

Formulas

Flat-cut miter angle
miter = atan( sin S / tan(C / 2) )
Flat-cut bevel angle
bevel = asin( cos S × cos(C / 2) )
Nested-cut simple miter
miter_nested = (180° − C) / 2

Standards & References

  • Compound-angle trigonometric identities (the crown-molding special case of the Machinery's Handbook compound-angle relations), corner angle taken as the included wall-to-wall angle
  • DeWalt crown molding chart / miter-saw manuals — 31.62° miter and 33.85° bevel factory presets for 38° spring crown in 90° corners, and the flat-cut piece-orientation table (top of molding against the fence)
  • SBE Builders crown molding tables — digit-verification anchors across 60–135° corners for 38°, 45°, and 52° spring angles

Frequently Asked Questions

What miter and bevel do I set for standard crown molding in a 90° corner?

For US-standard 52/38 crown (38° spring angle) cut flat, set the miter to 31.62° and the bevel to 33.86° — most compound miter saws have detents at exactly 31.62° and 33.85° for this cut. For 45° spring crown the settings are 35.26° miter and exactly 30° bevel.

What is the spring angle and how do I find mine?

The spring angle is how far the crown leans off the wall when installed — the angle between the back of the molding and the wall. US 52/38 stock touches the ceiling at 52° and the wall at 38°, so its spring angle is 38°; 45/45 stock springs at 45°. Set a piece in a framing square the way it will sit between wall and ceiling and read which flat lands where, or check the profile drawing on the bundle.

Are the settings different for inside and outside corners?

The miter and bevel magnitudes are identical — only the direction of the miter swing and which end of the cut you keep change. Cut face up and laid flat with the top of the molding against the fence: for an inside corner the left piece miters right and the right piece miters left, keeping the left end of each cut; for an outside corner the directions and saved ends mirror.

What is the "upside-down and backwards" (nested) method?

Instead of laying the crown flat and cutting a compound angle, you stand it at its installed angle between the fence and the table — upside down, so the ceiling flat sits on the table and the wall flat against the fence. The saw then needs only a plain miter at half the corner deviation — 45° for a square corner, (180° − corner)/2 in general — and no bevel. It is faster to set but limited by the crown width your saw can nest.

My corner is not 90°. What angle do I enter?

Enter the included angle the two walls actually make — measure it with an angle finder rather than assuming. A standard bay window wall meets at 135°, and drywall corners routinely run 88–92°. The calculator accepts 60° to 180° and recomputes both settings from the identities, matching the published saw-chart tables row for row.

Why should I still test-cut on scrap?

Because three tolerances stack against you: the saw's detents and scales, the spring angle of the actual stock (profiles vary by a degree or two), and the true corner angle of the room. Saw manufacturers print the same warning on their crown charts — dial in the calculated settings, cut two short scraps, and check the fit in the actual corner before committing molding.