Compound Miter Calculator
Calculate crown molding miter and bevel angles for cutting flat. Enter the wall corner and spring angle, then check the illustrated 38° crown example.
Set up your calculation
An illustrative example is loaded. Replace its values with your measurements, costs or documented settings.
Calculation
Your result
- Saw miter magnitude
- 31.62 °
- Blade bevel magnitude
- 33.86 °
The quote handoff carries your inputs and assumptions. Only an explicit base cost is suggested as a quote cost; prices, rates and measurements remain planning notes.
Measure the two input angles first
Measure the wall corner
Use the included angle where the two walls meet. A square inside corner is 90°. Do not enter the saw-table miter setting here.
Measure spring from the wall
Read the crown’s installed angle from the wall, not the ceiling. Mark the wall and ceiling contact edges so that reference stays clear.
Identify the piece before cutting
Mark inside or outside corner, left or right piece, and the finished side to keep. Use your saw’s orientation chart and fit a scrap pair first.
Keep the result with the work
Copy or print the result with its measurements and assumptions. The quote handoff can retain these angles as planning notes; it does not treat degrees as a cost.
Method & assumptions
Miter = atan(sin(spring) ÷ tan(corner ÷ 2)). Bevel = asin(cos(spring) × cos(corner ÷ 2)). Spring is measured between the molding and wall.
- For crown molding held flat, with equal profiles on both sides of the corner. A 90° corner and 38° spring produce 31.62° miter and 33.86° bevel.
- These are angle magnitudes. Inside/outside corners and left/right pieces change direction and which edge faces the fence. Follow the saw’s crown-cut orientation chart and verify offcuts.
Cut 38° crown for a 90° wall corner
| Input or step | Example value |
|---|---|
| Included wall corner | 90° |
| Spring angle measured from the wall | 38° |
| Miter magnitude | 31.62° |
| Bevel magnitude | 33.86° |
| Cutting position | Crown lying flat on the saw table |
These magnitudes match the calculator’s loaded example. They do not specify left/right settings or which offcut to keep. Use your saw’s crown orientation chart and test matching scrap before cutting the finished molding.
Common questions
Do I enter 38° or 52° for 38/52 crown?
Enter the angle between the installed crown and the wall. For a profile installed at 38° from the wall, enter 38°. Its angle from the ceiling is 52°; those inputs are not interchangeable.
Can I use these settings with crown nested against the fence?
No. These formulas are for cutting crown flat with both miter and bevel. Nested cutting uses a different setup; follow the saw manufacturer’s instructions.
Does this calculate every compound woodworking joint?
No. This tool covers equal-profile crown molding at a wall corner. Use the framing-angle calculator for flat frames and the bevel-angle calculator for a bevel from a measured offset.
What if my corner is not exactly 90°?
Measure the included wall angle and enter it. Keep the spring angle referenced to the wall, then confirm the joint on scrap with the intended left and right orientations.
Learn the method in the Academy
Follow the matching lesson or workshop reference before applying the result.
Use this in your project
Continue with the next measurement or cost, then keep the assumptions with your quote.
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