Crown molding angle calculator
Enter the crown's spring angle and the wall corner and this gives the miter and bevel to cut it flat on the saw, or the single miter to cut it nested. It is the compound-angle math the CutOnce app runs, the part a crown chart on the box can't do for an out-of-square corner.
Updated
The short answer
To cut crown flat on the saw at a square (90 degree) corner, use the numbers for its spring angle: a 38 degree crown cuts at 31.62 degrees miter and 33.86 degrees bevel; a 45 degree crown cuts at 35.26 miter and 30.00 bevel. For any other wall angle, or to cut it nested against the fence, enter the numbers above.
Spring angle is molded on the back of the crown (usually 38 or 45 degrees). Corner is the wall angle you measured; a square corner is 90. Cut flat and you set both the miter and the bevel; cut nested and the blade stays square (bevel 0).
- Miter (saw table)
- 31.62°
- Bevel (blade tilt)
- 33.86°
What the spring angle is
The spring angle is how far the crown leans out from the wall, and it is molded into the profile, not something you choose. Most crown is 38 or 45 degrees, sometimes 52, and it is usually stamped on the back or the box. It matters because a compound cut depends on both the spring angle and the wall corner: the same 90 degree corner needs a different miter and bevel for a 38 degree crown than for a 45. Get the spring angle wrong and the joint gaps even though the corner is square.
Flat versus nested
There are two ways to cut crown. Nested (or sprung) means you stand it up against the fence at its spring angle, upside down, and cut with the blade straight: one simple miter, no bevel, but you can only do it on stock short enough to stand up. Flat means you lay it on the table and cut a compound angle, a miter and a bevel together, which handles any length but needs both saw settings. This calculator gives you both: the compound pair for flat, or the single miter for nested.
A worked example
A 38 degree crown at a square inside corner, cut flat on the saw. Here is where the settings come from.
| Spring angle | 38° | given (molded in the profile) |
| Wall corner | 90° | given (square corner) |
| Miter (table) | 31.62° | atan2(sin S x cos(theta/2), sin(theta/2)) |
| Bevel (tilt) | 33.86° | asin(cos S x cos(theta/2)) |
The crown chart, square corners
Flat-cut miter and bevel for common spring angles at a square 90 degree corner. This is the chart printed on the crown box; for any corner that is not 90 degrees, measure it and use the calculator.
| Spring angle | Miter | Bevel |
|---|---|---|
| 38° | 31.62° | 33.86° |
| 45° | 35.26° | 30.00° |
| 52° | 38.24° | 25.81° |
Inside, outside, and out-of-square
Inside and outside corners use the same miter and bevel; what changes is which side of the line you keep and how the piece faces the saw, so cut them in mirrored pairs and label the keeper. The real reason to skip the printed chart is that walls are rarely a true 90 degrees. Measure the actual corner with a bevel gauge or an angle finder, enter it, and the compound settings follow. A 3 degree error at the wall is a visible gap in the crown.
Common questions
- What angle do I cut 38 degree crown at?
- At a square corner, 31.62 degrees miter and 33.86 degrees bevel cut flat on the saw, or a single 45 degree miter cut nested against the fence. Those are for a 90 degree wall; a corner that is not square needs its own numbers, which is what the calculator is for.
- What is the difference between the miter and the bevel?
- The miter is the saw table angle, how far you swing the arm left or right. The bevel is the blade tilt, how far the blade leans over from vertical. Cutting crown flat needs both set at once, which is why it is called a compound cut; cutting it nested needs only the miter, with the blade left square.
- Should I cut crown flat or nested?
- Nested is simpler (one miter, no bevel) and many finish carpenters prefer it for smaller crown, but you can only stand up stock short enough to fit under the saw at its spring angle. Wider crown, or long pieces, get cut flat with the compound settings. The calculator gives both so you can pick per cut.
- How do I handle a corner that isn't 90 degrees?
- Measure it. Use a protractor, a bevel gauge and a speed square, or an angle finder to get the actual included angle of the wall, then enter that as the corner. The compound miter and bevel update, because both settings depend on the true corner, not the 90 degrees the chart assumes.
- Why does the same corner need different angles for different crown?
- Because the spring angle changes how the profile meets the wall and ceiling. A 45 degree crown leans out more than a 38, so its face turns a different amount at the corner, and the saw has to compensate with a different miter and bevel. That is exactly why a single printed chart can't cover every crown, and the math has to take the spring angle as an input.
Cut the corner, trim the room
CutOnce runs these compound angles on the jobsite for any spring angle and any measured corner, draws the cut so you can see which way the piece faces, and it handles the rest of the trim and framing math too.
Free to download, with a 7-day trial of everything. The web calculator is the teaser; the app draws the cut.
See also