How to cut crown molding flat
Cutting crown flat on the saw table means one miter and one bevel instead of holding the piece nested against the fence. Find the spring angle, set the two compound angles, lay the molding face up and flat, and cut. Worked for a standard 38 degree crown at a square corner.
Updated
Skip the arithmetic
Any spring angle, any measured corner, inside or outside: the crown molding angle calculator returns the exact miter and bevel to dial into the saw.
The short version
To cut crown flat, you set both a miter and a bevel on the saw. For a standard 38 degree spring crown at a square 90 degree corner, the miter is 31.62 degrees and the bevel is 33.86 degrees. Lay the molding face up and flat on the saw table, cut those two angles, and mirror the miter direction between inside and outside corners. The alternative, cutting nested, holds the piece against the fence at its spring angle and uses a single miter with no bevel.
Step by step
The two saw settings come from the spring angle and the corner angle. Both figures below are computed by the same code the app runs, not typed in.
- 01
Find the spring angle
The spring angle is how far the crown leans off the wall, and it is stamped on the profile or printed on the box: almost always 38 degrees or 45 degrees. Set the molding into a square against the wall and ceiling, measure the leg on the wall against the leg on the ceiling, and the ratio tells you which. Get this wrong and every cut is off.
- 02
Choose flat over nested
Cutting flat lays the molding face up on the saw table, which is steadier for wide crown and lets you cut long stock a chop saw could not hold on edge. The trade is that you set two angles, a miter and a bevel, instead of the single miter you would use holding the piece nested against the fence.
- 03
Measure the actual corner
Walls are rarely a true 90 degrees. Read the corner with a protractor or an angle finder and halve it for the joint. This page's table assumes a square corner; for anything off square, feed the measured corner to the calculator and it returns the adjusted miter and bevel.
- 04
Set the miter and the bevel
For a 38 degree crown at a square corner, set the saw miter to 31.62 degrees and tilt the blade to a 33.86 degree bevel. A 45 degree crown at the same corner is 35.26 miter and 30.00 bevel. Dial both in and lock them before the molding touches the blade.
- 05
Lay the molding flat, face up
Set the crown flat on the table, finished face up, with the edge that meets the ceiling toward the fence and the edge that meets the wall toward you. Keep that orientation constant so left and right cuts stay consistent, and mark the keeper end of each piece before you cut.
- 06
Mirror the direction for inside and outside corners
An inside corner and an outside corner use the same miter and bevel magnitudes but swing the miter the opposite way and keep the piece on the opposite side of the blade. Cut a scrap test corner from offcuts first, check the fit, then run the real stock.
Flat-cut miter and bevel at a square corner
The two compound angles for the common spring angles, cut flat at a square 90 degree corner. A 52 degree crown appears when a 52/38 profile is run with its steeper edge against the wall. For out-of-square corners, the calculator adjusts both numbers.
| Spring angle | Miter | Bevel |
|---|---|---|
| 38° | 31.62° | 33.86° |
| 45° | 35.26° | 30.00° |
| 52° | 38.24° | 25.81° |
Why the two numbers are what they are
The flat-cut miter is atan2(sin(spring) x cos(half corner), sin(half corner)) and the bevel is asin(cos(spring) x cos(half corner)). At a 38 degree spring and a square corner that resolves to the familiar 31.62 and 33.86 the crown charts print. The app and this page run the same tested formula, which is why the saw settings match what the app draws on the jobsite.
Common questions
- What angle do you cut crown molding flat?
- For the common 38 degree spring crown at a square corner, the saw miter is 31.62 degrees and the bevel is 33.86 degrees. A 45 degree spring crown is 35.26 miter and 30.00 bevel. Both assume a true 90 degree corner; out-of-square walls change the numbers.
- What is the difference between cutting crown flat and nested?
- Flat lays the molding face up on the saw table and uses a compound cut, a miter plus a bevel. Nested holds the molding against the fence at its spring angle and uses one miter with no bevel. Flat is steadier for wide crown; nested is faster when the piece fits against the fence.
- How do I find the spring angle of my crown?
- Stand the molding into a square where the wall and ceiling meet and compare the leg resting on the wall to the leg resting on the ceiling. Equal legs are a 45 degree spring; a longer wall leg is a 38 degree spring. It is usually printed on the box as well.
- Do inside and outside corners use different angles?
- The miter and bevel magnitudes are the same at a given corner angle; what changes is the direction of the miter and which side of the blade the keeper piece sits on. Cut a test corner from scrap to confirm the direction before the finish stock.
Cut the corner, trim the room
The app runs these compound angles for any spring and any measured corner, draws the cut so you can see which way the piece faces, and handles the rest of the trim and framing math.
See also