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How to Install Crown Molding

Crown molding is the one trim job where the saw settings are not obvious and not guessable. The molding leans out from the wall, so every corner is a compound cut, and the two numbers you need depend on the profile as much as the room.

By Lucas Pradella, builder and editor. Checked 2026-09-16.

Start with the spring angle, because it sets everything else

Crown does not sit flat against the wall. It leans out at a spring angle, which is a property of the profile rather than the room, and on nearly everything sold it is 38 or 45 degrees.

If the stock is not marked, hold a short offcut into the corner the way it will sit, mark where it touches the wall and the ceiling, and measure the two legs. Equal legs is 45 degree stock. A longer wall leg than ceiling leg is 38.

Get this wrong and every cut in the room is wrong by about four degrees, which is a gap you cannot caulk out on a painted ceiling line.

The two settings, and the formula behind them

A compound cut needs a miter setting and a bevel setting, and neither of them is half the corner angle. Both come out of two lines of trigonometry:

miter = arctan( sin(S) / tan(theta / 2) )
bevel = arcsin( cos(S) x cos(theta / 2) )

S is the spring angle of the stock, theta is the measured corner. Worked out for the corners you actually meet:

Read the square corner row and you have the two numbers most jobs need: 31.62 and 33.86 for 38 degree stock, 35.26 and 30.00 for 45 degree.

The chart everybody quotes has one wrong cell, and it is the one you need

L.S. Starrett publishes a compound cut conversion table with its 505P protractor: 60 rows, four columns, 240 printed values covering both spring angles. We checked every cell against the formulas.

It matches everywhere except one cell, and that cell is the 90 degree corner. For 38 degree crown at a square corner it prints a miter of 31.8 where the geometry gives 31.62. Its own neighbouring rows bracket the correct figure, which is what makes it look like a typographical error rather than a different method.

0.18 of a degree is not a disaster on one cut. It is doubled at every corner, because both halves carry it, and it lands on the most common cut in the room.

The lesson is not that Starrett is unreliable. Their table is right 239 times out of 240, which is better than most published charts manage. The lesson is that a chart is a transcription and the formula is the source.

Measure the corner. It is not 90

Drywall corners are rarely square, and crown sits at the top of the wall where the taping is thickest. Measure each corner near the ceiling with an angle finder rather than assuming.

The sensitivity is easy to state: one degree of corner error is about half a degree of miter error. A corner at 92 rather than 90 moves the 38 degree miter from 31.62 to 30.73, and cutting it at 31.62 leaves a gap that opens at the top or the bottom of the joint depending which way the error went.

This is why two identical rooms take different times. Measuring four corners costs five minutes; recutting four corners costs the afternoon.

Flat or nested, and why the answer changes with the stock

There are two ways to cut crown, and they use different numbers.

Flat on the table uses the miter and bevel pair above. It works at any width, and it is the only option once the crown is too wide to stand against the fence.

Nested means holding the piece upside down against the fence at the angle it will sit on the wall, then mitering at half the corner angle with no bevel: 45 degrees on a square corner. It is faster and there is only one setting to get wrong, but it needs stock narrow enough to nest and a fence tall enough to hold it.

The four cuts, and which way the saw swings for each

Two settings are not the whole instruction. A room has four different pieces meeting at corners: the left and right halves of an inside corner, and the left and right halves of an outside corner. Each one needs the miter swung one way, the bevel swung one way, the work held on one side of the blade, and one particular edge of the molding against the fence. Get any of the four wrong and the numbers were right for a piece you did not cut.

Starrett's protractor manual sets all four out for crown cut flat on the table. This is its list, tabulated:

Two things in that table are worth reading twice. The bevel always swings the same way for both halves of a corner, so once it is set for an inside corner it stays; only the miter changes side. And the edge against the fence flips between the two halves of every corner, which is the part that gets forgotten between the first cut and the second.

Cutting nested does the same job with the piece upside down and no bevel at all, which is why This Old House's carpenter prefers it. His rule, in that article, is that he seldom picks up a tape measure and marks cuts in place instead, because a measurement is one more place to be wrong.

Outside corners: find the angle with two offcuts, then bisect it

An outside corner is mitered, never coped, so its angle has to be found and halved. An angle finder does it. Without one, This Old House gives a method that uses nothing but two scraps of the same width and a pencil.

1. Hold one scrap flat to the ceiling along each wall so their ends overlap by an inch or so.
2. On the upper scrap, pencil a line along each edge of the lower one, then draw the diagonal that joins the two opposite corners of those marks.
3. Stack the two scraps exactly on top of each other with the marked one uppermost, put one set of edges against the saw fence and swing the blade until it lines up with the diagonal.
4. Cut both at once. The blade has bisected the corner, and the saw is now set for it.
5. Hold the two cut pieces up at the corner and check the fit. If it is open, note which way, adjust, and cut the stack again before touching any crown.

The two halves of an outside miter are both cut long on the top of the crown, the edge that sits on the saw table when the piece is upside down. Because the piece is inverted, a blade swung right cuts the right half of the joint and takes the right end of the workpiece; swung left, the left half. That is the same rule as the Starrett table above, expressed for a nested cut.

Before nailing, This Old House bores two pilot holes through the point of the miter, glues the joint, then fastens each piece with finish nails top and bottom and taps finish nails through the pilot holes at the corner. The pilot holes are what stop the tip of the miter splitting, which is where an outside corner fails first.

Cope the inside corners, and how the cope is cut

A mitered inside corner is two compound cuts meeting. A coped corner is one piece cut square into the corner and the second profiled to sit over it.

The trade preference is not about beauty, it is about tolerance. A miter opens when the corner is out of square and again when the timber shrinks. A cope hides both, because only the profile line shows and it is cut to fit the piece it meets rather than to a number.

The cut itself, as This Old House describes it:

1. Install the first piece with a square end butted into the corner: zero degrees on the saw.
2. Put the second piece upside down on the saw and miter it at 45. If it meets the corner from the right, swing the blade 45 left with the bulk of the piece on the left; if from the left, swing right with the piece on the right.
3. Run a pencil along the very edge of the cut on the profiled face, so the line to follow shows.
4. With a coping saw, cut away the bevel along that line, angling the blade back about five degrees so only the front edge of the profile touches the piece it meets. Brace the work on the saw table while cutting.
5. Test it against the square-cut piece already nailed up, take more off with a rasp where it stands proud, then nail it and set the nails.

The back bevel is the detail that makes a cope forgiving. Only a knife edge of profile meets the first piece, so a corner a degree or two out of square closes anyway.

Outside corners get mitered either way, so the angles above still matter on every external return.

Buying: perimeter, waste and where the joints land

Quantity is the room perimeter plus an allowance, then divided by the stock length, which is where people under-buy. Crown comes in fixed lengths, commonly 8, 12 and 16 ft, and a wall longer than the stock needs a joint in the middle of the run.

That joint is a scarf, not a butt: both ends mitered at 45 degrees in the same direction so they overlap. A butt joint opens into a visible line as soon as the timber moves; a scarf stays closed because the overlap slides rather than parting.

This Old House cuts a scarf with the crown upside down between the fence and a wood guide, 45 degrees to the left when working counterclockwise round the room and to the right when working clockwise, keeping the piece on the side the blade is turned to. The second length is cut with the blade left where it is and the keeper on the other side. The joint is glued, both pieces nailed top and bottom, the squeeze-out wiped, and the joint sanded with 100 grit once the glue has dried.

So the longest stock the room and the van will take is the right answer. A 16 ft wall in 8 ft lengths has a scarf in it. In 16 ft stock it does not.

The 10% waste allowance on our calculator is this site's default rather than a manufacturer's figure, and the page says so. This Old House uses the same 10% on top of the measured perimeter. Corners eat offcuts, and a mis-set bevel eats a whole length.

The order of the day

Cut order matters more than speed. A sensible sequence for a rectangular room:

1. Measure every corner, write the number on the wall under it.
2. Confirm the spring angle from an offcut.
3. Mark the ceiling line by holding a piece in place, so you can see where the crown will actually land and where it will cross a bad ceiling.
4. Start on the wall opposite the door, where a joint is least visible.
5. Cut one piece at a time and offer it up before cutting its partner.
6. Fasten into framing where you can find it, and into the ceiling and wall plates where you cannot.
7. Leave scarf joints until last on a long wall, so the two pieces can be adjusted together.

Corners are what the job costs. The linear feet barely move with the shape of the room, but a room with a bay window has fourteen compound cuts against a plain rectangle's eight, and each one is a separate setup on the saw.

Where the crown stops: returns, nails and filling

Crown that ends in open air, at a door head or a change of ceiling height, is finished with a return: a tiny mitered triangle that turns the profile back into the wall so the end shows a face rather than an end grain.

1. Miter the end of the run at 45 degrees, as for an outside corner, and nail it up.
2. Cut a 45 in the opposite direction on a second piece.
3. Set the saw to zero, lay that piece flat and face down on the table with the guide fence removed, and cut through it starting exactly at the point of the miter. What drops off is the return.
4. Bore two pilot holes through it with a finish nail, glue it, and press it into place for a minute or two. This Old House nails it through the pilot holes only if the glue does not hold.

Fastening. Find and mark the studs with a stud finder before the first piece goes up, and draw a level line where the bottom of the crown will sit and a mark on the ceiling where the top will touch. Each piece gets finish nails along the top and along the bottom, into the ceiling framing and the wall plate. Set every nail and fill the holes.

Filling. Gaps under a quarter inch at the wall or ceiling line are caulked. Larger ones take wood filler or a thin strip of wood as a shim, sanded and painted to blend. Where a ceiling dips so far that neither works, This Old House's answer is a backer rod behind the molding, and in extreme cases floating the surface flat before the crown goes up. None of those is a reason to change the saw settings: a bad ceiling is filled, not cut to.

What it costs, from a dated guide

HomeAdvisor's crown molding guide, updated 17 June 2026 and reviewed by Andy Kilborn, prices the job per linear foot: $4 to $23 installed, of which installation labor is $3 to $12. Material by type runs from $1 to $4 per foot for PVC or foam up to $10 to $30 for metal.

Worked on a 12 by 14 ft bedroom, 52 ft of perimeter: $208 to $1,196 installed at the guide's rate, and about 58 ft of stock to buy with the 10% allowance. The same room with a bay window has more corners but barely more feet, which is the point made above: the guide's per foot rate cannot see the fourteen compound cuts, and a quote for that room should sit toward the top of the range on labor.

One thing the guide does not reconcile: its installed rate tops out at $23 a foot while its own solid wood material row reaches $30 before any labor. Hardwood crown is priced by the material row plus the labor row, not by the installed range.

Source: HomeAdvisor, how much does crown molding installation cost. Last price check: 2026-09-13.

What this guide does not cover

It does not price a specific room. The HomeAdvisor rates above are national ranges per foot, and the guide gives no method behind them; the calculator page carries the same table and multiplies it by your perimeter.

It does not cover built-up crown, lighting coves or curved walls, all of which are different geometry. This Old House's answer for a curve is flexible molding, or relief cuts on the back of wood stock, and a cardboard template of the curve first.

And it does not tell you the spring angle of your stock. Measure it, because a chart cannot see what you bought.

Run the numbers

Frequently asked questions

What angle do you cut crown molding?

For 38 degree stock in a corner that measures exactly 90, miter 31.62 and bevel 33.86. For 45 degree stock, miter 35.26 and bevel 30.00. Those are settings for cutting the molding flat on the saw table, and they change with the measured corner.

What is a spring angle?

The angle at which the crown leans out from the wall when it is installed. It is a property of the profile, normally 38 or 45 degrees, and it is what makes a corner cut compound instead of a simple miter.

Is the published crown molding angle chart reliable?

Starrett's 240 value table matches the geometry 239 times. The exception is 38 degree crown at a square corner, where it prints a miter of 31.8 against a true 31.62, with the rows either side correct.

Why does my crown molding corner not close?

Usually because the corner is not 90 and the cuts assumed it was. One degree of corner error is about half a degree of miter error, which shows as a gap at the top or the bottom of the joint.

Can I cut crown without a compound miter saw?

Yes, by cutting it nested: held upside down against the fence at the angle it will sit on the wall, mitered at half the corner angle with no bevel. It needs stock narrow enough to nest and a tall fence.

Should I cope or miter inside corners?

Cope where the walls are out of square, because only the profile line shows and it is cut to fit rather than to a number. Miter where the corners are good and speed matters. Outside corners are mitered either way.

How do I join two pieces on a long wall?

With a scarf joint: both ends mitered at 45 degrees in the same direction so they overlap. A butt joint opens into a visible line as the material moves.

How much crown molding should I buy?

The room perimeter plus a waste allowance, then divided by the stock length and rounded up per wall. A wall longer than one stock length forces a joint, so longer stock means fewer joints.

How much does crown molding cost per foot?

HomeAdvisor's June 2026 guide gives $4 to $23 per linear foot installed, with labor at $3 to $12 of that. Material alone is $1 to $7 for MDF, $2 to $10 for polyurethane and $3 to $30 for solid wood. A 52 ft room is $208 to $1,196 installed at those rates. Last price check: 2026-09-13.

How do you finish crown molding where it ends?

With a return: miter the end of the run at 45, cut the opposite 45 on a scrap, then cut that scrap square, flat and face down, starting at the point of the miter. The small triangle that drops off is glued into the end so the profile turns back to the wall.

Do you nail crown molding into the studs?

Yes, and into the ceiling framing. Mark the studs with a stud finder before the first piece goes up, then run finish nails along both the top and the bottom edge of each piece, set them and fill the holes. Outside corners and returns get pilot holes first so the miter tips do not split.

How do you find an outside corner angle without an angle finder?

Hold two scraps of the same width to the ceiling, one along each wall, overlapping by an inch. Mark the upper one along both edges of the lower one, draw the diagonal between the opposite corners of the marks, stack the scraps and cut both along that line. The saw is then set to half the corner angle.

Check these numbers yourself

• A Perfect Crown Molding with your Starrett 505 Protractor, user manual PKG08595 UM505APThe L.S. Starrett Company. The 60 row compound cut conversion table for 38 and 45 degree crown, the saw swing and fence orientation for all four pieces at inside and outside corners, and the one cell that disagrees with the geometry. Read 2026-09-09.
• How To Install Crown MoldingWritten by Joseph Truini, This Old House, updated 8 October 2024. Read 2026-09-16. Source of the nested cutting method, the two-scrap way to bisect an outside corner, the coping, scarf and return steps, the nailing and filling advice, and the 10% waste allowance. Not used for prices.
• How Much Does Crown Molding Installation Cost?HomeAdvisor, written by staff writer, reviewed by Andy Kilborn, updated 2026-06-17, read 2026-09-13. The per linear foot rates in the cost section.

Figures here last checked against the source documents on 2026-09-16. Codes are amended locally; confirm against the edition your jurisdiction enforces.

Every guide on this site: Guides.