How much crown molding do I need for a room?

Add up the length of every wall you will run crown along: for an 11 × 14 ft room that is 11 + 14 + 11 + 14 = 50 linear ft. Add 10 to 15% for waste (an estimate: crown has more cuts and miters than baseboard), divide by the piece length and round up. This calculator also packs the pieces wall by wall, so the 11 × 14 ft room comes to 7 pieces of 8 ft before waste, and 8 with 10% waste.

What miter and bevel angles do I use for crown molding on a 90° corner?

Cutting crown flat on a compound miter saw, 52/38 crown (38° spring) on a 90° corner takes a miter of 31.62° and a bevel of 33.86°, usually set as 31.6° and 33.9° on the saw. 45/45 crown takes 35.26° (35.3°) and 30.00° (30°). Choose the right spring angle first: the 52/38 settings will not fit 45/45 crown.

What is the formula for crown molding miter and bevel angles?

With s the angle the crown makes with the ceiling (52° for 52/38 crown, 45° for 45/45) and C the angle between the two walls: miter = arctan(cos s ÷ tan(C ÷ 2)) and bevel = arcsin(sin s × cos(C ÷ 2)). The calculator asks for the spring angle (38° or 45°), the angle between the back of the molding and the wall, so s = 90° minus the spring angle. These are the settings for crown cut flat with its back on the saw table.

What is the spring angle of crown molding?

It is the angle between the back of the molding and the wall. The common types are 38° (sold as 52/38: 52° against the ceiling, 38° against the wall) and 45° (45/45). Look at the profile from the end, or hold a bevel gauge against a piece to check it. A wrong spring angle gives gaps at every corner, so confirm it before cutting good stock.

What if my corners are not 90°?

Measure the angle between the two walls with an angle finder and enter it as the wall corner angle: the miter and bevel update. Walls of an eight-sided bay meet at 135°, and 45° spring crown there needs 16.32° miter and 15.70° bevel. Corners in an older house are rarely exactly 90°, so measure each one; a half degree off opens a visible gap. Charts for corners under about 60° are rare, so test those cuts in scrap.

Are the settings the same for inside and outside corners?

The two angles are the same. What changes is the direction: the table swings the other way and the blade tilts the other way, and you keep the other side of the cut. Saw makers print the layout in the manual, and a pair of short offcuts held in the corner shows quickly whether you have it right. Many carpenters cope the second piece of an inside corner instead of mitering both, which hides gaps when the walls move.

How do scarf joints work on a long wall?

When a wall is longer than one piece, two pieces are joined with a scarf joint: both ends are cut at a matching angle (usually 45°, in the same plane) and overlap, so the joint stays closed if the wood moves. Put the joint over a stud or nailer, and avoid very short pieces; the calculator never cuts a piece shorter than the minimum you set, and splits the last full piece with the end piece if it must. The 76 ft of an 8 × 30 ft hall on 16 ft pieces with a 36 in minimum needs 2 scarf joints and 6 pieces: 2 × 192 in; 2 × 168 in; 1 × 96 in + 96 in before waste.

How are the pieces and cut list worked out?

Each wall is cut from whole pieces, then all the pieces are packed onto stock lengths, longest first, each on the first piece with room, so an offcut can finish another wall. A 16 × 20 ft room on 12 ft pieces takes 6 pieces before waste (4 × 144 in; 2 × 96 in + 48 in), and 7 with 15% waste. Miter and kerf losses are not modeled, which is what the waste percentage is for.

How many inside and outside corners do I enter?

A plain rectangular room has four inside corners and no outside corners, which are the defaults. Add an outside corner for a chimney breast, a bump-out or a column. The calculator reports the number of corners and the mitered or coped ends they need (two per corner); it does not change the piece count, which comes from the walls and the waste.

How much waste should I allow for crown molding?

Ten to fifteen percent is the usual rule of thumb: 10% for a plain room with square corners and 15% for many corners, angled walls or a first job. This is an estimate, not a standard. Crown is expensive and hard to match later, so it is worth buying one spare piece when you are new to compound cuts, and always practising on offcuts.

Crown Molding Calculator: Pieces to Buy and Miter Saw Angles

An 11 × 14 ft room has 50 ft of wall, which takes 8 pieces of 8 ft crown molding with 10% waste (an estimate). Cut flat, 52/38 crown on a 90° corner is set to 31.62° miter and 33.86° bevel; 45/45 crown is 35.26° miter and 30.00° bevel.

Figures based on the sources listed belowUpdated 2026-10-12How we calculate

Room length

Room width

Waste (estimate)

Standard (10%, estimate)Many corners or first time (15%, estimate)Custom

Piece lengthThe length you will buy. Walls longer than a piece are joined with scarf joints.

Extra wall length (ft)

Walls beyond the four of the room above (an alcove, a bay or a hall), added as one more wall. Leave 0 for a plain room.

Shortest piece allowed (in)

No piece on a long wall is cut shorter than this, because short pieces are hard to fit and show the joint. 24 in is a rule of thumb, not a code figure.

Spring angleThe angle between the back of the molding and the wall. 52/38 crown has a 38° spring (52° against the ceiling); 45/45 crown leans at 45°. Check yours with a test block if unsure.

Wall corner angle (°)

The angle between the two walls, 90 for a square corner. Measure out-of-square corners with an angle finder; the corners of a 135° bay are entered as 135.

Inside corners

Corners where two walls meet and point away from you: all four in a plain room.

Outside corners

Corners that stick out into the room, such as a chimney breast or a bump-out.

Price per piece (optional)

Buy 8 pieces

50 linear ft + 10% waste = 55.00 linear ft

Total molding: 50 ft
Pieces (8 ft): 8 pieces, 7 before waste
Scarf joints: 4 joints, where a wall is longer than one piece
Cut list (first-fit, inches): 4 × 96 in; 2 × 72 in; 1 × 36 in + 36 in (before waste)
Inside corners: 4 corners, 8 mitered or coped ends
Outside corners: 0 corners
Miter angle (saw table): 31.62°
Bevel angle (blade tilt): 33.86°
Shortest piece: 36 in

How this number is calculated

50 linear ft + 10% waste = 55.00 linear ft ÷ 6.88 linear ft per piece = 8 pieces

Shopping list

Crown molding (primed MDF or poplar)
Compound miter saw
Crown molding miter saw jig
Digital angle finder
18-gauge brad nailer
Paintable caulk
Coping saw

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Miter and bevel settings by wall corner angle

Crown cut flat, back on the saw table; the angle between the two walls in the first column. Computed with the formulas in the methodology. Test on scrap: the direction of the miter and bevel differs for inside and outside corners.
Wall corner	38° spring: miter	38° spring: bevel	45° spring: miter	45° spring: bevel
60°	46.84°	43.03°	50.77°	37.76°
75°	38.74°	38.69°	42.66°	34.12°
90°	31.62°	33.86°	35.26°	30.00°
100°	27.32°	30.43°	30.68°	27.03°
120°	19.57°	23.20°	22.21°	20.70°
135°	14.31°	17.55°	16.32°	15.70°
150°	9.37°	11.77°	10.73°	10.55°

Pieces to buy for common rooms

Four walls, 10% waste (an estimate), shortest piece 24 in, worked by this calculator with scarf joints and a first-fit cut list.
Room	Wall total	8 ft pieces	12 ft pieces	16 ft pieces
10 × 10 ft	40 ft	6	5	5
10 × 12 ft	44 ft	7	5	5
12 × 12 ft	48 ft	7	5	5
12 × 14 ft	52 ft	8	6	5
14 × 16 ft	60 ft	9	6	5
16 × 20 ft	72 ft	10	7	6

Methodology & assumptions

The room gives four walls (length, width, length, width); an extra wall length, if you enter one, is added as a fifth wall. Each wall is cut from whole pieces of the stock length you pick, joined with scarf joints where the wall is longer than a piece. If the end piece of a wall would be shorter than your minimum, the last whole piece is taken back and split with it so the short piece is exactly the minimum. All pieces are then packed onto stock pieces, longest first, each on the first piece with room (first-fit decreasing), so an offcut from one wall can finish another. Miter and scarf kerf is not modeled. The waste percentage you choose (10% standard, 15% for many corners or a first job; both estimates, not standards) is added to the packed piece count and rounded up. The saw settings are for crown cut flat, back on the saw table. With s the angle the molding makes with the ceiling (52° for 52/38 crown, 45° for 45/45) and C the angle between the two walls, miter = arctan(cos s ÷ tan(C ÷ 2)) and bevel = arcsin(sin s × cos(C ÷ 2)). The calculator asks for the spring angle, the angle between the back of the molding and the wall (38° or 45°), which is 90° − s. For 38° spring on a 90° corner this gives 31.62° and 33.86°, and for 45° 35.26° and 30.00°, matching the common published saw charts (the charts round these to 31.6 and 33.9, and 35.3 and 30). The same two angles are used for an inside and an outside corner; the direction the table swings and the blade tilts reverses, and which side of the blade you keep changes, so make a test cut in scrap on your own saw. Saw detents and scales are only accurate to about half a degree: always test the fit on offcuts, and confirm the actual spring angle of your molding with a test block.

Crown molding angle charts, Starrett (instruction sheet for the crown molding miter and bevel chart): settings by wall corner angle for 38° and 45° spring crown, with different saw orientations for inside and outside corners
Published crown molding saw charts (several trade and tool-maker sites): for 52/38 crown on a 90° corner the miter is 31.6° and the bevel 33.9°, and for 45/45 crown 35.3° and 30°. The formulas on this page reproduce these to two decimals (31.62°, 33.86°, 35.26°, 30.00°)
Waste of 10 to 15% for crown molding, and one spare piece for a first job: a common rule of thumb in online crown molding calculators, not a standard (an estimate)
Scarf joints on long walls and a shortest piece of about 24 in: common practice, not a code or manufacturer figure (an unverified typical value; adjust it to your job)
Stock lengths: crown molding is commonly sold in 8, 12 and 16 ft pieces (an unverified typical range; check what your supplier stocks)

How to figure crown molding pieces and miter saw settings

Measure the walls. Measure each wall at the ceiling in feet. Enter the room length and width, and any extra wall length for an alcove or bay.
Pick the piece length and waste. Choose 8, 12 or 16 ft pieces and 10 or 15% waste, and set the shortest piece you are willing to cut. Walls longer than a piece are joined with scarf joints.
Enter the spring angle and corner angles. Choose 38° for 52/38 crown or 45° for 45/45 crown, and enter the wall corner angle (90° for a square corner; measure out-of-square ones). Count the inside and outside corners.
Read the pieces and cut list. Buy the number of pieces shown, and use the cut list to plan which wall each piece comes from.
Set the saw and test. Lay the crown flat with its back on the table, set the miter and bevel shown, and test a pair of offcuts in a real corner before cutting the good pieces.

Worked examples

Project	Result
11 × 14 ft room, 8 ft pieces, 10% waste, 52/38 crown on square corners	8 pieces (4 × 96 in; 2 × 72 in; 1 × 36 in + 36 in before waste); miter 31.62°, bevel 33.86°
16 × 20 ft room, 12 ft pieces, 15% waste	7 pieces (4 × 144 in; 2 × 96 in + 48 in before waste), 4 scarf joints
10 × 12 ft room with a 9 ft bay wall, 45/45 crown, 135° corners, 8 ft pieces, 10% waste	8 pieces (4 × 96 in; 1 × 84 in; 1 × 48 in + 48 in; 1 × 24 in + 24 in + 24 in before waste); miter 16.32°, bevel 15.70° at 135°
8 × 30 ft hall, 16 ft pieces, shortest piece 36 in, 10% waste	6 pieces (2 × 192 in; 2 × 168 in; 1 × 96 in + 96 in before waste), 2 scarf joints

Frequently asked questions

How much crown molding do I need for a room?: Add up the length of every wall you will run crown along: for an 11 × 14 ft room that is 11 + 14 + 11 + 14 = 50 linear ft. Add 10 to 15% for waste (an estimate: crown has more cuts and miters than baseboard), divide by the piece length and round up. This calculator also packs the pieces wall by wall, so the 11 × 14 ft room comes to 7 pieces of 8 ft before waste, and 8 with 10% waste.
What miter and bevel angles do I use for crown molding on a 90° corner?: Cutting crown flat on a compound miter saw, 52/38 crown (38° spring) on a 90° corner takes a miter of 31.62° and a bevel of 33.86°, usually set as 31.6° and 33.9° on the saw. 45/45 crown takes 35.26° (35.3°) and 30.00° (30°). Choose the right spring angle first: the 52/38 settings will not fit 45/45 crown.
What is the formula for crown molding miter and bevel angles?: With s the angle the crown makes with the ceiling (52° for 52/38 crown, 45° for 45/45) and C the angle between the two walls: miter = arctan(cos s ÷ tan(C ÷ 2)) and bevel = arcsin(sin s × cos(C ÷ 2)). The calculator asks for the spring angle (38° or 45°), the angle between the back of the molding and the wall, so s = 90° minus the spring angle. These are the settings for crown cut flat with its back on the saw table.
What is the spring angle of crown molding?: It is the angle between the back of the molding and the wall. The common types are 38° (sold as 52/38: 52° against the ceiling, 38° against the wall) and 45° (45/45). Look at the profile from the end, or hold a bevel gauge against a piece to check it. A wrong spring angle gives gaps at every corner, so confirm it before cutting good stock.
What if my corners are not 90°?: Measure the angle between the two walls with an angle finder and enter it as the wall corner angle: the miter and bevel update. Walls of an eight-sided bay meet at 135°, and 45° spring crown there needs 16.32° miter and 15.70° bevel. Corners in an older house are rarely exactly 90°, so measure each one; a half degree off opens a visible gap. Charts for corners under about 60° are rare, so test those cuts in scrap.
Are the settings the same for inside and outside corners?: The two angles are the same. What changes is the direction: the table swings the other way and the blade tilts the other way, and you keep the other side of the cut. Saw makers print the layout in the manual, and a pair of short offcuts held in the corner shows quickly whether you have it right. Many carpenters cope the second piece of an inside corner instead of mitering both, which hides gaps when the walls move.
How do scarf joints work on a long wall?: When a wall is longer than one piece, two pieces are joined with a scarf joint: both ends are cut at a matching angle (usually 45°, in the same plane) and overlap, so the joint stays closed if the wood moves. Put the joint over a stud or nailer, and avoid very short pieces; the calculator never cuts a piece shorter than the minimum you set, and splits the last full piece with the end piece if it must. The 76 ft of an 8 × 30 ft hall on 16 ft pieces with a 36 in minimum needs 2 scarf joints and 6 pieces: 2 × 192 in; 2 × 168 in; 1 × 96 in + 96 in before waste.
How are the pieces and cut list worked out?: Each wall is cut from whole pieces, then all the pieces are packed onto stock lengths, longest first, each on the first piece with room, so an offcut can finish another wall. A 16 × 20 ft room on 12 ft pieces takes 6 pieces before waste (4 × 144 in; 2 × 96 in + 48 in), and 7 with 15% waste. Miter and kerf losses are not modeled, which is what the waste percentage is for.
How many inside and outside corners do I enter?: A plain rectangular room has four inside corners and no outside corners, which are the defaults. Add an outside corner for a chimney breast, a bump-out or a column. The calculator reports the number of corners and the mitered or coped ends they need (two per corner); it does not change the piece count, which comes from the walls and the waste.
How much waste should I allow for crown molding?: Ten to fifteen percent is the usual rule of thumb: 10% for a plain room with square corners and 15% for many corners, angled walls or a first job. This is an estimate, not a standard. Crown is expensive and hard to match later, so it is worth buying one spare piece when you are new to compound cuts, and always practising on offcuts.

Handy tools

Feet and Inches Calculator: Add up walls measured in feet, inches and fractions, and get decimal feet for the room size above.
Decimal to Fraction Converter: Turn a decimal-inch cut length such as 47.3125 into the nearest 1/16 on a tape measure.