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Crown molding calculator

Enter the room to see how many feet and sticks of crown to buy, plus the miter and bevel settings for your corners.

Checked Nov 20262 sources citedSee the working
Stick length

Long sticks avoid joints on a long wall. Check what your store stocks.

Spring angle

The angle between the molding's back and the wall. 38 degrees is common, and so is 45.

90 is a square corner. A bay is often about 135.

Everything is worked out in this page. Nothing you type is sent.

Units

Enter and read measurements in feet, inches and yards.

Drawn to scale
14 ft12 ft57.2 ft to buy
Crown to buy
57.2
feet
Sticks to buy
4
Miter setting
31.6
degrees
Bevel setting
33.9 degrees
Inside corners
4 corners
Joints on long walls
0 joints
Perimeter
52.0 ft

My project list

0 items

Add this, then whatever else the job needs. Everything you need to buy ends up here.

Next for this job
Square footageLumens calculator for a room

How we got 57.2 ft

  1. Perimeter52.0 ft
  2. With the extra for waste57.2 ft
  3. Sticks4
  4. Saw settingsmiter 31.6, bevel 33.9 degrees

Figures used

Extra to add for waste, in percent
10
Common stick lengths for molding, in feet
see the table below
How many more inside corners than outside corners a closed square-cornered room has
4
Degrees in one radian
57.29577951308232

2 sources cited further down. Checked Nov 2026 by Anil, developer of this site.

Working

How to measure for crown

Measure each wall as high up as you can reach, near the ceiling, because that is the line the crown has to follow. A wall that looks straight at the floor can be out by half an inch at the top. Write each wall on a sketch, since you will want those numbers when you plan the sticks.

Crown runs over doors, so unlike baseboard, nothing comes off for them. Note any bump-outs or chimney breasts, as each adds two outside corners and more cuts. Then check your corners with an angle finder, because that is what the settings on the saw depend on, and a corner in an old house can be several degrees off a true 90.

14 ft12 ft57.2 ft to buy
A 14 by 12 ft room has 52 ft of wall, so 57.2 ft of crown with 10 percent extra.

Next, find the spring angle of the molding you bought. Hold a piece up to a framing square as if it were against the wall and ceiling. Most profiles are 38 or 45 degrees. Getting this wrong throws off every cut, and it is the first thing to check if your test pieces will not close.

A worked example

Here is a 14 by 12 foot room with square corners, in 16 foot sticks and a 38 degree profile. These lines come from the same formula the calculator above runs.

14 by 12 ft room, 16 ft sticks, 38 degree spring

  1. Perimeter: 2 × (14 + 12) = 52 ft
  2. With 10% extra: 57.2 ft
  3. Sticks: 4
  4. Miter: 31.6 degrees, bevel: 33.9 degrees

Those are the settings Bosch prints for a square corner at 38 degrees. On a 45 degree profile they become 35.3 and 30.0. Enter your own corner, as a corner that really measures 92 gives different numbers again. For the wall below it, see the baseboard calculator, and the paint calculator for the room.

Crown for common rooms

These are plain rectangular rooms, with 10 percent added. The 16 foot column avoids joints in any of these rooms, as long as your store has them and you can get them home.

Worked out by this calculator. Feet, and sticks by length.
RoomPerimeterTo buy16 ft sticks8 ft sticks
Small bedroom, 10 × 104044.046
Bedroom, 12 × 124852.847
Main bedroom, 14 × 125257.248
Living room, 16 × 125661.648
Large living room, 20 × 146874.8510
Dining room, 12 × 104448.447

Mistakes that spoil a run of crown

  • Trusting a square corner. Bosch's table assumes a corner of exactly 90. Few are. Use the number from an angle finder, and test on scrap.
  • The wrong spring angle. A 45 degree crown cut at 38 degree settings will not close. Check before you cut anything you need.
  • Joints where you will see them. Eight foot sticks on a 14 foot wall mean a joint. Long sticks cost more and look better.
  • Nothing spare on a first attempt. A compound cut takes practice, and scrap is cheaper than a second trip to the store.
  • Cutting upside down. Mark the top edge of each piece, and set the piece on the saw the same way every time.

Questions

How much crown molding for a 12x12 room?

A 12 by 12 room needs about 52.8 feet of crown, which is 48 feet of wall plus 10 percent. That is four 16 foot sticks, or seven 8 foot sticks with joints. Nothing comes off for doors, since crown runs over them.

Why buy extra crown molding?

You buy extra because compound cuts go wrong, and a bad cut on a short piece cannot be fixed. This Old House and Alexandria Moulding both suggest 10 percent. Allow more on a first project, since practice cuts use up material.

What angle do I cut crown molding?

For a square corner with the molding flat on the saw, use miter 31.6 and bevel 33.9 for a 38 degree spring angle, and miter 35.3 and bevel 30 for 45 degrees. Those are Bosch's printed settings. Always test on scrap, since real corners are rarely exactly 90.

How do I find the spring angle?

Hold the molding in a framing square as it would sit against the wall and ceiling, and measure the angle between its back and the wall. Many profiles are 38 or 45 degrees, and the label or the maker's data may list it.

How much does crown molding cost per room?

At an installed figure of $4 to $23 per foot, a 12 by 12 room with 48 feet of wall is about $190 to $1,100, using This Old House's project range. Enter your own price per foot in the further options to see the cost of your material.

What size crown molding for 8 foot ceilings?

We did not find a primary source that sets a rule for this, so we will not give you one. It is a matter of proportion. Hold a short sample at the ceiling and look at it from across the room before buying.

This crown molding figure is a planning estimate, and the saw settings assume a corner of the angle you typed, when real corners are rarely true. Always take a test cut on scrap first, follow your saw's manual, and check the spring angle on the profile. Ask your supplier what lengths it comes in, and read the label before cutting.

Sources and review

Checked in November 2026. Spotted a wrong number? Report it and it goes in the corrections log.

How this is calculated

Every figure below is read from the code that produces the answer, so what is written here is what the calculator ran. The constants were last checked against their sources in November 2026.

The arithmetic

Crown to buy

Feet = (2 × (Length + Width) + Extra wall) × (1 + Extra ÷ 100)

Extra
Percent added for waste, normally 10

Worked through: 2 × (14 + 12) = 52, and 52 × 1.1 = 57.2 ft

Miter setting

Miter = arctangent(sin(Spring) ÷ tan(Corner ÷ 2))

Spring, Corner
The spring angle and the corner angle, in degrees

Worked through: Spring 38, corner 90 gives 31.6 degrees

Bevel setting

Bevel = arcsine(cos(Spring) × cos(Corner ÷ 2))

Spring, Corner
The spring angle and the corner angle, in degrees

Worked through: Spring 38, corner 90 gives 33.9 degrees

The constants, and where they come from

SUGGESTED_WASTE_PERCENT

Published range, narrowed

Extra to add for waste, in percent

10

Applies to: Crown molding in a room with ordinary corners

Source: How to install crown molding, This Old House, published 2024-10, read 2026-11. This source is about 2 years old, and it is the one the figure rests on.

Also from: Moulding FAQ on product page 02189, Alexandria Moulding, no date on the page, read 2026-11.

This Old House and Alexandria Moulding both say 10 percent. Higher figures appear on thin sites and in one retailer's page we could not read. Add more for a first attempt.

COMMON_STOCK_FEET

Published range, narrowed

Common stick lengths for molding, in feet

0
8
1
12
2
16

Applies to: Common retail stock. Lengths vary by profile and by store

Source: Alexandria Mouldings collection FAQ, Windsor Plywood, no date on the page, read 2026-11.

Stated by a retailer for moldings in general, and not for crown alone, so check your store.

INSIDE_MINUS_OUTSIDE

Definitional

How many more inside corners than outside corners a closed square-cornered room has

4

Applies to: A closed room whose corners are all right angles

True by definition, so there is nothing to cite. The derivation is below.

Walking all the way round a room you turn 360 degrees, and each inside corner minus each outside corner is 90, so the difference is 4.

DEGREES_PER_RADIAN

Definitional

Degrees in one radian

57.29577951308232

Applies to: Definitional, everywhere

True by definition, so there is nothing to cite. The derivation is below.

A half turn is 180 degrees or pi radians, so one radian is 180 divided by pi. The angle formula is our own trigonometry, checked against Bosch's printed saw settings.

What the labels mean

Published range, narrowed:
a source publishes a range and this calculator uses a representative value from it.
Definitional:
true by definition, like the number of inches in a foot, so there is nothing to cite.

If a figure here looks wrong, it may be. Tell us what you found and we will check it against the source and publish a correction if it needs one. How constants are chosen and how often they are reviewed is set out in our methodology.

How to use the crown molding calculator

  1. 1

    Measure each wall along the ceiling, where the crown will sit

  2. 2

    Choose the stick length your store stocks

  3. 3

    Find the spring angle by holding the molding in place, or read the label

  4. 4

    Read the feet, the sticks and the saw settings

  5. 5

    Cut a test piece from scrap and check it against the real corner

What this calculator assumes

Every estimate here rests on the assumptions below. Where your job differs from one of them, the figure will differ too.

  • A rectangular room plus any extra wall. Crown runs over doors, so nothing is taken off for them
  • 10 percent is added for waste, as This Old House and Alexandria Moulding suggest. Allow more on a first attempt
  • Saw settings are for the molding laid flat on the saw, and they are starting points
  • Windows and bump-outs that break the run are not counted unless you add them as extra wall

Pro tips

  • Cope inside corners rather than mitering them, since a coped joint hides a corner that is out of true
  • Mark the wall at the bottom edge of the crown and work to that line
  • Keep a labelled test piece for each corner direction, right by the saw