Crown Molding Calculator
How many pieces of crown molding
Adding crown molding? Enter the room perimeter to find the linear feet and number of pieces, with extra for miter cuts.
How to measure crown molding
Measure the ceiling perimeter, wall by wall, at the top of the wall rather than the floor. In a plain rectangular room that is 2 × (length + width), but measure each wall in anything with a chimney breast, an alcove or a bay, and do not deduct doorways — crown runs straight over them.
Then add more waste than you would for baseboard. This calculator defaults to 12% and 15% is defensible, because crown punishes mistakes in a way flat trim does not.
| Room | Perimeter | With 12% | 8 ft pieces | 12 ft pieces |
|---|---|---|---|---|
| 10 × 10 ft | 40 ft | 44.8 ft | 6 | 4 |
| 12 × 12 ft | 48 ft | 53.8 ft | 7 | 5 |
| 12 × 15 ft | 54 ft | 60.5 ft | 8 | 6 |
| 15 × 20 ft | 70 ft | 78.4 ft | 10 | 7 |
| 20 × 20 ft | 80 ft | 89.6 ft | 12 | 8 |
Crown molding spring angle and cut settings
Crown is sprung: it does not lie flat against either surface but bridges the corner at an angle, touching the wall along its bottom edge and the ceiling along its top. That single fact causes all the difficulty. A corner joint in crown is a compound cut — mitered and bevelled at once — because you are cutting a piece that sits in three dimensions.
The spring angle is how far the moulding leans back, and it is a property of the profile you bought. Most US crown is 38/52, meaning 38 degrees to the wall and 52 to the ceiling; 45/45 is the other common one. You need to know which you have before cutting anything.
| Spring angle | Miter | Bevel |
|---|---|---|
| 38° (most common) | 31.62° | 33.86° |
| 45° | 35.26° | 30.00° |
Those two numbers being marked on most miter saws as detents is not a coincidence — 31.6 and 33.9 exist on the scale precisely because 38-degree crown is so common. There is a simpler alternative: cut the moulding upside down and backwards, held against the saw fence at its spring angle, and you can use a plain 45-degree miter instead. Whichever method you choose, commit to it and label your offcuts, because mixing the two mid-room is how people end up with a pile of scrap.
Cope the inside corners
As with baseboard, coping beats mitering on inside corners, and it matters more here. Rooms are rarely square, ceilings are rarely flat, and a compound-mitered inside corner that is one degree out leaves a wedge-shaped gap at eye level where everyone can see it. A coped joint — one piece cut square into the corner, the second cut to follow its profile — closes tight at any angle and stays closed as the house moves.
Coping crown is genuinely difficult, which is the honest reason to buy 12 to 15% extra: the first two or three attempts become firewood. Outside corners have to be mitered, so measure the actual angle rather than assuming 90.
If that all sounds like more than you want to take on, pre-mitered corner blocks are a legitimate answer. They sit in each corner and let you butt straight, square-cut lengths into them — no compound cuts anywhere in the room. Purists dislike them; they also look considerably better than a badly coped corner.
Vaulted ceilings and non-90° corners
A vaulted or cathedral ceiling breaks the standard settings entirely, because the wall-to-ceiling angle is no longer 90 degrees. Two situations to distinguish:
- The sloped run itself needs moulding whose spring angle suits the slope, and the transitions at top and bottom are custom compound cuts.
- Where a sloped run meets a level one, the two pieces are different sizes in section and cannot simply be mitered together. This usually needs a transition block.
For anything vaulted, measure the actual wall-to-ceiling angle with a bevel gauge, cut generous test pieces from your waste allowance, and expect to iterate. It is the one crown job where hiring a trim carpenter is often cheaper than the material you will destroy learning.
Long runs, seams and crown molding installation cost calculator figures
Use the longest lengths you can get into the room to avoid mid-wall seams. Where a seam is unavoidable, join with a scarf cut — two opposing 45s that overlap — landed over a stud, rather than butting square.
| Item | Per linear ft | A 12 × 12 room (54 ft) |
|---|---|---|
| MDF or polystyrene | $1 to $4 | $54 to $216 |
| Pine, paint grade | $3 to $6 | $162 to $324 |
| Hardwood or ornate profile | $6 to $15 | $324 to $810 |
| Installation labour | $4 to $12 | $216 to $648 |
| Installed, painted MDF | $5 to $16 | $270 to $864 |
Labour is a larger share here than on any other trim, and that reflects the skill involved rather than the time. Prime and paint the lengths before installing, then fill nails and caulk both edges afterwards — crown almost always needs caulk along the top and bottom, because neither the wall nor the ceiling is truly straight. The baseboard calculator uses the same perimeter at the other end of the wall.
How this crown molding calculator works out its numbers
Piece counts are ceiling perimeter × (1 + waste) ÷ piece length, rounded up, for 8 ft and 12 ft stock with a 12% default waste allowance.
- 12% is higher than baseboard's 10% deliberately. Crown waste is dominated by failed compound and coped corner cuts rather than by ordinary offcuts, and beginners should use 15%.
- No door deduction. Crown runs continuously across the top of the wall, over every opening.
- Miter and bevel figures are the standard compound settings for 38° and 45° spring angles at a 90° corner. They do not apply to vaulted ceilings or out-of-square corners, which need the actual angle measured.
- Counts assume no joining of offcuts. In practice short pieces get reused, which is part of why the allowance is usually adequate.
- Not included: corner blocks, adhesive, nails, filler and caulk. Cost ranges are US planning figures gathered September 2026.
Reviewed September 2026.
Figures reviewed . Every worked example on this page is checked against the calculator above.
Crown Molding Calculator: frequently asked questions
How is crown molding measured?
By the ceiling perimeter, measured wall by wall at the top of the wall. For a plain rectangle that is 2 × (length + width). Do not deduct doorways, since crown runs straight over them, and add 12 to 15% for waste.
How much crown molding waste should I plan?
12 to 15%, more than any other trim. Corners need compound cuts that often need a second or third attempt, and a coped crown joint takes real practice — those failed attempts are the waste.
What are the miter and bevel settings for crown molding?
For the common 38° spring angle on a 90° corner, miter 31.62° and bevel 33.86°. For 45° spring, miter 35.26° and bevel 30°. Alternatively cut it upside down and backwards against the fence and use a plain 45° miter.
What is spring angle on crown molding?
How far the moulding leans back from the wall, a property of the profile itself. Most US crown is 38/52, meaning 38 degrees to the wall and 52 to the ceiling; 45/45 is the other common one. You need to know yours before cutting.
Should crown molding corners be coped or mitered?
Cope inside corners and miter outside ones. Rooms are rarely square and ceilings rarely flat, so a compound-mitered inside corner that is a degree out leaves a visible wedge at eye level. A coped joint closes tight at any angle.
How do you cut crown molding for a vaulted ceiling?
The standard settings do not apply, because the wall-to-ceiling angle is no longer 90 degrees. Measure the actual angle with a bevel gauge, cut test pieces from your waste, and use a transition block where a sloped run meets a level one.
Is crown molding hard to install?
It is the hardest common trim, because it sits sprung at an angle so every corner is a compound cut. Buy 12 to 15% extra for practice. Pre-mitered corner blocks are a legitimate shortcut that lets you butt square-cut lengths without any angled cuts.
How much does crown molding cost to install?
Roughly $5 to $16 per linear foot installed for painted MDF, so $270 to $864 for a 12 × 12 room. Labour is a bigger share than on other trim, which reflects the skill rather than the hours.