Calculate how much crown molding you need from room size, wall lengths, or perimeter, including cutting waste, sticks to buy, and material cost.
Crown Molding Length Formula
L = P * (1 + W/100)
P = 2*(RL + RW)
N = ceil(L / S)
- L is the perimeter plus waste allowance, before rounding to stock (ft or m)
- P is the ceiling perimeter (ft or m)
- W is the cutting waste percentage (%)
- RL and RW are the room length and width (ft or m)
- N is the number of sticks to buy, rounded up
- S is the length of one stick as sold (ft or m)
The calculator finds the ceiling perimeter in one of three ways. If you enter a room length and width, it uses the rectangle formula P = 2*(RL + RW). If your room is not a simple rectangle, you can enter each wall length individually and the calculator sums them. If you already know the perimeter, you can enter it directly. In every mode the perimeter is multiplied by the waste factor to get the total length to buy, and that length is divided by the stick length and rounded up to get the number of pieces. The advanced options add a material cost estimate from a price per stick or per foot, count the angled corner cuts you will make from your inside and outside corner counts, and show an illustrative crown-size style guide for your ceiling height. Stick counts are total-length lower bounds, not a cutting optimisation; joints, kerf and offcut usability can require more stock.
Illustrative Crown Size by Ceiling Height
Buying the right length is only half the decision. Crown that is too small looks lost on a tall wall, and oversized crown crowds a low ceiling. The ranges below are the article’s illustrative style guide, not dimensional requirements. Compare actual profile rise and projection with your room and any obstructions.
| Ceiling height | Crown height range | Notes |
|---|---|---|
| 8 ft | 3 to 5-3/4 in | Stay near the low end in small rooms |
| 9 ft | 4-1/4 to 7 in | The most flexible height for standard profiles |
| 10 ft | 5 to 8 in | Larger profiles read as intentional, not bulky |
| 11 ft and up | 8 in or larger | Consider a built-up, multi-piece crown |
The following illustrative USD price ranges are example budgeting inputs, not verified current quotes. Enter a supplier’s actual material price; installation, tax and delivery are excluded.
| Material | Illustrative price per linear foot | Best for |
|---|---|---|
| MDF | $1 to $4 | Painted crown on a budget |
| Pine and softwood | $2 to $6 | Paint or light stain, easy to cut |
| Polyurethane foam | $2 to $6 | Moisture-prone rooms, lightweight installs |
| Hardwood (oak, maple) | $5 to $15 | Stain-grade, high-end finish work |
Example Problems
Example 1: A rectangular living room measures 16 ft by 12 ft, and crown is sold in 8 ft sticks. The perimeter is P = 2*(16 + 12) = 56 ft. With an assumed 15% waste factor, L = 56 * 1.15 = 64.4 ft. The number of sticks is N = ceil(64.4 / 8) = 9, so you would buy 9 sticks, or 72 ft of material.
Example 2: An L-shaped kitchen has six walls measuring 14, 10, 6, 4, 8, and 14 ft. The perimeter is the sum, 56 ft. The room has an extra corner pair, so you choose 20% waste: L = 56 * 1.20 = 67.2 ft. Using 16 ft sticks, N = ceil(67.2 / 16) = 5 sticks, which gives 80 ft purchased and about 12.8 ft of spare material for miscuts on the compound miters.
Crown Molding Length FAQ
Do you subtract doors and windows when measuring for crown molding? For an ordinary opening below the ceiling joint, do not subtract it: crown continues above it. Subtract or alter runs where a ceiling-height opening, architrave or other obstruction actually interrupts the crown. Measure the full length of every wall at ceiling level and use the total. This is the opposite of baseboard, where you do subtract door openings.
Why buy longer sticks than the calculator's minimum? Every joint in the middle of a wall is a scarf joint that must be cut, glued, and sanded, and it can open up as the wood moves seasonally. If a wall is 14 ft and you only have 8 ft sticks, you are forced to joint mid-wall. Buying 16 ft sticks lets each wall be a single piece, which looks better and installs faster, even if it slightly increases leftover material.
What waste percentage should you use? Set waste to suit your cuts, experience and supplier guidance. Metrie suggests considering an extra 10%; this calculator starts at an adjustable 15% planning allowance. No percentage guarantees a sufficient cut plan. Inside corners consume material because each coped or mitered end needs extra length to cut, and a single miscut on an 8 ft stick can scrap the whole piece.
