Crown Molding Calculator
Estimate how much crown molding you need for any room. Enter wall lengths or room perimeter, choose your trim piece length, and get an accurate count with waste factor built in — plus inside and outside corner counts.
Enter Your Measurements
Full Breakdown
Room Perimeter
Linear Feet (with waste)
Pieces Needed
Inside Corners
Outside Corners
Estimated Cost
How to Use This Calculator
- Enter room dimensions or the total perimeter in linear feet.
- Select the piece length your trim comes in (most common: 8' or 12').
- Set a waste factor — 10% is standard for miter cuts and mistakes.
- Enter the number of inside and outside corners in the room.
- Click "Calculate Crown Molding" for your material list.
The Formula
Perimeter = 2 × (Length + Width)
For rectangular rooms. For irregular rooms, measure each wall and add them up.
Linear Feet Needed = Perimeter × (1 + Waste%/100)
Pieces = ⌈Linear Feet ÷ Piece Length⌉
Always round up to whole pieces. Standard waste factor is 10% to account for miter cuts, coping, and off-cuts.