Crown Molding: Counting Lengths for Mitre Cuts
Mitre cuts consume length at every corner, so a plain perimeter division undercounts. This post shows the allowance that covers them.
What is the Crown Molding Calculator?
Enter the total perimeter and the length of one molding piece, and the tool adds a 10 percent allowance for mitre cuts and mistakes before rounding up to whole pieces. The allowance is shown separately.
How to use it
- Measure the room perimeter in metres.
- Enter the length of one molding piece.
- Click Count Pieces.
Worked example
16 m at 3 m per piece needs 5.33 pieces exactly, or 5.87 with waste, rounded up to 6 pieces.
Why do mitres waste length?
Each angled cut removes a little material, and a miscut corner can cost a whole piece end.
Frequently asked questions
Should I buy one spare piece?
For rooms with many corners, yes. A spare piece is cheaper than a second trip.
Does ceiling height matter?
Not for the count, but taller profiles need more care at corners.