Crown Molding Calculator — Free Online Tool
Crown molding is the jewelry of a room — and the most cut-waste-heavy trim you'll install. This crown molding calculator converts your ceiling perimeter into linear feet with a 15% allowance for the tricky compound cuts.
What is the Crown Molding Calculator?
Every room needs its full ceiling perimeter in molding, and every corner needs a compound miter cut — the #1 source of wasted pieces for beginners. The 15% waste factor assumes you're learning; pros who cope their joints can sometimes get away with 10%.
Size the molding to the ceiling height: 3–4 inch molding for 8-foot ceilings, 5–7 inch for 9–10 foot, larger for grand rooms. Paint-grade MDF or polyurethane is cheaper and won't split like wood. This crown molding calculator gives linear feet; crown is sold in 8–16 ft lengths, so divide and round up for your board count.
How to use this calculator
- Measure the ceiling perimeter of the room.
- Enter it and click Calculate Crown Molding.
- Choose molding size to match your ceiling height.
- Practice compound cuts on scrap before touching the good stock.
Formula
Frequently asked questions
What size crown molding for 8-foot ceilings?
3–4 inches. Bigger molding overwhelms standard ceilings; this crown molding calculator just handles the quantity.
Should I cope or miter inside corners?
Cope inside corners — the joint stays tight even as wood moves seasonally.
Do I paint crown molding before installing?
Prime first, install, caulk the gaps, then apply the final coat for the cleanest lines.
How is crown molding attached?
Brad nails into studs and top plates, plus construction adhesive — never nails into drywall alone.