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Crown Molding Calculator

A crown molding calculator works out how much crown you need — in linear feet and pieces — from the room's perimeter, with a generous waste allowance for the tricky corner cuts. Unlike baseboard, crown runs unbroken around the whole ceiling, so doors and windows don't reduce it.

Your measurements

Result

Crown wastes more than other trim because every corner is a compound mitre or coped joint, and a spoiled cut costs a length. This sizes the order with that built in.

How it is calculated

Perimeter = 2 × (length + width), or your entered figure — crown runs the full ceiling line with no deductions. Pieces = perimeter × waste multiplier ÷ stock length. The 15%+ allowance covers the compound mitre and cope cuts at corners, which spoil more material than flat trim.

Steps

Enter the room length and width, or the perimeter.
Choose your stock length (8 ft typical).
Use a higher waste allowance — 15% or more.
Read the linear feet and number of pieces.
Cope inside corners rather than mitring for tight joints.

Worked example

A 14 × 12 ft room has a 52 ft perimeter — about 60 ft with 15% waste, or eight 8 ft pieces of crown molding.

Common questions

How much crown molding do I need?

The full room perimeter, plus extra for corners. A 14 × 12 ft room needs about 60 ft with waste — crown isn't reduced for doors or windows.

Why more waste than baseboard?

Crown's corners are compound mitre or coped cuts that ruin more offcuts, so 15%+ waste is sensible versus ~10% for baseboard.

Should I cope or mitre crown corners?

Cope inside corners for a tight joint that resists gaps as the house moves; mitre outside corners. Practice cuts on offcuts first.

Does crown molding go around the whole room?

Yes — it runs the entire ceiling perimeter without breaks for doors or windows, unlike baseboard.