Crown Molding Quantity Calculator

How it works

Crown molding runs along the line where the walls meet the ceiling, so the length needed is the ceiling perimeter: twice the length plus twice the width for a rectangular room. Unlike baseboard, crown does not stop at doorways.

A waste allowance (10% by default, a typical figure and editable) covers the offcuts at corners and joints; the run with waste is divided by the stock length and rounded up to whole lengths.

Each corner consumes part of a length, and an outside corner takes two pieces mitered to meet at a point that projects into the room. By default this calculator adds one extra length for every four outside corners, or part of four, on top of the waste allowance; that is this calculator's own rule, editable, and 0 turns it off. Inside and outside corners together give the number of corner joints to cut. The miter and bevel angles for crown at a corner are in the Compound Miter Calculator.

Formula

perimeter      = 2 × (length + width)   (or as entered)
with waste     = perimeter × (1 + waste % ÷ 100)
run lengths    = with waste ÷ stock length, rounded up
corner lengths = outside corners ÷ corners per extra length (default 4), rounded up; 0 if set to 0
total lengths  = run lengths + corner lengths
corner joints  = inside corners + outside corners
cost           = total lengths × stock length × price per ft

Example

A 14 × 12 ft room has a 52 ft ceiling perimeter, 57.2 ft with 10% waste. In 16 ft lengths that is 57.2 ÷ 16 = 3.58, so 4 lengths.

With four inside corners and no outside corners there is no corner allowance: 4 lengths and 4 corner joints, which at $3.00 a foot is 4 × 16 × $3.00 = $192.00.

Assumptions and limitations

• Lengths are pooled: offcuts from one wall are counted toward the next. A wall longer than the stock length needs a scarf joint, and short pieces between corners can leave offcuts too short to reuse.
• The one-length-per-four-outside-corners allowance and the 10% waste are rules of this calculator, not manufacturer figures; both are editable and the allowance is shown separately in the result.
• The ceiling perimeter is taken as entered; a sloped or vaulted ceiling, where crown follows a rake, is not modelled.
• The price is an illustrative default and editable.

Frequently asked questions