HesapHanem

Crown Molding Calculator

Estimate the crown molding length and standard 2.4 m pieces your room needs.

How it is calculated

The tool is for a rectangular room. Length and width are entered in centimetres. It finds the perimeter P = 2 × (length + width), adds a fixed 10 percent for waste, P_waste = P × 1.1, and divides by the length of one stick, 240 cm (2.4 m), rounding up: pieces = ceil(P_waste / 240). Perimeter and length with waste are displayed in metres with two decimals. Both dimensions must be above zero. The 10 percent is a flat allowance for mitre cuts and offcuts; it does not change for rooms with many corners, patterned molding or odd shapes, so add more for those. Pieces are counted as whole sticks, with no reuse of offcuts.

Worked example

A room is 420 cm by 350 cm. Perimeter: 2 × (420 + 350) = 1,540 cm = 15.40 m. With 10 percent waste: 1,540 × 1.1 = 1,694 cm = 16.94 m. Sticks of 240 cm: 1,694 / 240 = 7.06, rounded up to 8 pieces. Without the waste allowance the room would need 6.4 sticks (also 7), so the margin matters when the number is close to a whole stick.

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Common mistakes

  • Entering metres or feet where the fields expect centimetres; 4.2 gives a perimeter of a few centimetres.
  • Measuring the floor-to-floor outline rather than the wall lengths at ceiling height, where alcoves, bay windows or chimney breasts add extra length.
  • Using the tool for an L-shaped or other non-rectangular room; it assumes four straight walls, so sum the walls yourself.
  • Buying sticks of a different length (for example 3 m) and still using the piece count, which is based on 2.4 m sticks.
  • Assuming the waste figure covers a patterned or large-profile molding that needs matching at joints.

About this calculator

This calculator sums a room's wall perimeter to find the total linear length of crown molding needed, then adds a waste allowance — typically 10-15% — to cover the 45-degree miter cuts at each corner, which consume extra material and inevitably produce offcuts too short to reuse, before dividing the total by the standard stick length (8 feet, or 2.4 m) to give a shopping-list piece count.

Finish carpenters and general contractors use this waste-inclusive method when quoting jobs and ordering material, since underordering molding mid-project often means a second trip to the supplier with mismatched dye-lot batches, while DIY homeowners use it to buy the right number of sticks the first time.

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  • Editorial team

    The piece count comes from the total length, not wall by wall, so lay the cuts out on paper before buying. A wall of 2.6 m cannot be covered by one 2.4 m stick, and a short leftover piece from another wall may not fit. If the count lands just above a whole number, adding one stick is cheap insurance. What are the room's longest walls?

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