How much extra crown should I buy?

10% for rectangular rooms; 15% with many corners.

How do I cut inside corners?

Cope them, or miter with the molding upside-down and nested in the saw.

Wood or polyurethane?

Polyurethane is light and flexible; wood is paint- or stain-grade.

How do I cut crown molding?

On a miter saw, upside-down and nested, or flat with compound angles.

Construction adhesive plus brad nails to hold while it sets.

What size crown for my ceiling?

Bigger for taller ceilings: 3–4 in for 8 ft, 5–6 in for 9–10 ft.

Crown molding calculator

Room perimeter, corners and piece length: you get crown molding pieces, miter cuts and tubes of adhesive.

Purchase quantity

64.961 ft

Net measurement: 59.055 ft · Waste 10 %

Molding pieces9 pc
Miter cuts8 unit
Construction adhesive (1 tube per 26 ft)3 tube

Use my prices

Your prices per language/currency. Used when you enable “Use my prices” in calculators. My prices →

Calculate labour, margin & GST

How it's calculated (visible formula)

pieces = ceil(perimeter × (1 + waste) ÷ piece length); miters = 2 × corners

Net geometric measurement, no waste.
Adjustable waste % for cuts and breakage.
Purchase rounded up to sellable units (boxes, bags, buckets, boards).

See methodology and formula versions

How to calculate it, step by step

Measure the room perimeter.
Count inside and outside corners.
Add 10–15% for miters and splices.
Divide by piece length and round up.
Work out adhesive and caulk.

Worked example: Room with 59 ft perimeter, 4 corners

59 × 1.10 ≈ 65 ft
65 ÷ 8 ft ≈ 8.1 → 9 pieces
8 miters

→ 9 pieces of 8 ft and 3 tubes of adhesive.

Common mistakes

No waste for miters and scarf joints.
Cutting crown flat instead of nested.
Joining pieces mid-wall in plain view.

Pro tips

Cut crown upside-down and nested against the saw fence.
Cope inside corners for a tighter fit than miters.
Scarf joints at 45° away from the main sightline.
Caulk joints before painting.

From calculation to quote

Add labour, overhead and your margin, and generate the professional PDF.

Create quote Calculate margin & GST

FAQs

How much extra crown should I buy?: 10% for rectangular rooms; 15% with many corners.
How do I cut inside corners?: Cope them, or miter with the molding upside-down and nested in the saw.
Wood or polyurethane?: Polyurethane is light and flexible; wood is paint- or stain-grade.
How do I cut crown molding?: On a miter saw, upside-down and nested, or flat with compound angles.
Nails or adhesive?: Construction adhesive plus brad nails to hold while it sets.
What size crown for my ceiling?: Bigger for taller ceilings: 3–4 in for 8 ft, 5–6 in for 9–10 ft.

Sources and standards

Maintained by Srikanta M · Formula v1.0.0 · Verified 2026-09-10 · Updated 2026-09-10 · Limits: quantity estimation, not structural design or site supervision.