Coffered ceiling trim calculator
Ceiling size and coffer grid: you get interior and perimeter beam footage, trim for both sides and the number of pieces.
Purchase quantity
118.11 ft
Net measurement: 118.11 ft · Waste 15 %
- Interior beams59.055 ft
- Perimeter beam59.055 ft
- Trim (two sides per beam + perimeter)203.74 ft
- Molding pieces26 pc
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How it's calculated (visible formula)
beams = (coffers along − 1) × width + (coffers across − 1) × length; trim = (2 × beams + perimeter) × (1 + waste)
- Net geometric measurement, no waste.
- Adjustable waste % for cuts and breakage.
- Purchase rounded up to sellable units (boxes, bags, buckets, boards).
How to calculate it, step by step
- Measure ceiling length and width.
- Choose the coffer grid (e.g., 3 × 3).
- Work out interior and perimeter beam footage.
- Multiply by two faces of trim and add the perimeter.
- Add 15% waste and round up to pieces.
Worked example: 16 × 13 ft ceiling, 3 × 3 coffers
- Beams: 2 × 13 + 2 × 16 = 58 ft
- Perimeter: 58 ft
- Trim: (116 + 58) × 1.15 ≈ 200 ft
→ About 25 pieces of 8 ft trim.
Common mistakes
- Uneven coffers from laying out off a wall.
- Too little waste — miters eat material.
- Not finding joists to fix beams to.
Pro tips
- Lay out from the ceiling center so coffers are symmetric.
- Build beams on the floor and lift them assembled when possible.
- Fasten beams to joists or blocking, never just drywall.
- Fill and sand joints before painting.
From calculation to quote
Add labor, overhead and your margin, and generate the professional PDF.
FAQs
- How much waste for trim?
- 15% because of all the miters.
- How do I lay out coffers?
- From the ceiling center out, so they're symmetric.
- What are the beams made of?
- MDF or wood boxes fixed to blocking or nailers.
- Minimum ceiling height for coffers?
- About 9 ft so the room doesn't feel cramped.
- How deep are coffer beams?
- 4–8 in depending on ceiling height.
- Can coffers have lighting?
- Yes — hidden LED strips in the beams or a recessed light per coffer.
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.