Vaulted ceiling area calculator
Length, width, pitch and ceiling type (cathedral or shed): you get the true sloped area, gable wall area and peak height — for paint, insulation or paneling.
Sloped area
34.64 m²
- Sloped ceiling area34.64 m²
- Floor plan area30 m²
- Gable walls (triangles)7.22 m²
- Peak height above wall top1.44 m
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How it's calculated (visible formula)
sloped = plan ÷ cos(pitch); rise = (width ÷ 2 for cathedral, width for shed) × tan(pitch)
- 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 room length and width in plan.
- Measure ceiling pitch (digital level or rise ÷ run).
- Choose cathedral or shed.
- Divide plan area by the cosine of the pitch.
- Work out gable areas for paint or paneling.
Worked example: 20 × 16 ft room, cathedral at 30° (7/12)
- Plan: 320 sq ft
- 320 ÷ cos 30° ≈ 370 sq ft
- Rise: 8 × tan 30° ≈ 4.6 ft
→ About 370 sq ft of ceiling and 74 sq ft of gables.
Common mistakes
- Painting or insulating from floor area.
- Forgetting gables when estimating paint.
- Measuring pitch on the overhang.
Pro tips
- Use sloped area for paint, insulation and planks; plan area only for flooring.
- Price scaffolding or a lift to paint tall ceilings.
- Insulate well — vaulted ceilings lose a lot of heat.
- Run a ceiling fan to push warm air back down.
From calculation to quote
Add labour, overhead and your margin, and generate the professional PDF.
FAQs
- How much area does pitch add?
- About 15% at 30° and 41% at 45° (12/12).
- What is a gable wall?
- The triangular wall under a cathedral ceiling.
- How do I measure ceiling pitch?
- With a digital level, or rise over run.
- How do I measure a ceiling with several slopes?
- Work out each plane separately and add them.
- What is the pitch factor?
- 1 ÷ cos(pitch) — what multiplies the plan area.
- How much paint for a vaulted ceiling?
- Get the area here and take it to the paint calculator.
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.