Spray foam yield calculator
Foam type, area, thickness, kit yield and real-world yield: you get volume, board feet, kits needed and resulting thermal resistance.
Purchase quantity
3.27 yd³
Net measurement: 3.27 yd³
- Spray foam kits3 unit
- Board feet of foam1059.44 bd ft
- Resulting thermal resistance (RSI)2.08 m²K/W
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How it's calculated (visible formula)
board feet = area (sq ft) × thickness (in); kits = ceil(bd ft ÷ real yield ÷ kit bd ft); RSI = thickness ÷ λ
- 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 the area to spray.
- Pick thickness for the target R-value.
- Work out board feet.
- Apply the kit's real-world yield.
- Round up to full kits and check the final R.
Worked example: 540 sq ft at 2 in closed cell, 600 bd ft kits
- ≈ 1,059 bd ft
- 1,059 ÷ 0.85 ≈ 1,246 ÷ 600
→ 3 kits; RSI 2.08 (≈ R-12).
Common mistakes
- Using nominal kit yield.
- Spraying on cold or damp surfaces.
- Closed-cell passes thicker than 2 in.
Pro tips
- Warm components to the maker's temperature before spraying.
- Spray in lifts — about 2 in per pass for closed cell.
- Use respiratory protection and ventilate.
- Protect foam from UV and, indoors, with a thermal barrier.
From calculation to quote
Add labor, overhead and your margin, and generate the professional PDF.
FAQs
- What is a board foot of spray foam?
- 1 sq ft at 1 in thick.
- Closed or open cell?
- Closed cell gives about R-6.5 per inch and is a vapor retarder; open cell about R-3.7 per inch.
- Real yield of a kit?
- About 80–90% of the label depending on temperature and technique.
- Open or closed cell in an attic?
- Closed cell for a vapor retarder and more R per inch; open cell for sound and lower cost.
- How far does a 600 bd ft kit go?
- 600 sq ft at 1 in in theory; 80–90% in practice.
- Do I need a separate vapor barrier?
- Closed cell acts as one; open cell may need one in cold climates.
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.