Rigid Foam Board Calculator
Foam board is sold by the sheet, usually 4×8. Enter the area you're covering and this returns sheets, layers, R-value and cost for each foam type.
Your project
Covers cuts, compression and odd bays. 10% is the usual default.
Your results
- Coverage to buy
- 880 sq ft
- Sheets required
- 28 sheets
- R-value per layer
- R-12
- Seam tape needed
- 336 ft
- Material cost
- $845
- Cost per sq ft
- $0.96
32 sq ft per sheet
Estimates use typical US material and labor pricing. Confirm quantities against the coverage chart on the bag before you buy.
Gear for this job
Rigid Foam Board Insulation
Multi Purpose XPS Foam Board,2 Pack 15.6x11.7X 2in Polystyrene Craft Foam Sheets,Rigid and Easy to Shape,DIY Modeling Art Projects, Party Decoration, Cosplay Prop Production, Carve,Heat Insulation
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Double-Layer Insulated Foam Panels, 3-Pack Insulation Seal Panels for Portable AC Window Vent Seal Kit, Thick Adjustable Insulation Board, Air Conditioner Window Gap Filler
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GCGOODS Window Air Conditioner Insulated Foam Panels, Winter Surround Insulation Side Panel with Top Seal Strip for Window AC Unit Indoor, White
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Foam Board Insulation Panels 2 Inch
Multi Purpose XPS Foam Board,2 Pack 15.6x11.7X 2in Polystyrene Craft Foam Sheets,Rigid and Easy to Shape,DIY Modeling Art Projects, Party Decoration, Cosplay Prop Production, Carve,Heat Insulation
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LuckyFoam Blue 4 Pack 15x12x2 inch Foam Sheets 2 Inch Thick | Polystyrene Rectangles XPS Foam Board Craft for Insulating DIY Modeling Art Supplies
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Fabbay 2 Pcs Pink XPS Foam Board 15" X 12" 2" Thick Rectangle Craft | Polystyrene Foam for Insulation, Modeling Art Supplies, Lightweight Pink Boards, Easy to Cut and Shape for DIY Projects
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House Wrap Insulation Tape
XFasten Foam Pipe Insulation Tape 2 Inch x 15 Feet Heavy-Duty AC Line Insulation Outdoor Pipe Wrap Tape AC Pipe Insulation Outdoor Pipe Insulation Wrap Tape HVAC Line Insulation Pipe Wrap Around Tape
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Vapor Barrier Tape 4" x180' 1 Roll Waterproof Seam Tape | White polyethylene tape for crawl spaces & moisture barriers, waterproof seam tape for underlayments, insulation & liners
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BlueTex Insulationㅤ 4'' Wide x 180' Long White Vapor Barrier Tape - 1 Roll, Waterproofing for Stucco, Crawlspaces, Repair, Underlayment Seams, Metal Building Seams, Excellent Air Barrier
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How this calculator works
- Coverage = area × (1 + waste %)
- Sheets = coverage ÷ (sheet width × sheet length), rounded up
- R per layer = R-per-inch × board thickness
Frequently asked questions
EPS, XPS or polyiso — which foam board is best?
Polyiso gives the most R per inch (about R-6) and suits above-grade walls and roofs. XPS (R-5) handles moisture best and is the usual pick below grade. EPS (R-3.9) is cheapest and fine under slabs.
Do foam board seams need taping?
Yes if the foam doubles as your air barrier. Tape every seam and seal the edges with canned foam — untaped board can lose most of its air-sealing benefit.
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Coverage to buy
880 sq ft