Insulation R-value, quantity & cost calculators

Free, no-signup insulation calculators for homeowners, DIYers and small contractors — figure out how much insulation to buy, what R-value an assembly delivers, and what a job should cost. Every tool runs on the measurements you take and the prices you enter, and shows its formula, a worked example and a reference table.

Insulation Calculators

The deterministic anchor: an R-value calculator (assembly R = sum of layers), an insulation thickness / required-R calculator, a U-value ↔ R-value converter, a batt bundle calculator, a blown-in bag calculator (coverage-per-bag or depth), a spray-foam board-feet & set calculator, a rigid-foam board/sheet calculator, a climate-zone target-R reference, and an insulation removal / add-over calculator.

R-value calculatorAdd insulation layers in series to get the total assembly R-value and U-value. Enter thickness and R per inch for each layer, add air films, done.Insulation thickness calculatorFind how many inches of insulation you need to reach a target R-value. Enter your target R and the material R per inch to get the required depth.U-value ↔ R-value converterConvert R-value to U-value and back in one step. U is thermal conductance, R is resistance, and they are exact reciprocals: U = 1 ÷ R and R = 1 ÷ U.Batt insulation calculatorWork out how many batt insulation bundles to buy. Enter the area and the coverage per bundle, add a waste allowance, and get the bundle count rounded up.Blown-in insulation calculatorCalculate how many bags of blown-in insulation you need. Choose the coverage-per-bag-at-R chart or the depth (board-feet) method for your attic square footage.Spray-foam board-feet & set calculatorCalculate spray foam board-feet and how many kits or sets you need. Board-feet = area × thickness; sets = board-feet ÷ the labeled yield per kit, rounded up.Rigid-foam board / sheet calculatorCount the exact 4×8 rigid foam sheets your area needs and get the board R-value for EPS, XPS or polyiso, from thickness × R per inch. Free tool.Climate-zone target-R referenceLook up the target R-value for your IECC climate zone and assembly. Typical attic, wall-cavity and floor R-value bands for zones 1 through 8.Insulation removal / add-over calculatorSee how much insulation to add over existing to reach a target R-value. Added depth = (target R − existing R) ÷ R per inch, with the new total R.

Cost Estimators

Budget the job: insulation cost per square foot, installation cost, cost by R-value, labor cost, removal & replacement cost, and an insulation-contractor quote check — on the prices you enter from your own quotes.

Insulation cost per square footWork out insulation cost per square foot from your area and your quoted $/ft2. Free calculator with the formula, a worked example and labeled per-foot bands.Insulation installation costEstimate a full insulation installation: material, labor, air-sealing, removal, access and a contingency. Free itemized calculator with formula and example.Insulation cost by R-valueEstimate insulation cost by target R-value: choose R-30 to R-60, enter your $/ft2 and get the total. Free calculator with labeled per-R bands, example and FAQs.Insulation labor costEstimate insulation labor cost by area ($/ft2) or by the bag ($/bag installed). Free calculator with both methods, a worked example and FAQs.Insulation removal & replacement costEstimate insulation removal and replacement cost: demolition $/ft2 plus haul, then new insulation $/ft2. Free calculator with formula, worked example and FAQs.Insulation contractor quote checkSanity-check an insulation quote: divide the bid by the area for a $/ft2 and compare it to the labeled band for the material. Free checker with an example.

Spray Foam

The spray-foam cluster: spray foam insulation cost, an open- vs closed-cell board-feet compare, a spray-foam set / kit quantity, and spray foam attic / wall cost.

Spray foam insulation costPrice a spray foam job from board-feet and your own $/board-foot: material, labor and a contingency cushion, with labeled installed bands as a sanity check.Open- vs closed-cell compareCompare open- and closed-cell spray foam for a target R: the depth each needs, the board-feet and the cost side by side, so you order the right foam.Spray foam set / kit calculatorWork out how many DIY spray foam kits or sets you need from your board-feet and the kit yield — whole kits only, with a margin for cold cans and overspray.Spray foam attic / wall costEstimate a spray foam attic or wall job from area and your quoted $/ft², plus a contingency cushion — the fast way to sanity-check a per-square-foot quote.

Attic & Roof

Attic and roofline: attic insulation cost, an attic bag / depth calculator to a target R, a blown-in vs batt attic compare, attic R-value by climate zone, and a cathedral / roofline insulation quantity.

Attic insulation costEstimate attic insulation cost from your square footage and your own installed price per ft². Adds a contingency buffer and labeled installed price bands.Attic bag / depth calculatorFind how many bags of blown-in insulation your attic needs to hit a target R-value, and how deep to blow it, using the labeled coverage-per-bag chart.Blown-in vs batt attic compareCompare blown-in bags vs batt bundles for an attic, side by side, with your own $/bag and $/bundle for the cost columns. Free, no signup, transparent formula.Attic R-value by climate zoneLook up the labeled IECC / ENERGY STAR attic target R-value for your U.S. climate zone (R-30 to R-60) before you size bags, depth or cost. A free reference.Cathedral / roofline insulationSize cathedral / roofline insulation: the R-value a rafter cavity holds, the spray-foam board-feet, and the number of kits to buy. Transparent formula.

Wall, Floor, Crawlspace & Basement

THERMAL insulation of walls, floors and below-grade: a wall insulation calculator, floor / crawlspace insulation cost, a rim-joist insulation quantity, basement-wall thermal insulation cost & R, and a garage wall/ceiling quantity.

Wall insulation calculatorFind how many batt bundles a wall needs from its length, height and openings, plus the cavity R-value. Transparent formula, worked example, free, no signup.Floor / crawlspace insulation costEstimate floor or crawlspace insulation cost from your area and your own installed price per square foot, with a contingency buffer. Thermal only, free.Rim-joist insulation calculatorSize rim-joist insulation: the rim-joist area, spray-foam board-feet and kits, or rigid-foam pieces cut to the bays. Transparent formula, worked example, free.Basement-wall thermal insulation cost & REstimate basement-wall thermal insulation cost from your wall dimensions and price per ft², plus the assembly R from rigid and cavity layers. Thermal only.Garage wall/ceiling insulationSize garage insulation fast: enter wall and ceiling areas to get the batt bundles to buy, with the formula shown and a worked example. Free tool.

Materials & Savings

Compare and plan: fiberglass vs cellulose vs mineral wool, a rigid-foam (EPS/XPS/polyiso) R & sheet calculator, an R/inch by material reference, an energy-savings / simple-payback estimator, and a sound / acoustic insulation quantity.

Fiberglass vs cellulose vs mineral woolCompare fiberglass, cellulose and mineral wool for a target R-value: the depth each needs and your own cost columns, so you order the right insulation.Rigid foam R & sheet calculatorGet the R-value and 4x8 sheet count for rigid foam board (EPS, XPS or polyiso) from thickness, R per inch and area, so you buy enough sheets the first time.R/inch by material referenceLook up the labeled R-value per inch for fiberglass, cellulose, mineral wool and foam, plus the inches each one needs to hit the common R-38 and R-49 targets.Energy-savings / payback estimatorEstimate the rough annual savings and simple payback of adding insulation from your own heating bill: a relative heat-loss index, not an energy audit.Sound / acoustic insulationWork out how many batt bundles you need to sound-insulate an interior wall from the area and coverage per bundle, rounded up to whole bundles.
Planning estimate: this is a planning estimate from the numbers you enter — not a bid or a contract. Insulation pricing depends on material, R-value, access, prep, air-sealing, removal and local labor. Get itemized written quotes from licensed, insured insulation contractors before you commit.
Confirm coverage-per-bag, R-per-inch and set yield against the exact product you buy and order a little extra (~5–10%) for framing, gaps and settling. Coverage, R/inch and set yields vary by product and brand — read the bag/kit and the data sheet.

The R-value-per-inch reference

Our own cross-material reference: R-per-inch for every common insulation, with the inches of material each one needs to hit R-30, R-38 and R-49 and a labeled installed cost band — one neutral table instead of a dozen single-brand coverage widgets. See how it’s built in the methodology.

Open the R/inch reference →

Built for the whole insulation project — and to stay correct forever

InsulationCalcs gathers the calculations homeowners, DIYers and small contractors reach for when insulation is going in — how much material to buy (batt bundles, blown-in bags to a target depth or R, spray-foam board-feet and kits, rigid-foam sheets), what R-value an assembly delivers or how thick a material must be to hit a target R, which climate-zone R to aim for, and what a job costs — R-value → quantity → cost → material/area, in one focused hub, in US units, without signup, with transparent formulas. Every tool shows not just the answer but the underlying formula, a worked example and a reference table, so you can sanity-check an insulation contractor’s quote.

Because the tools rest on timeless building physics (thermal resistance adds in series: R = Σ thickness × R/inch; U = 1 ÷ R; required thickness = target R ÷ R/inch; bags = ceil(area ÷ coverage) or ceil(area × depth ÷ bag yield); board-feet = area × thickness; sets = ceil(board-feet ÷ yield); sheets = ceil(area ÷ 32); cost = quantity × your $/unit + labor + add-ons − discount, ×(1 + contingency)) and stable, labeled conventions (R/inch by material, IECC climate-zone target R, coverage-per-bag, batt coverage, set yields, waste ~5–10%), they stay correct with no maintenance — no live material or labor price list, no regional cost index, no product catalog, no contractor directory. Cost tools use the prices you enter from your own quotes and bills; labeled cost bands are only a sanity guide. More at Sources & formulas, Methodology and About.

Estimates, not bids. Every result is a planning estimate from your own prices, or a material-quantity / R-value guide — not a bid, an install procedure, or structural, fire-code, vapor-barrier, HVAC or energy-audit design. Get itemized written quotes from licensed, insured insulation contractors; confirm coverage-per-bag, R/inch and set yield against the exact product and order a little extra (~5–10%) for framing, gaps and settling; and follow the product data sheet and your local energy code.