How much is blown-in insulation per square foot?

Material alone, at retail shelf price, is $0.99 per square foot at R-30, $1.71 at R-49 and $2.13 at R-60, computed from one named product's published price and coverage. Installed, the model on this site adds a labour line of $0.47 to $0.95 per square foot, giving $1.46 to $1.93 at R-30 and $2.18 to $2.66 at R-49. The labour side rests on a burden multiplier and a crew-hour figure that are estimates, not measurements.

How much does one bag of blown-in insulation cover, and what does it cost?

The measured anchor this site carries is Owens Corning AttiCat blown-in fibreglass, 27.5 lb bag at $67.58, a retail price read on the date in the sources note. Its published coverage is 110.7 square feet at R-19, 68.5 at R-30 and 39.5 at R-49. Coverage is the number that matters, not the price: one bag buys less area the deeper you go, so 1,000 square feet takes 15 whole bags at R-30 and 32 at R-60. Every product differs and its own bag label is the authority.

Why is a per-bag installed price higher at R-30 than at R-60?

Because a bag covers more floor at R-30, so more of the labour line rides on each one. In this model labour scales with floor area and not with depth, at $0.47 to $0.95 per square foot, while material is a flat $67.58 a bag. That puts the installed cost of a bag at roughly $100 to $132 at R-30 and $83 to $98 at R-60. The labour side of those rests on a burden multiplier and a crew-hour figure that are estimates, not measurements. Two per-bag quotes at different targets cannot be compared at all until both are converted to a per-square-foot figure.

What is the do-it-yourself saving on blown-in insulation, in dollars?

Smaller than the headline suggests, because material dominates the job. On a 1,200 square foot attic to R-49, 31 bags at retail is $2,095, against a modelled installed $2,600 to $3,200, whose labour side rests on a burden multiplier and a crew-hour figure that are estimates rather than measurements. The whole prize is $505 to $1,105, or 19 to 35 percent, and out of it come the blower rental, a fitted respirator, eye protection, gloves, baffles, depth markers and the trips. Price those locally before deciding. You also buy material at the same retail price a contractor buys below.

Why does doubling the R-value cost more than double in material?

Loose-fill compresses under its own weight, so a deeper layer is a denser layer and yields less R per inch than a shallow one. The manufacturer's own chart shows it: R times coverage per bag falls as the labelled R rises. Going from R-30 to R-60 doubles the target but multiplies retail material cost per square foot by about 2.2. Halving the R-30 coverage to get an R-60 figure predicts 34.3 square feet per bag where the manufacturer publishes 31.8, so an order built on the shortcut lands about 7 percent short of the bags the job needs.

Does blown cellulose cost less than blown fibreglass?

R per inch cannot answer that. Cellulose runs R-3.2 to R-3.8 per inch against fibreglass at R-2.2 to R-2.7, so it reaches a target in less depth, but the cost of a blown job is bags rather than inches, and bags come from a product's own coverage chart, bag weight and settled density. A denser material that needs fewer inches can still need more material by weight. To price a cellulose job, take the bag price and the published coverage at your target R-value from the specific product being quoted and run the same two steps as the table on this page: floor area divided by coverage gives bags, bags times bag price gives material. The figures here are for one fibreglass product and do not price cellulose.

How many bags do I need for a 1,000 square foot attic?

For the anchor product, 15 whole bags at R-30, 19 at R-38, 26 at R-49 and 32 at R-60, each rounded up from the exact coverage figure because bags are sold whole. R-30 and R-49 sit on the manufacturer's published coverage points; R-38 and R-60 are interpolated between and beyond them. Round up rather than down, because a hopper left short at the far corner of an attic costs a second trip. The bag label of the product actually blown is the authority over any table.

Blown-in insulation cost, per square foot and per bag

By Insulation Report Editorial. Last reviewed August 2026. How we research this.

Blown-in attic insulation is quoted three ways, and they are the same number wearing different clothes. Per square foot of attic floor, the model on this page puts fibreglass at $2.18 to $2.66 installed at R-49 and $2.60 to $3.07 at R-60. Per bag, the same job is $86 to $105 at R-49, because one bag of the anchor product covers 39.5 square feet at that target. Material alone, at retail shelf price, is $1.71 per square foot at R-49, which is most of the total. Convert between them with one identity: installed price per bag equals installed price per square foot times the square feet one bag covers at your target R-value. Coverage falls as the target rises, so a per-bag price is meaningless until the R-value is stated. Two inputs behind these figures, the burden multiplier and the crew hours, are estimates rather than measurements.

The three ways this job gets quoted

The attic insulation cost hub builds the installed total by attic size and target, states the four inputs behind it, and gives a test for whether a quote is fair. This page works one level below that, at the unit: what a bag covers, what a bag costs, and how a price expressed in any one of the three common units converts into the other two.

Contractors and retailers do not agree on a unit. A bid arrives as a flat project price. A supplier prices by the bag. Cost content quotes dollars per square foot. All three describe the same job, and two pieces of arithmetic move between them.

Quoted as	What it is measuring	To get dollars per square foot
Per square foot	Attic floor area, which is roughly the footprint of the heated space below, not the roof area	Already there. Check which area the contractor measured
Per bag installed	One package of loose fibre, delivered and blown	Divide by the square feet one bag covers at the target R-value
Flat project price	Everything in the written scope, which may or may not include air sealing, baffles and disposal	Divide by the attic floor area in the scope

The identity worth memorising runs the other way, because it is the one that catches a bad comparison: installed price per bag equals installed price per square foot times the coverage of one bag at that R-value. Coverage is a published property of the product, so both sides are checkable.

The conversion, worked

Take a 1,200 square foot attic blown to R-49, and a flat quote of $2,900, which is the middle of the band this site's model produces for that job. Working through the three units:

Flat to per square foot. $2,900 divided by 1,200 square feet is $2.42 per square foot.
Per square foot to bags. One bag of the anchor product covers 39.5 square feet at R-49, so the job is 1,200 divided by 39.5, about 30 bags, or 31 bought whole.
Per square foot to per bag installed. $2.42 times 39.5 square feet is about $96 a bag installed, of which $67.58 is the retail material.

That last line is the useful one. It splits a quote into the part you can verify at a retailer today and the part you are paying the contractor for, without needing the contractor to itemise anything. It also exposes the trap in per-bag pricing: a bag is not a fixed quantity of insulation, it is a fixed quantity of fibre spread to whatever depth the target demands.

Bags, material cost and coverage, by target R-value

Everything below is computed from one named product, Owens Corning AttiCat blown-in fibreglass, 27.5 lb bag, at $67.58 a bag. That is a retail shelf price, read on the date in the sources note. A contractor buys below it, and the size of that discount has not been measured here, so it is not applied.

Target	Sq ft per bag	Bags per 1,000 sq ft	Whole bags to buy	Retail material per 1,000 sq ft	Retail material per sq ft	Coverage basis
R-30	68.5	14.6	15	$987	$0.99	Published point
R-38	52.8	19.0	19	$1,281	$1.28	Interpolated
R-49	39.5	25.3	26	$1,711	$1.71	Published point
R-60	31.8	31.4	32	$2,125	$2.13	Published point

The published-versus-interpolated distinction matters. The manufacturer publishes coverage at R-19, R-30, R-49, R-60, and those rows are read straight off the chart. R-38 sits between two of them and is computed here rather than read, on the quantity that behaves close to linearly: the product of R times coverage, not the coverage line itself. That method is worth trusting because it was checked against a figure it did not have. Working only from the three lower published rows, the product method predicts 31.1 square feet a bag at R-60 against a published 31.8, while extrapolating the coverage line predicts 22.7. The common shortcut of halving the R-30 coverage is worse still: it predicts 34.3 square feet a bag, so an order built on it lands about 7 percent short of the bags the job needs. The blown-in method page works that arithmetic through the published rows in full, and the attic insulation calculator runs it on your own floor area.

Two consequences follow for a budget. First, the material line is not proportional to the R-value: doubling the target from R-30 to R-60 multiplies retail material per square foot by about 2.2, not by two, because loose fibre compresses under its own weight and a deeper layer is a denser one. The U.S. Department of Energy describes the same effect: settled density rises with installed thickness, so R-value does not scale strictly with depth. Second, the last step up costs more than it looks: R-49 to R-60 is a 22 percent rise in target and about a 24 percent rise in material. Both of those are material effects, so they survive whatever a contractor charges for labour, and both are worth raising when a bid offers two targets at a difference that looks proportional.

Doing it yourself: the saving, priced

One worked attic, 1,200 square feet to R-49, which is the ENERGY STAR retrofit target for a partly insulated attic in climate zones 4 through 8. The do-it-yourself column is material only, at the same retail price the model uses, bought in whole bags.

Line	Do it yourself	Hire it out
Material, 31 bags at retail	$2,095	Included
Labour, 10.8 to 14.4 crew-hours (estimate)	Your own time	Included
Blower rental, baffles, depth markers	Price locally	Included
Respirator, sealed eye protection, gloves, coveralls	Price locally	Included
Bag disposal and cleanup	Price locally	Included
Total	$2,095 plus the three priced-locally lines	$2,600 to $3,200

Subtract the column: $2,600 minus $2,095 is $505, and $3,200 minus $2,095 is $1,105. That gap, before any of the locally priced lines, is 19 to 35 percent of the installed figure, and it is the entire prize. It is smaller than the usual framing of this decision because material dominates the job and you buy material at the same shelf price the model does, while the contractor buys below it.

The three lines with no figure come out of that gap, so price them before deciding rather than after: a machine day at the rental counter, baffles by the rafter bay and depth markers, and a fitted respirator with sealed eye protection and gloves. The respirator is not optional in a hot confined attic full of airborne fibre. Worth knowing which way the rules run: OSHA's respiratory protection standard binds an employer with respect to the crew it sends, so a contractor's people work under it, while a homeowner in their own attic is outside it entirely. The airborne fibre is the same either way, and on a rented machine the protection is nobody's job but yours.

Two more things the table cannot show. 31 bags is about 853 lb of material to move, cut open and feed into a hopper, which is a second person's whole afternoon. And the crew-hour figure behind the labour line is an estimate drawn from secondary trade guidance, not a measurement, so the 10.8 to 14.4 crew-hours is a bracket for a crew that does this daily. A first attempt runs longer.

What moves the per square foot number

The model prices blowing loose fibre into an open, accessible, empty attic and nothing else. Six things move a real per-square-foot figure away from it. The hub's quote table lists which scope lines push a bid above the band; what follows is what each one does to the per-unit arithmetic, which is a different question and the one that decides whether a bid is expensive for its size.

1. The target R-value, which is not linear

Shown above: R-30 to R-60 doubles the target and multiplies retail material per square foot by about 2.2. Installed, the same move runs from $1.46 to $1.93 per square foot up to $2.60 to $3.07. When a contractor quotes two options and the deeper one costs more than proportionally more, that is the material behaving normally, not a markup.

2. Access, which is hours rather than square feet

Difficult access buys hours, and hours are a fixed block against a labour line that shrinks with floor area. At the burdened rate of $52.64 to $78.96 a crew-hour, both inputs estimates, one extra hour is about 14 percent of the low end of the modelled labour line on an 800 square foot attic and about 6 percent on a 2,000 square foot one. That is why a hard hatch, a low pitch or no walkable framing wrecks the per-square-foot figure on a small attic and barely dents it on a large one, and why two bids on differently sized attics cannot be compared per square foot at all when one of them is a crawl.

3. Baffles, which follow the perimeter and not the floor

Rigid vent chutes go into every rafter bay at the eaves before loose fibre goes near the soffits. Priced per bay, the count tracks eave length: 75 bays per 100 feet of eave at 16 inches on centre, 50 at 24 inches. Two attics of the identical 1,200 square feet do not carry the same number. A 20 by 60 foot rectangle has 120 feet of eave along its two long sides, about 60 bays at 24 inches on centre; a square one of the same area has about 69 feet and 35 bays. Same floor, near enough twice the baffle line. Measure your own eave run before treating a baffle charge as padding.

4. Air sealing, which does not scale with area at all

Sealing top plates, wiring and plumbing penetrations, dropped soffits and the hatch perimeter is slow hand work, and its hours track how many holes are in the ceiling rather than how many square feet. A per-square-foot figure therefore cannot carry it: two bids on the same attic are comparable per square foot only if both include it or both exclude it. Ask which, then compare the remainder.

5. Obstructions

Ductwork lying across the joists, a masonry chimney needing a dam, recessed fixtures without an insulation contact rating needing clearance, knee walls, and stored belongings that have to come out first. Each is hand work before the hose starts, and none of it appears in a figure derived from floor area.

6. Minimum job charges

The model is linear in floor area and the market is not. A 600 square foot attic to R-49 models at $1,300 to $1,600, of which the labour line is only $284 to $569 for 5.4 to 7.2 crew-hours, both estimated inputs. The installation cost page works the floor-price effect through in full.

Fibreglass and cellulose on price

The tempting shortcut is to reason from R per inch. Blown cellulose runs R-3.2 to R-3.8 per inch against blown fibreglass at R-2.2 to R-2.7, so cellulose reaches the same target in less depth. That does not translate into a price, because the cost of a blown job is bags, not inches. Bags come from a product's own coverage chart, which is set by its bag weight, its blown density and how much it settles. A denser material reaching a target in fewer inches can still weigh more per square foot and therefore need more material by weight. Depth and cost are different questions and the R per inch figure only answers the first.

To price a cellulose job, take two numbers off the specific product being quoted: the bag price, and the published coverage in square feet per bag at your target R-value, settled rather than installed. Those two run through the same arithmetic as the table above, floor area divided by coverage for bags and bags times price for material. Coverage charts on loose-fill packaging are required under the FTC R-value Rule (16 CFR Part 460), and cellulose products are specified under ASTM C739, so both numbers are on the bag or on the manufacturer's sheet. The dollar figures on this page are for one fibreglass product and do not price a cellulose job. The blown-in method page compares the two materials on density, dust, weight on the ceiling and how each behaves out of a rental machine.

The rent-or-hire arithmetic

Run the condition test on the method page first. It asks whether the attic is safe and suitable to work in, and if yours fails any row there, the arithmetic below does not apply at all. For an attic that passes, this is the money version.

Start with what a do-it-yourself hour is actually worth. The labour line in this model is the trade wage times the burden multiplier, which comes to $52.64 to $78.96 per crew-hour. That is the gross rate your own hours earn against a quote, and it does not change with attic size or with target R-value. What changes with attic size is how many hours you buy at that rate.

Attic floor area	Crew-hours (estimate)	Labour line, the maximum saving	Bags at R-60
800 sq ft	7.2 to 9.6	$379 to $758	26
1,000 sq ft	9.0 to 12.0	$474 to $948	32
1,200 sq ft	10.8 to 14.4	$569 to $1,137	38
1,500 sq ft	13.5 to 18.0	$711 to $1,421	48
2,000 sq ft	18.0 to 24.0	$948 to $1,895	63

Note what the third column does not do: it does not move with the target R-value. Raising the target buys more material, not more labour, in this model. A deeper blow does take somewhat longer in reality, so treat that as a limit of the model rather than a finding. The practical effect stands either way: the higher your target, the smaller the do-it-yourself saving as a share of the job.

Work down these in order and stop at the first that fits.

Under about 1,000 square feet, at any target. The most the labour line can return is $948 and the low end is $474. Against a machine rental, a respirator, baffles and two people for a day, hire it out. The saving is too thin to carry the locally priced lines.
Roughly 1,000 to 1,500 square feet, target R-30 to R-49, attic open and walkable, ceiling already air sealed. The labour line is $474 to $1,421 for 9.0 to 18.0 crew-hours. Renting is the reasonable call, with two able people and a full day booked rather than an afternoon.
Over about 1,500 square feet, or any attic at R-60. The saving keeps growing, but so does the handling: 2,000 square feet at R-60 is 63 bags to move and feed. Rent only with three people and a cleared day, otherwise hire.

One thing the burdened rate hides, and it is the reason the recommendation leans toward hiring more often than a raw dollar gap suggests. The 2.0 to 3.0 multiplier on the wage is not profit, and the installation cost page takes apart what it actually buys. Doing the job yourself does not delete those costs, it moves them to you, as rental, as equipment and as risk. That multiplier is an estimate rather than a measurement, and it is the single input on this page most worth narrowing.

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You may not need this

We do not sell insulation and we do not install it, which is why this section exists. Three cases where the bag count says buy less, or nothing.

The gap left is under a bag per 100 square feet. ENERGY STAR recommends R-60 for a bare attic in climate zones 4 through 8, with lower targets in the warmer zones. An attic already measuring about R-50 needs roughly 5.6 more bags per 1,000 square feet to close the last R-10, which is about 0.6 of a bag per 100 square feet and $377 of material spread across the whole floor. Nobody mobilises a machine, a crew and a truck for that, and heat flow falls as one over R, so the last increment returns a small fraction of the first. That R-10 threshold is an editorial judgement labelled as an estimate rather than a measurement. The depth checker turns your measured inches into an R-value range before you spend anything.
The quote prices a bare attic and yours is not bare. A coverage chart gives the bags for a full install onto a bare ceiling, so a bid built straight off the target row prices material that is partly already up there. On 1,000 square feet going from about R-30 to R-60, the difference between the two chart rows is about 16.8 bags and $1,139 of material, against 31.4 bags and $2,125 for the full-depth row. New material compresses the settled layer under it, so treat that subtraction as a floor rather than an exact figure, and ask which row the bag count on your bid came from.
The old material is coming out anyway. Where it is wet, mouldy or rodent-fouled, bags blown on top get bought twice, once now and once after the removal that was always going to happen. Remove or add over runs that test. If there is loose vermiculite on the floor, stop and treat it as potentially asbestos-containing per EPA guidance.

Recommended levels above are ENERGY STAR retrofit guidance, based on 2021 IECC Residential Provisions Table R402.1.3. Energy codes apply to new construction and permitted work, not usually to voluntarily adding insulation to an attic you already have. Which edition applies where you live depends on your state and often your city, and your local building department is the only authority on it.

Common questions

How much is blown-in insulation per square foot?: Material alone, at retail shelf price, is $0.99 per square foot at R-30, $1.71 at R-49 and $2.13 at R-60, computed from one named product's published price and coverage. Installed, the model on this site adds a labour line of $0.47 to $0.95 per square foot, giving $1.46 to $1.93 at R-30 and $2.18 to $2.66 at R-49. The labour side rests on a burden multiplier and a crew-hour figure that are estimates, not measurements.
How much does one bag of blown-in insulation cover, and what does it cost?: The measured anchor this site carries is Owens Corning AttiCat blown-in fibreglass, 27.5 lb bag at $67.58, a retail price read on the date in the sources note. Its published coverage is 110.7 square feet at R-19, 68.5 at R-30 and 39.5 at R-49. Coverage is the number that matters, not the price: one bag buys less area the deeper you go, so 1,000 square feet takes 15 whole bags at R-30 and 32 at R-60. Every product differs and its own bag label is the authority.
Why is a per-bag installed price higher at R-30 than at R-60?: Because a bag covers more floor at R-30, so more of the labour line rides on each one. In this model labour scales with floor area and not with depth, at $0.47 to $0.95 per square foot, while material is a flat $67.58 a bag. That puts the installed cost of a bag at roughly $100 to $132 at R-30 and $83 to $98 at R-60. The labour side of those rests on a burden multiplier and a crew-hour figure that are estimates, not measurements. Two per-bag quotes at different targets cannot be compared at all until both are converted to a per-square-foot figure.
What is the do-it-yourself saving on blown-in insulation, in dollars?: Smaller than the headline suggests, because material dominates the job. On a 1,200 square foot attic to R-49, 31 bags at retail is $2,095, against a modelled installed $2,600 to $3,200, whose labour side rests on a burden multiplier and a crew-hour figure that are estimates rather than measurements. The whole prize is $505 to $1,105, or 19 to 35 percent, and out of it come the blower rental, a fitted respirator, eye protection, gloves, baffles, depth markers and the trips. Price those locally before deciding. You also buy material at the same retail price a contractor buys below.
Why does doubling the R-value cost more than double in material?: Loose-fill compresses under its own weight, so a deeper layer is a denser layer and yields less R per inch than a shallow one. The manufacturer's own chart shows it: R times coverage per bag falls as the labelled R rises. Going from R-30 to R-60 doubles the target but multiplies retail material cost per square foot by about 2.2. Halving the R-30 coverage to get an R-60 figure predicts 34.3 square feet per bag where the manufacturer publishes 31.8, so an order built on the shortcut lands about 7 percent short of the bags the job needs.
Does blown cellulose cost less than blown fibreglass?: R per inch cannot answer that. Cellulose runs R-3.2 to R-3.8 per inch against fibreglass at R-2.2 to R-2.7, so it reaches a target in less depth, but the cost of a blown job is bags rather than inches, and bags come from a product's own coverage chart, bag weight and settled density. A denser material that needs fewer inches can still need more material by weight. To price a cellulose job, take the bag price and the published coverage at your target R-value from the specific product being quoted and run the same two steps as the table on this page: floor area divided by coverage gives bags, bags times bag price gives material. The figures here are for one fibreglass product and do not price cellulose.
How many bags do I need for a 1,000 square foot attic?: For the anchor product, 15 whole bags at R-30, 19 at R-38, 26 at R-49 and 32 at R-60, each rounded up from the exact coverage figure because bags are sold whole. R-30 and R-49 sit on the manufacturer's published coverage points; R-38 and R-60 are interpolated between and beyond them. Round up rather than down, because a hopper left short at the far corner of an attic costs a second trip. The bag label of the product actually blown is the authority over any table.

Sources: Material price, coverage and bag weight are the published figures for one named product, Owens Corning AttiCat blown-in fibreglass, 27.5 lb bag, at $67.58 per bag: Manufacturer coverage as published on the retail listing, 2026-08-07. The bag label is the authority for the product actually bought. Retail shelf price. A contractor buys below it, so material in an installed quote is lower than this. The discount is not measured. Coverage is published at R-19, R-30, R-49, R-60; figures shown at other targets are interpolated on the product of R times coverage rather than on coverage itself, and are marked as interpolated in the table. Bag counts, material per square foot and per-bag installed prices on this page are computed from those figures at build time. Labour is 9 to 12 crew-hours per 1,000 square feet at the BLS Occupational Employment and Wage Statistics May 2025 national mean of $26.32 per hour for SOC 47-2131, Insulation Workers, Floor, Ceiling and Wall, times a burden multiplier of 2.0 to 3.0. Both the crew-hour range and the burden multiplier are estimates rather than measurements and every total here inherits that. Settling behaviour per U.S. Department of Energy guidance that settled density rises with installed thickness. Loose-fill coverage charts and labelled R-values are governed by the FTC R-value Rule (16 CFR Part 460), using test methods such as ASTM C518; cellulose is specified under ASTM C739. R per inch ranges for blown fibreglass and blown cellulose from this site's reference data. Framing on-centre spacings behind the baffle count are the standard 16 and 24 inch figures in that same reference data. Respiratory protection: OSHA's standard binds employers with respect to their employees, so it is cited above as what covers a contractor's crew and not as a rule on a homeowner. Recommended attic levels from ENERGY STAR, "Recommended Home Insulation R-Values", based on 2021 IECC Table R402.1.3. Limits: one measured product cannot price every product, material is shown at retail and a contractor pays less, there is no measured cellulose price, machine rental, baffle or protective equipment figure here so none is published, the model carries no minimum job charge, subtracting one coverage row from another understates a top-up slightly because new material compresses the layer beneath it, and the "within about R-10" threshold is an editorial judgement labelled as an estimate. Page reviewed August 2026. Corrections: [email protected].