Blown-in insulation costs about $0.60 to $2.30 per square foot installed for cellulose — with typical attic jobs landing between roughly $1,000 and $3,900 depending on size and target depth — while the material alone runs $0.30 to $0.75 per square foot if you blow it yourself. Most attics in cold climates want R-49 to R-60, which is 13 to 18 inches of cellulose. Here's what drives the number, zone by zone and bag by bag.
Installed pricing for loose-fill cellulose spans a wide band because the quote bundles three things: material, machine time, and the labor of two people working an awkward space. Current 2026 figures from the major cost trackers:
| Source | Cellulose, installed | What it reflects |
|---|---|---|
| HomeGuide (2026) | $0.60-$4.20/sq ft | Full market range across project sizes and regions |
| Homewyse (May 2026) | $1.67-$2.92/sq ft | Mid-band with typical labor rates |
| Bob Vila | $1.00-$1.50/sq ft | Typical straightforward attic job |
| Material only (DIY) | $0.30-$0.75/sq ft | Bags at big-box pricing, no labor |
Loose-fill fiberglass quotes a bit lower per bag, but it insulates less per inch — R-2.9 to R-3.1 against cellulose's R-3.7 — so hitting the same target takes more inches and more bags. At equal R-value the installed prices converge. Mineral wool blows too, but it's the premium loose-fill and usually only worth it where fire resistance matters most.
Applying those bands to common attic footprints, with bag counts for a full R-49 build-out where coverage runs 40-67 square feet per bag:
| Attic size | Bags at R-49 | DIY materials | Installed (pro) |
|---|---|---|---|
| 800 sq ft | 11-20 | $240-$600 | $800-$1,840 |
| 1,200 sq ft | 17-30 | $360-$900 | $1,200-$2,760 |
| 1,700 sq ft | 25-42 | $510-$1,275 | $1,700-$3,910 |
| 2,400 sq ft | 35-60 | $720-$1,800 | $2,400-$5,520 |
Top-ups cost less than the table suggests: if you already have six inches of cellulose down, you're buying the difference to R-49, not the whole depth. The blow-in insulation calculator subtracts the existing layer and sizes the top-up automatically.
The target is an R-value, and the R-value depends on climate zone. The Department of Energy's attic guidance for loose-fill, in broad strokes:
| Climate zone | Attic R-value target | Cellulose depth needed |
|---|---|---|
| Zones 1-2 (deep South, Gulf) | R-30 to R-49 | 8-13 in |
| Zone 3 (South Atlantic, desert SW) | R-30 to R-60 | 8-16 in |
| Zone 4 (Mid-Atlantic, Midwest edges) | R-38 to R-60 | 10-16 in |
| Zones 5-8 (North, mountain, Great Lakes) | R-49 to R-60 | 13-18 in |
Diminishing returns are real: going from an uninsulated attic to R-30 captures most of the benefit, and every R beyond that saves a little less. R-49 is the common deep-retrofit target that balances cost against performance; R-60 pays off mainly in the coldest zones or with cheap material. Cellulose settles about 20% after blowing, and manufacturer coverage charts already account for it — blow to the chart's settled depth, not the initial fluff.
Often, yes. The savings in the table above run $800 to $3,000, and the equipment barrier is low: most big-box stores loan the blower machine free or cheap with a minimum bag purchase — typically 10 to 20 bags, which most attics need anyway. The job takes two people (one feeding the hopper, one on the hose), a full day for a typical attic, and basic protection: dust mask, eye protection, walking boards across the joists.
What DIY doesn't get you: air sealing. Pros foam and caulk top plates, wire penetrations, and the chimney chase before blowing, and that step matters more than the last few inches of depth — insulation doesn't stop air movement. A fair middle path is hiring the seal-and-insulate job as a package if your attic has visible gaps, and self-blowing only when you're topping up an already-sealed space.
Per bag, fiberglass is usually cheaper. Per achieved R-value, they land close enough that the decision rides on other factors. Cellulose is denser, so it resists air infiltration and settles into odd cavities better; fiberglass is lighter, less dusty, and doesn't absorb water the way damp cellulose can if a roof leaks. Both hold their R-value for decades when installed to the labeled depth. Buy on the coverage chart, not the bag price — a $12 bag covering 40 square feet at R-49 beats a $10 bag covering 30.
In an under-insulated house, the payback is fast enough to notice. ENERGY STAR estimates that air sealing plus attic insulation trims heating and cooling costs by roughly 15%. On a house spending $250 a month on utilities, that's about $450 a year — a $1,500 to $2,500 attic job recovers its cost in three to five heating-season years, keeps saving after that, and makes the upstairs noticeably more comfortable in July while it's at it. Houses that already have R-30+ see much smaller marginal savings, which is why the first move is measuring what's up there: 13 inches of settled cellulose means your money belongs somewhere else, like the R-value calculator or the next uninsulated surface.
Bags, depth, and material cost from your square footage, target R, and existing layer.
Blow-In Insulation Calculator →Budget $1.00 to $2.30 per square foot installed for cellulose — roughly $1,200 to $2,760 on a 1,200-square-foot attic — or $0.30 to $0.75 per square foot doing it yourself with a loaner machine. Seal the air leaks first, target R-49 in the northern two-thirds of the country, and verify depth with rulers stapled to the joists. The blow-in calculator sizes the bags, the insulation calculator checks R-values surface by surface, and if the attic project is part of a bigger finish — new ceiling board below, walls opened up — the drywall calculator prices the board that closes it back up.
Professionally blown cellulose runs about $1,200 to $2,760 for 1,200 square feet at the $1.00-$2.30 per square foot band; many straightforward attic jobs land near $1,200-$1,800. Doing it yourself with rented or loaner equipment cuts that to roughly $360-$900 in materials.
Loose-fill fiberglass usually costs a bit less per bag than cellulose, but cellulose insulates better per inch (about R-3.7 versus R-2.9-3.1), so you need fewer inches to hit the same target. At equal R-value the installed prices are close, and cellulose's denser fill resists air movement better.
Coverage runs roughly 40-67 square feet per bag at R-49 depending on product, so a 1,200 sq ft attic takes about 17-30 bags. The coverage chart printed on each bag is the legally binding number — use it for the final count.
Usually yes in an under-insulated attic. Air sealing plus attic insulation can cut heating and cooling costs by roughly 15% per ENERGY STAR estimates, so a $1,500-$2,500 job on a house with $250 monthly utility bills can recover its cost in a few heating seasons, then keep paying.
Yes, if the existing layer is dry and unfaced — no vapor barrier buried in the middle. Subtract the existing layer's R-value from your target and blow only the difference on top, which the blow-in calculator sizes automatically.