Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Total insulation cost
$2,700
Blown-in insulation material + labor
$2,400
Old insulation removal
$0
All-in cost per sq ft
$2.25
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter attic floor area (sq ft).
- 2Enter target r-value & material.
- 3Enter eave baffle installation ($).
- 4Enter remove old insulation first?.
- 5Enter removal rate ($/sq ft).
- 6Read your total insulation cost on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
Blown-in attic insulation cost is driven by attic square footage, target R-value (which determines how many inches deep the material needs to be blown), and material choice between cellulose and fiberglass, which price differently per bag and per square foot at a given depth. This calculator prices the job using a per-square-foot rate that already reflects the depth needed to hit your target R-value, then adds an allowance for baffle installation (needed at eave vents to maintain airflow) and existing insulation removal if the attic has old, contaminated, or wet insulation that needs to come out first. 2026 US national averages run about $1.50-$2.50 per square foot for a standard fiberglass blow-in to R-38 (roughly 12-14 inches), and $1.75-$3.00 per square foot for cellulose, which is denser and offers slightly better sound dampening and fire resistance. Removing old insulation first typically adds $1-$2 per square foot. Most of the US falls into recommended attic insulation levels of R-38 to R-60 depending on climate zone — colder northern climates should target the higher end of that range.
Worked example
Using the values the calculator loads with:
Inputs
- Attic floor area: 1200 sq ft
- Target R-value & material: Cellulose to R-38 — $2.00/sq ft
- Eave baffle installation: 300 $
- Remove old insulation first?: No — blowing over existing
- Removal rate: 1.5 $/sq ft
Results
- Total insulation cost: $2,700
- Blown-in insulation material + labor: $2,400
- Old insulation removal: $0
- All-in cost per sq ft: $2.25
What each field means
Inputs
- Attic floor area (sq ft)
- The attic floor area used in the calculation, measured in sq ft. Starts at 1200 sq ft so you have a working example on load. Accepted range: 200–6000 sq ft.
- Target R-value & material
- Pick the option that matches your situation — the maths changes per option. Choices: Fiberglass to R-38 — $1.60/sq ft, Fiberglass to R-60 — $2.20/sq ft, Cellulose to R-38 — $2.00/sq ft, Cellulose to R-60 — $2.60/sq ft.
- Eave baffle installation ($)
- The eave baffle installation used in the calculation, measured in $. Starts at 300 $ so you have a working example on load. Accepted range: 0–1200 $.
- Remove old insulation first?
- Pick the option that matches your situation — the maths changes per option. Choices: No — blowing over existing, Yes — remove old first.
- Removal rate ($/sq ft)
- The removal rate used in the calculation, measured in $/sq ft. Starts at 1.5 $/sq ft so you have a working example on load. Accepted range: 0.5–3 $/sq ft.
Results
- Total insulation cost
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Blown-in insulation material + labor
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Old insulation removal
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- All-in cost per sq ft
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Cellulose or fiberglass — which is better for attics?
Both perform similarly for thermal resistance at the same R-value; cellulose is denser and settles slightly less over time with better sound dampening and fire-retardant treatment, while fiberglass is lighter, doesn't absorb moisture as readily, and is usually a bit cheaper per square foot.
Do I need to remove old insulation before blowing in new insulation?
Not usually — new insulation can typically be blown directly over old fiberglass batts or loose-fill as long as it's dry and not contaminated with mold, pest droppings, or vermiculite (which may contain asbestos and requires special abatement removal instead).
What are baffles and why do they matter?
Baffles are rigid channels installed at the eaves before blowing insulation that keep loose-fill material from blocking soffit vents, preserving the airflow path that ventilates the attic and prevents moisture buildup and ice dams — skipping them is a common and costly mistake.
How much can attic insulation save on energy bills?
The US Department of Energy estimates homeowners can save 10-15% on heating and cooling costs by properly insulating an under-insulated attic, with payback periods commonly in the 2-5 year range depending on local energy costs and climate.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Attic Blown-In Insulation Cost Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/attic-blown-in-insulation-cost
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/attic-blown-in-insulation-cost" target="_blank" rel="noopener">Attic Blown-In Insulation Cost Calculator — RevenueLab</a> (2026).</p>
Source: [Attic Blown-In Insulation Cost Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/attic-blown-in-insulation-cost) (2026).