Attic Insulation Cost Calculator
Get an instant free estimate for attic insulation — blown-in, batts, and spray foam.
Free Attic Insulation Cost Calculator
Use this calculator to calculate the cost of attic insulation near you for free. Enter your ZIP code for a localized estimate.
Attic Size
Enter the attic floor area in square feet — usually close to the footprint of the floor below it.
Insulation Type:
Target R-Value:
Existing Insulation:
Additional Services:
Estimates are instant and require no contact information.
Based on inputs, your Attic Insulation project cost is approximately:
Note that the cost above is purely an estimate.
The actual cost may be higher or lower depending on the contractor's quote.
How Much Does Attic Insulation Cost?
Attic insulation typically costs $1,500 to $4,000 — about $1.40 to $2.00 per square foot for blown-in fiberglass and cellulose (the popular attic choices) and $3.50 to $7.00 for spray foam. For an average 1,000–1,200 sq ft attic at R-38 to R-49, expect roughly $1,800 to $3,500 with blown-in.
The cost scales with the attic size, the insulation type, the target R-value(driven by your climate), and whether old insulation must be removed first. Two things punch above their weight: air sealing (often the most cost-effective step, and frequently required for rebates) and the federal 25C tax credit (30% of materials, up to $1,200/year). Use the calculator above to localize the estimate, then read on for how to choose your material and R-value and capture the incentives.
Attic Insulation Cost by Type & R-Value
Average Cost by Insulation Type (1,000 sq ft Attic)
| Insulation Type | Per Sq Ft | ~1,000 Sq Ft | Best For |
|---|---|---|---|
| Fiberglass Batts | $1.00 – $1.80 | $1,000 – $1,800 | Accessible joists, DIY |
| Blown-In Fiberglass | $1.20 – $2.00 | $1,200 – $2,000 | Fast coverage, most popular |
| Blown-In Cellulose | $1.40 – $2.20 | $1,400 – $2,200 | Dense, eco-friendly |
| Open-Cell Spray Foam | $3.00 – $4.50 | $3,000 – $4,500 | Air seal + insulate |
| Closed-Cell Spray Foam | $5.00 – $7.00 | $5,000 – $7,000 | Max R/inch, moisture barrier |
Source: Baseline labor anchored to U.S. Bureau of Labor Statistics, Insulation Workers (SOC 47-2131); material and ranges reflect our aggregated contractor quote data across U.S. markets. Assumes a common R-38.
R-Value Target by Climate (DOE Guidance)
| Climate | Recommended R-Value | Cost vs. R-38 |
|---|---|---|
| Warm / Southern | R-30 – R-38 | −15% to baseline |
| Mixed / Moderate | R-38 – R-49 | Baseline to +20% |
| Cold / Northern | R-49 – R-60 | +20% to +40% |
Source: U.S. Department of Energy recommended attic R-values by climate zone. Add-ons (air sealing, removal, vapor barrier, baffles, hatch, ventilation) are extra. Regional adjustments applied via the calculator above.
The 6 Factors That Drive Your Quote
1. Attic Size
Insulation is priced per square foot of attic floor — roughly the footprint of the living space below (just the top floor's footprint on a multi-story home). Most attics run 800–1,500 sq ft. A bigger attic costs more, and a job minimum applies, so small attics cost a bit more per foot. Measure length × width or use the top-floor square footage.
2. Insulation Type
The material sets the base rate. Fiberglass batts (~$1.40/sq ft) are economical and DIY-friendly for accessible joists. Blown-in fiberglass (~$1.50) is fast and the most popular for floors. Blown-in cellulose (~$1.65) is dense and eco-friendly. Open-cell (~$3.50) and closed-cell (~$5.50) spray foam cost more but air-seal and deliver the highest R per inch.
3. Target R-Value (Climate)
R-value measures thermal resistance, and colder climates need more. The DOE recommends about R-30–R-49 in mild/southern zones and R-49–R-60 in cold/northern zones; R-38 is a common baseline. Higher R-value uses more material and scales the cost (R-60 adds about 40% over R-38). Match it to your climate zone and local energy code.
4. Existing Insulation
Insulating a bare attic, or adding new over clean, dry existing insulation ('topping up'), is the lowest cost — no extra charge. But if the old insulation is moldy, pest-damaged, water-stained, or deteriorated, it must be torn out and disposed of first, adding about $1.25/sq ft. Vermiculite needs special testing/handling. Condition decides whether you add over or remove and replace.
5. Air Sealing & Ventilation
Often the most cost-effective step: sealing gaps around can lights, penetrations, the attic hatch, and top plates before insulating stops the air leakage that insulation alone can't, maximizing savings (and it's often required for rebates). Soffit baffles keep the soffit-to-ridge airflow open above the insulation, and a ventilation fan can help — both round out a properly breathing attic.
6. Moisture, Hatch & Extras
Finishing details that protect the work: a vapor barrier/retarder manages moisture where needed, mold treatment addresses existing growth before insulating, and insulating/weatherstripping the attic hatch closes a common leak point. These per-square-foot or flat add-ons depend on your attic's condition and climate.
Which Insulation Type — and What R-Value?
Two choices shape most of the cost and performance: the material and the R-value. Here's the honest breakdown.
Pick the material by job
- Blown-in fiberglass or cellulose — best value for a vented attic floor; fills gaps and hits high R affordably.
- Fiberglass batts — economical and DIY-friendly for accessible, evenly-spaced joists.
- Spray foam (open/closed) — for air-sealing the roofline, conditioned attics, or moisture control; highest R/inch, highest cost.
Set the R-value by climate
- Warm / southern: R-30 to R-38 is usually enough.
- Mixed / moderate: R-38 to R-49 is the sweet spot.
- Cold / northern: R-49 to R-60 for the most savings (and to meet code/rebate minimums).
Don't skip these
- Air seal first — it's often the highest-ROI step and unlocks rebates.
- Keep ventilation open — baffles preserve soffit-to-ridge airflow so the attic breathes.
How to Vet a Contractor & Maximize Rebates
A good insulation job is as much about air sealing and ventilation as R-value — and doing it right unlocks tax credits and rebates. Before you hire:
- Verify licensing and insurance, and look for BPI-certified or weatherization-experienced installers.
- Confirm they air seal before insulating and keep soffit ventilation open with baffles.
- Get the target R-value in writing (and the installed depth/coverage to verify it).
- Ask about the 25C tax credit and utility rebates — and the certification statement you'll need to claim them.
What a complete quote should spell out
- The insulation type, target R-value, and attic square footage being priced.
- Whether old-insulation removal is included and how contaminated material is handled.
- Whether air sealing, baffles, vapor barrier, and the attic hatch are included or separate.
- The rebate/tax-credit paperwork, and any workmanship warranty.
Methodology & Sources
This calculator sets a per-square-foot rate by insulation type (batts, blown-in fiberglass/cellulose, or open/ closed-cell spray foam), multiplies it by an R-value factor (R-19 0.70× up to R-60 1.40×, with R-38 as baseline), and multiplies by your attic area. It adds per-square-foot old-insulation removal when needed, plus per-square-foot or flat add-ons(air sealing, vapor barrier, soffit baffles, attic-hatch insulation, mold treatment, and a ventilation fan), enforces a job minimum, and scales the result to your ZIP code's regional price level. In short: Sq Ft × (Type Rate × R-Value) + Removal + Add-ons, × Regional Factor. Baseline labor is anchored to federal insulation-worker wage data and calibrated against our aggregated contractor quotes.
Data sources:
- U.S. Bureau of Labor Statistics — Insulation Workers (SOC 47-2131)
- ENERGY STAR — Recommended Insulation R-Values
- IRS — Energy Efficient Home Improvement Credit (25C)
For a full explanation of how every calculator on this site is built and localized, see our methodology page.
About the Reviewer
Licensed Mechanical (HVAC) Contractor
Mechanical contractor specializing in residential HVAC system sizing, replacement, and indoor air quality.
View full profile & credentials →Frequently Asked Questions
Most attic insulation jobs run $1,500–$4,000, or roughly $1.40–$2.00 per square foot for blown-in fiberglass and cellulose (the popular attic choices) and $3.50–$7.00 for spray foam. For an average 1,000–1,200 sq ft attic at a typical R-38 to R-49, expect about $1,800–$3,500 with blown-in. The price scales with the attic floor area, the insulation type, the target R-value (more material for higher R), and whether old insulation has to be removed first. Enter your attic size, type, R-value, and existing-insulation situation in the calculator to anchor the estimate.
It depends on your climate. The U.S. Department of Energy recommends roughly R-30 to R-49 for warm/mild southern zones and R-49 to R-60 for cold northern zones; most attics land at R-38 to R-49. Higher R-value means better thermal resistance and lower heating/cooling bills, but with diminishing returns — going from nothing to R-38 saves far more than going R-49 to R-60. The calculator scales cost by R-value (R-38 is the baseline; R-60 adds about 40%). Check the DOE zone map or your local energy code for your target, and note that many rebates require hitting a minimum R-value.
For a standard vented attic floor, blown-in fiberglass or cellulose is usually the best value — fast to install, fills irregular gaps and around obstructions, and reaches high R-values affordably. Fiberglass batts suit accessible, evenly-spaced joists and are the most DIY-friendly. Spray foam (open or closed cell) is the premium option: it air-seals as it insulates and has the highest R-value per inch, making it ideal for converting an attic to conditioned space or sealing a complex roofline — but it costs 2–4× as much. Match the material to the job: blown-in for a vented floor, spray foam for sealing the roofline. The calculator prices all five.
It depends on the condition. If the existing insulation is dry, clean, and free of mold and pests, you can usually add new insulation right over it ('topping up') — cheaper and faster, and the calculator's 'Add Over Existing' option charges nothing extra. Remove and replace if it's water-damaged or moldy, infested with rodents (droppings/contamination), badly compressed or deteriorated, or contains older materials of concern like vermiculite (which may contain asbestos and needs testing/handling). Removal adds about $1.25/sq ft for labor and disposal in the calculator, but starting fresh ensures a healthy, fully effective result.
Almost always — air sealing is often the single most cost-effective part of the project. Insulation slows heat transfer, but it doesn't stop air leakage: gaps around recessed lights, plumbing and wiring penetrations, the attic hatch, and top plates let conditioned air escape and outside air in, undercutting the insulation. Sealing those gaps with caulk and foam before adding insulation maximizes savings and helps prevent moisture problems. Many energy pros consider it essential to get the full benefit of new insulation, and it's frequently required to qualify for rebates. The calculator includes an air-sealing add-on for exactly this.
Yes. The federal Energy Efficient Home Improvement Credit (25C) offers a tax credit of 30% of the cost of qualifying insulation and air-sealing materials, up to $1,200 per year. Many state energy offices and local utilities also offer insulation rebates — sometimes substantial — since insulation cuts grid demand. To qualify, the insulation usually must meet a minimum R-value/efficiency, and air sealing is often included or required. Keep your receipts and the manufacturer's certification statement, check the ENERGY STAR rebate finder and your utility's site, and consult a tax professional. These incentives can offset a meaningful share of the project cost.
Some types, yes — others, no. Fiberglass batts are the most DIY-accessible: cut and lay them between the joists, wearing gloves, a mask, and long sleeves (fiberglass irritates skin and lungs). Blown-in can be DIY with a rented blower (often free with material purchase), but it's a two-person job and getting even coverage in a hot, cramped attic is tough. Spray foam should always be left to professionals — it needs special equipment, precise mixing, and proper ventilation, and mistakes are costly and hazardous. Also note: DIY work may not qualify for rebates that require professional installation, and proper air sealing and ventilation detailing benefit from a pro's experience.
It lasts a long time: blown-in fiberglass and cellulose last 20–30+ years (cellulose may settle ~20%, slightly reducing R-value), batts 20–30 years, and spray foam can last the life of the home. On savings, the EPA estimates homeowners save about 15% on heating and cooling costs (around 11% of total energy) by air sealing and adding insulation in the attic and other areas — often more for severely under-insulated homes. The payback is typically just a few years, making attic insulation one of the highest-ROI energy upgrades, on top of better comfort and fewer drafts.
For most vented attic floors, blown-in (fiberglass or cellulose) wins on value: it's a fraction of the cost, reaches R-49 to R-60 affordably, and is the standard for laying insulation on the attic floor. Spray foam makes sense when you want to air-seal and insulate the roofline itself — turning the attic into conditioned space, sealing a complex or cathedral roof, or handling moisture (closed-cell adds a vapor/moisture barrier). Spray foam's higher R-per-inch matters where space is tight, but on an open attic floor you can simply add more blown-in depth for less money. So: blown-in for the floor, spray foam for the roofline or conditioned attics. The calculator prices both paths.
For a standard vented attic, yes — and it's easy to overlook. Insulation on the attic floor should not block the soffit vents, or you trap heat and moisture that shorten the roof's life and reduce efficiency. Soffit baffles (also called rafter vents or chutes) keep an air channel open from the soffit up to the ridge so the attic breathes. Proper balanced ventilation (soffit-to-ridge) prevents ice dams in cold climates and heat buildup in hot ones. The calculator includes baffles and an attic ventilation fan as add-ons. Spray-foamed (conditioned) attics are a different system that's deliberately unvented — your contractor should design ventilation to match the approach.