Calculate exactly how many bags of cellulose insulation you need, the required thickness, and estimated cellulose insulation cost. Works for Greenfiber, TAP, Johns Manville, and Applegate blown-in cellulose.
Enter your area dimensions and target R-value. Our cellulose insulation estimator handles the rest.
Cellulose insulation is a type of loose-fill insulation made from recycled paper products (mostly newspaper) treated with fire-retardant chemicals. With an R-value of R-3.2 to R-3.8 per inch, blown-in cellulose insulation is one of the most efficient and eco-friendly insulation options available. Cellulose is typically 85% recycled content, making it the greenest choice among common insulation materials.
Unlike fiberglass batts that come in pre-cut sheets, cellulose blown in insulation is installed using a blowing machine that fills every gap, crack, and cavity. This gives cellulose superior coverage around obstacles like electrical wiring, plumbing, recessed lights, and irregular framing โ which is why it is the top choice for attic insulation retrofits.
Major brands of cellulose insulation include Greenfiber (the most popular brand sold at Lowe's and Home Depot), TAP Pest Control Insulation (cellulose treated with boric acid for pest control), Johns Manville Climate Pro, and Applegate. Our cellulose insulation calculator gives accurate estimates for all major cellulose brands because they share similar R-value per inch ratings and bag coverage rates. Whether you call it blow cellulose insulation, blown cellulose, or blown-in cellulose, the calculation is the same โ what matters is the R-value per inch and bag coverage.
Learning how to calculate cellulose insulation is straightforward. Our insulation cellulose calculator automates the math, but here is the step-by-step process:
Measure the length and width of the space you want to insulate. Multiply them together to get the total square footage.
Cellulose insulation R-value is R-3.5 per inch on average. To find the required thickness, divide your target R-value by 3.5:
For example, to achieve R-49 with cellulose: 49 รท 3.5 = 14 inches. For R-60: 60 รท 3.5 = 17.1 inches. Keep in mind that blown cellulose insulation settles 15-20% over time, so many installers add 15-20% extra thickness to maintain the target R-value long-term.
Each bag of cellulose blown in insulation covers a specific area based on the thickness (R-value). Divide your square footage by the coverage per bag at your chosen R-value:
The cellulose insulation cost depends on your brand and installation method. Multiply your square footage by the cost per square foot:
| R-Value | Thickness | Coverage per Bag | Bags for 1,000 sq ft |
|---|---|---|---|
| R-11 | 3.1 inches | 40 sq ft/bag | 25 bags |
| R-13 | 3.7 inches | 34 sq ft/bag | 30 bags |
| R-19 | 5.4 inches | 23 sq ft/bag | 44 bags |
| R-30 | 8.6 inches | 17 sq ft/bag | 59 bags |
| R-38 | 10.9 inches | 14 sq ft/bag | 72 bags |
| R-49 | 14.0 inches | 11 sq ft/bag | 91 bags |
| R-60 | 17.1 inches | 9 sq ft/bag | 111 bags |
Our cellulose insulation estimator uses these coverage rates (based on Greenfiber and industry averages) to calculate exact bag counts for your project. Brand-specific coverage may vary by ยฑ5-10% โ always check the bag label for exact numbers.
A cellulose insulation calculator is useful in these common scenarios:
Understanding cellulose insulation cost helps you budget accurately. Here is a complete breakdown by project size and installation method:
| Project | Material Cost/Sq Ft | Installed Cost/Sq Ft | 1,000 Sq Ft Total |
|---|---|---|---|
| Attic (DIY) | $0.80 โ $1.20 | N/A (DIY) | $800 โ $1,200 |
| Attic (Professional) | $0.80 โ $1.20 | $1.50 โ $2.50 | $1,500 โ $2,500 |
| Wall Dense-Pack (Pro only) | $1.00 โ $1.50 | $2.00 โ $3.50 | $2,000 โ $3,500 |
| Crawl Space / Floor | $0.90 โ $1.40 | $1.70 โ $2.80 | $1,700 โ $2,800 |
A standard 19-25 lb bag of cellulose blown in insulation costs $12-$15 at Home Depot, Lowe's, or Menards. The blown cellulose insulation r value of R-3.5 per inch means you get excellent performance per dollar โ a bag that costs $13 covers 11 sq ft at R-49, which is about $1.18/sq ft. Popular brands and their typical per-bag pricing:
| Brand | Bag Weight | Price per Bag | Where to Buy |
|---|---|---|---|
| Greenfiber Sanctuary | 19 lb | $12 โ $14 | Lowe's, Home Depot |
| TAP Pest Control | 28 lb | $15 โ $18 | TAP-certified contractors |
| Johns Manville Climate Pro | 19 lb | $13 โ $15 | Home Depot, Menards |
| Applegate | 25 lb | $14 โ $16 | Online, specialty retailers |
The cellulose insulation r value is one of the highest among loose-fill insulation materials. Here is the complete breakdown of cellulose r value per inch and the thickness needed to reach common R-values:
| Cellulose R-Value per Inch | Type | Typical Use |
|---|---|---|
| R-3.2 (low end) | Settled dense-packed cellulose | Dense-packed walls (installed R) |
| R-3.5 (average) | Standard blown cellulose | Attic floors, most projects |
| R-3.8 (high end) | Freshly blown, uncompressed | Initial installation (before settling) |
| Target R-Value | Cellulose Thickness | Settled Thickness (after 20% settling) | Install Thickness (recommended) |
|---|---|---|---|
| R-11 (Interior Walls) | 3.1 inches | 2.5 inches | 3.8 inches |
| R-13 (Exterior Walls) | 3.7 inches | 3.0 inches | 4.5 inches |
| R-19 (Floors) | 5.4 inches | 4.4 inches | 6.5 inches |
| R-30 (Warm Attic) | 8.6 inches | 6.9 inches | 10.3 inches |
| R-38 (Moderate Attic) | 10.9 inches | 8.7 inches | 13.0 inches |
| R-49 (Cold Attic) | 14.0 inches | 11.2 inches | 16.8 inches |
| R-60 (Very Cold Attic) | 17.1 inches | 13.7 inches | 20.5 inches |
Because blown-in cellulose insulation settles 15-20% over the first few years, professional installers typically add extra thickness upfront. For example, to maintain R-49 long-term, install 16.8 inches of cellulose rather than 14 inches. Our cellulose insulation calculator shows the initial install thickness so your attic hits the target R-value and stays there. Understanding the r value of cellulose insulation (and the insulation cellulose r value per inch) is essential for any cellulose project โ this single number determines how much material you need and how much it will cost.
The two most popular blown-in insulation materials are cellulose and fiberglass. Here is a side-by-side comparison to help you choose:
| Feature | Cellulose | Blown-In Fiberglass |
|---|---|---|
| R-Value per Inch | R-3.5 (higher) | R-2.5 |
| Material | 85% recycled paper + fire retardant | Glass fibers (20-30% recycled) |
| Cost per Sq Ft | $0.80 โ $1.50 | $0.70 โ $1.30 |
| Eco-Friendliness | Excellent (highest recycled content) | Moderate |
| Air Sealing | Excellent (dense, fills gaps) | Good |
| Moisture Resistance | Can absorb moisture | Does not absorb |
| Settling | 15-20% over time | Minimal (5% or less) |
| Fire Resistance | Class 1 (treated with boric acid) | Naturally non-combustible |
| Soundproofing | Excellent (denser material) | Good |
| Best For | Attics, existing walls, soundproofing | Humid climates, walls in new construction |
For most attic insulation projects, cellulose insulation is the better choice because of its higher R-value per inch, superior gap coverage, and eco-friendly credentials. If you live in a very humid climate or your attic has any moisture issues, fiberglass may be the safer option. For a complete breakdown of blown-in options, see our blown in insulation calculator.
Installing cellulose insulation yourself is one of the most accessible DIY projects. A typical 1,000 sq ft attic takes 2-4 hours with a helper and saves 40-60% compared to professional installation.
Need a different insulation calculation? Try our other free tools: