Insulation Calculator
Home & HVACCalculate how many batts, rolls, or bags of insulation you need for walls, attics, and basements. Supports fiberglass, cellulose, spray foam, and mineral wool.
Understanding Insulation R-Values
R-value measures insulation's resistance to heat flow. Higher R-values provide better insulation but cost more. Your location's climate zone determines the recommended R-value for walls, attics, and basements.
| Location | Mild Climate (R-) | Cold Climate (R-) | Very Cold (R-) |
|---|---|---|---|
| Wall Cavities | 13 | 15–19 | 21 |
| Attics | 30–38 | 38–49 | 49–60 |
| Basements | 13 | 15–19 | 21 |
| Crawl Spaces | 19 | 19–30 | 30 |
Insulation Types Comparison
| Type | R-Value/inch | Cost/Sq Ft | Installation |
|---|---|---|---|
| Fiberglass Batts | 3.2–3.8 | $0.30–$0.60 | DIY |
| Cellulose (Blown) | 3.6–3.8 | $0.40–$0.70 | Professional |
| Spray Foam | 6–7 | $1.50–$2.50 | Professional |
| Mineral Wool | 3.8–4.0 | $0.50–$0.80 | DIY |
How to Use This Calculator
- Enter the square footage of the area you're insulating
- Select the required R-value based on your climate zone and location (wall, attic, basement)
- Choose your insulation type (fiberglass, cellulose, spray foam, or mineral wool)
- Enter the average cost per square foot for your material
- The calculator will show units needed and total estimated cost
Frequently Asked Questions
What R-value do I need for my walls?
Wall insulation typically requires R-13 to R-15 depending on your climate zone. Consult your local building codes for specific requirements. The U.S. Department of Energy provides climate zone recommendations based on your location.
What R-value do I need for my attic?
Attic insulation needs vary by climate: R-30 to R-38 for moderate climates, R-38 to R-49 for cold climates, and R-49 to R-60 for very cold climates. Check your region's building code for exact requirements.
What is the difference between fiberglass, cellulose, and spray foam insulation?
Fiberglass batts are affordable and DIY-friendly with R-3.2 per inch. Cellulose (blown-in) offers R-3.6 per inch and fills gaps better but requires equipment. Spray foam provides R-6 to R-7 per inch, best air sealing, but is more expensive and requires professional installation.
How do I calculate how much insulation I need?
Measure the square footage of the area to be insulated and determine the required R-value for your climate zone. Divide the area by the coverage rate per unit (batt, roll, or bag) to find the number of units needed. This calculator automates that process.
Can I install insulation myself?
Fiberglass batts and rolls can be installed as a DIY project. Cellulose loose-fill and spray foam typically require professional equipment and installation. Always wear protective gear, follow manufacturer instructions, and ensure proper ventilation.
What is the cost of insulation?
Fiberglass batts cost $0.30–$0.60 per sq ft. Cellulose costs $0.40–$0.70 per sq ft. Spray foam is most expensive at $1.50–$2.50 per sq ft. Prices vary by region and material quality. Our calculator helps you estimate total project costs based on current pricing.