Insulation Calculator
Estimate insulation materials needed for attics, walls, and floors. Calculate bags or batts required with R-value calculations for fiberglass, cellulose, spray foam, and mineral wool insulation.
Complete Guide: Insulation Calculator
Everything you need to know about using this tool effectively
This insulation calculator helps you figure out how much material you need based on the area to insulate, your target R-value, and the type of insulation you plan to use. Enter your square footage and desired thermal resistance to get an accurate estimate of bags, rolls, or board feet required.
An online tool that calculates insulation material requirements for residential and commercial projects. It accounts for different insulation types including fiberglass batts, blown-in cellulose, spray foam, and rigid board. The calculator factors in R-value per inch for each material to give you a realistic estimate of total thickness and quantity needed.
Attic Insulation Projects
Plan how many bags of blown-in insulation or rolls of batts you need to bring your attic up to the recommended R-value for your climate zone.
Wall Retrofit Estimates
Calculate material requirements for adding insulation to existing walls during a renovation or energy upgrade.
New Construction Planning
Determine total insulation budget and material orders for a new build based on architectural plans and local energy codes.
Energy Efficiency Upgrades
Compare insulation types and thicknesses to find the most cost-effective way to improve your home's thermal performance.
Enter the Area
Type the total square footage or square meters of the surface you want to insulate.
Set Your Target R-Value
Input the R-value recommended for your region and application, such as R-38 for attics in cold climates.
Choose a Material Type
Select from fiberglass batts, blown-in cellulose, spray foam, or rigid board insulation.
Review Your Results
The calculator shows required thickness, total material quantity, and number of bags or rolls to purchase.
Check your local building code for minimum R-value requirements before purchasing materials.
Buy 10 percent extra material to account for cutting waste and gaps around obstructions.
Blown-in insulation settles over time, so factor in compaction when estimating coverage.
Seal air leaks with caulk or spray foam before adding insulation to maximize effectiveness.
Layer different insulation types for better coverage in hard-to-reach areas like rim joists.
What R-value do I need for my attic?
Most US homes need between R-30 and R-60 in the attic depending on climate zone. Colder regions like the northern US typically require R-49 or higher, while warmer southern regions may only need R-30.
What is the difference between R-value and U-value?
R-value measures resistance to heat flow, so higher numbers mean better insulation. U-value measures heat transfer rate, so lower numbers indicate better performance. R-value is the inverse of U-value.
How many bags of blown-in insulation do I need?
The number of bags depends on the target depth and the coverage per bag listed on the product packaging. This calculator divides your total volume requirement by the per-bag coverage to give you an accurate count.
Can I use this calculator for commercial projects?
Yes, the calculator works for both residential and commercial applications. Just enter the total area and target R-value for your specific building envelope requirements.
Does insulation type affect the R-value calculation?
Yes, different materials have different R-values per inch. For example, fiberglass batts provide about R-3.1 per inch while closed-cell spray foam provides roughly R-6.5 per inch, so the required thickness varies by material.