Insulation Calculator

Determine batts or bags of blown insulation needed to hit your target R-value for walls, attics, and floors. Based on DOE climate zone recommendations.

Insulation estimates depend on the area to be insulated, the target R-value, and the insulation type. Batt insulation is sold in rolls and bags covering a specified square footage at a given R-value. Blown-in insulation is sold by the bag, with each bag covering a certain area at a certain settled depth. This calculator handles both types and accounts for framing factor (the percentage of wall area occupied by studs rather than insulation cavities).

Frequently Asked Questions

What R-value do I need for my climate zone?

IECC 2021 specifies minimum R-values by climate zone. Zone 3 requires R-20 walls and R-38 attics. Zone 5 requires R-20 walls and R-49 attics. Check your local jurisdiction for the exact requirement.

Is blown-in insulation better than batts?

Blown-in insulation fills irregular cavities and gaps better than batts, reducing air infiltration. Batts are faster to install in standard-framed walls. Both achieve the same R-value per inch when installed correctly.

Can I compress insulation to fit a thinner cavity?

Never compress batts to fit. Compression reduces the effective R-value significantly. Use the correct batt thickness for your cavity depth, or switch to a higher-R-per-inch material.

Estimates are for planning purposes only. Verify quantities with your supplier and confirm code requirements with your local building department.