calcs.homes
calcs.homes
Enter your attic area and current and target R-value to get blow-in insulation depth, bags needed, and cost. Uses the US/Imperial R-value scale common on North American insulation bags.
Estimate only — bag coverage varies by brand; check the coverage chart printed on your bag.
We subtract your current R-value from the target to find how much additional R-value you need, then divide by the material's R-value per inch to get depth. Multiplying area by that depth gives total volume, which we divide by a typical bag yield to get bag count. Always check the coverage chart on your specific bag — settled density varies by brand and batch.
Most US climate zones recommend R-38 to R-60 for attics — check your local energy code or the Department of Energy's zone map for a specific target.
It depends on your attic's area, the R-value gap you're filling, and the material's coverage per bag — this calculator combines all three. Always cross-check against the coverage chart on your specific bag.