Attic Insulation Calculator

What Is an Attic Insulation Calculator?

An attic insulation calculator is a tool designed to help you determine exactly how much insulation you need to add to your attic to meet modern energy efficiency standards. Proper attic insulation is one of the most cost-effective ways to lower your heating and cooling bills. This free tool calculates the required depth and estimates the number of bags of loose-fill insulation for your project, saving you time and money.

Last updated: November 8, 2025

How to Use This Calculator

Our insulation calculator provides an accurate material list in a few simple steps:

1. Enter Attic Area: Input your attic's square footage (length x width).
2. Select Your Climate Zone: Choose your U.S. Climate Zone to determine the target R-value for your home.
3. Measure Existing Insulation: Use a ruler to measure the current depth of your insulation in inches.
4. Choose New Insulation Type: Select the type of loose-fill insulation you plan to add.
5. Click "Calculate": Get an instant estimate of the additional depth needed and the number of bags to buy.

Understanding Your Attic Insulation Results

Our calculator gives you actionable numbers to guide your project and purchasing.

• Target R-Value: This is the recommended insulation level for your specific climate zone, according to the Department of Energy. A higher number means more insulation.
• Additional Depth Needed: This is the number of inches of new insulation you need to add on top of your existing layer to reach the target R-value.
• Estimated Bags Needed: This gives you a practical shopping list, estimating the number of bags of your chosen insulation type required for the job.

Properly insulating your attic can save you 10-20% on your annual heating and cooling costs, according to ENERGY STAR.

Example Attic Insulation Calculation

Here's a common scenario for a home in a moderate climate.

Frequently Asked Questions