What is an Attic Insulation Calculator?

Your attic is an essential space—it’s the place to store everything from holiday decorations to camping equipment and the first line of defense against a high energy bill.

That said, your attic can wreak havoc on your wallet if it’s not properly insulated. This is because your attic’s insulation helps regulate your home’s heat flow. In short, an under-insulated attic can greatly drive up energy costs.

But how do you know how much insulation you need to properly insulate your attic?

The answer: an attic insulation calculator.

Knowing what an attic insulation calculator is and how it works will greatly benefit you when it comes to insulating your attic.

Calculating Insulation Requirements

Although it sounds like an intricate machine, an attic insulation calculator is simply a mathematical formula that lets you know roughly how much insulation you’ll to properly insulate your home.

In its most basic sense, insulation consists of any material placed in a home’s gaps or crevices in order to regulate heat flow. Without proper insulation, heat escapes from your home in the cold winter months and enters your home during summer.

To calculate insulation requirements, follow the steps below.

#1 Measure Your Attic

If your attic is square or rectangular, measuring your attic should be a piece of cake. Simply measure your attic’s length and width and multiply those two figures together to yield your attic’s square footage.

If your attic consists of triangular spaces, you’ll need to measure the height and width of each triangle. Then, divide the base in half and multiply it by the triangle’s height to yield the area’s square footage. 

#2 Measure Current Insulation Levels 

If your attic’s uninsulated, you have no old insulation to measure. But if you have existing insulation, take your insulation’s measurement by measuring from the attic floor to the top of your insulation. With this information in hand, you’ll know how much more insulation you might need to improve your energy efficiency.

If you’re unsure of how much more insulation you’ll need, consult the Department of Energy’s insulation chart.

#3 Calculate 

To calculate how much insulation material to purchase, simply divide your attic’s square footage by the square footage of insulation in the manufacturer’s package (assuming you’re purchasing pre-cut batts or rolls). This will give you a rough estimate of how much insulation you’ll need and how much you can expect to pay for proper insulation.

You now have an easy and efficient attic insulation cost calculator.

Beyond Square Footage: Calculating Insulation Needs By Material

While the above calculator can give you a rough estimate of how much material you’ll need, the specific amount will vary based on the material you choose to insulate your attic or crawl space.

Though there are several different types of attic insulation, the most common include:1

  • Blanket – Made from fiberglass, natural and synthetic fibers, and mineral wool, blanket insulation comes in two forms: rolls or pre-cut panels known as batts. Inexpensive and easy to apply, blanket insulation material is perfect for spaces between joints, studs, and beams.
  • Loose-fill – Constructed from cellulose fiberglass and mineral wool, loose-fill insulation is ideal for areas that are already finished or areas with obstacles or unusual designs. Although you can install loose-fill insulation by hand, it’s most commonly installed by blowing the insulation from a blower attached to a hose. Loose-fill insulation is perfect for attics.
  • Spray foam – Similar to loose-fill insulation in that it’s perfect for attics, spray foam insulation is typically installed via small spray containers. Spray foam insulation is manufactured from various materials, including phenolic and polyurethane. 
  • Reflective – As its name implies, reflective insulation works by reflecting heat away from a home. It’s made from various materials including foil kraft paper, cardboard, and plastic film, and regulates downward heat flow exceptionally well.

These different materials also have different insulation R value types. A measurement of an insulation’s effectiveness at regulating heat flow, R-value is a useful tool when deciding between different types of insulation and the amount of insulation you’ll need. 

It’s best to consult an insulation chart to determine precise R-values and costs, but in general, materials that have lower R-values, such as blanket insulation, cost less per square foot per R-value than materials with higher R-values, such as spray foam.

Calculating R-Value

To calculate R-value, divide a material’s thickness in meters by its thermal conductivity. R-values are measured in ft. °F. h/BTU. In general, the higher a material’s R-value, the better it is at reducing heat flow.

While your R-value differs based on a number of factors, chief among these is your home’s location. For instance, while attics in the Upper Midwest and New England require insulation with R-values ranging between R49-R60, attics in the Deep South require insulation with R-values ranging between R30-R60.

Attic Construction: For When You Need The Right Measurement

Although doable, calculating your attic’s insulation takes time, energy, and money. Besides, why take the chance that your calculation is slightly off?

Fortunately, Attic Construction is here to help. By making sure your attic’s insulation requirements are met, Attic Construction’s the only attic insulation calculator you’ll need.

Schedule an appointment today to see how we can save you money on heating and cooling costs.

From attic cleaning to rodent proofing, Attic Construction is there for all of your attic needs. 



  1. U.S. Department of Energy. Guide To Insulation. https://www.energy.gov/sites/prod/files/guide_to_home_insulation.pdf


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