What Is an Attic Insulation Calculator?

attic insulation cost calculator

An energy-efficient home doesn’t just reduce your energy bills: It can increase your comfort levels during the summer and winter months. One of the best ways to make your home energy-efficient is to install attic insulation or beef up your existing insulation.

The cost of attic insulation will vary from one property to the other. To get a definite project cost, you’ll need to use an attic insulation calculator.

However, you can expect to spend around $1,500-$4,500 on your attic insulation project. The installation cost will be lower for attics with smaller square footage and those with some insulation.

What Is an Attic Insulation Calculator?

An attic insulation cost calculator is a formula that provides you with an answer on how much insulation you need to properly insulate your attic. The formula considers factors like the size of your attic and your current insulation levels.

You can complete the calculation on your own or get help from any online attic insulation savings calculator with the formula already coded into an interface.

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Steps to Calculate Insulation Costs

Here’s how you can calculate the cost of your attic insulation:

Measure the Attic

It’s easier to measure square or rectangular attic spaces. You just need to measure the attic’s width and length and multiply both figures to arrive at your home’s square footage. For triangular attics, you’ll need to measure the triangle’s height and width and divide the base in half.

The total sum you arrive at when you multiply the triangle’s height and base will give you the square footage of the area.

Measure Current Insulation Levels

If you already have some insulation in your attic, measure it to determine how much more you need. You can skip this step if the attic has no insulation.

To get the total, measure from the attic floor to the top of your insulation. Armed with this information, you can see how much more insulation you need to complete your attic insulation project.


If you’re buying pre-cut rolls and batts, finding out the cost of your insulation is more straightforward. Divide your attic’s square footage by the square footage metric on the manufacturer’s packaging. You will arrive at the projected total cost for the entire insulation project.

A good tip is to give yourself some wiggle room when using this attic insulation calculator for attic spaces. Add 10% of the total cost to the final calculation to ensure you won’t need to return to the home improvement store.

Calculating Insulation Needs By Material

The attic insulation calculator above will bring you closer to the total amount you will need to spend on your attic insulation. However, you can’t put a pin on the figure if you don’t know the insulation material you’d like to use.

Your choice of insulation material will influence the final cost of the project. The various materials have different R-values (a measure of how well the material can resist heat loss or heat gain). If you use an online attic insulation energy savings calculator, you’ll have to select your choice of insulation material as one of the inputs.

Some of the top options include the following:

Insulation Blanket

The blankets consist of mineral wool and synthetic or natural fiber, and you can buy them in rolls or batts. This is the type of insulation material you’ll get when you ask for fiberglass batts. They are popular, inexpensive options that fit nicely between beams, studs, and joints.

Spray Foam Insulation

Spray foam insulation is a product of various chemicals, including polyurethane and phenolic. This option works well for an attic space because the material can reach into crevices and tight compartments.

Loose-Fill Insulation

This insulation material features mineral wool and cellulose fiberglass and is the perfect choice for an already-finished attic. Most installers use a blower during the installation, but you can also install the material by hand.

Reflective Insulation

This insulation material works by reflecting heat away from your home. It often consists of materials like cardboard, plastic film, and kraft paper, and it is highly effective at regulating downward heat flow.

These materials have different R-values. You can expect to spend more per square foot on materials with higher R-values, like spray foam and loose-fill, compared to others with lower R-values, such as fiberglass batts.

Calculating R-Value

As mentioned above, the R-value measures a material’s heat conduction. The measurement metric is “ft. °F. h/BTU.” To calculate the R-value for a material, divide its thickness by its documented thermal conductivity. Materials that have higher R-values are better at reducing heat flow overall.

You should choose materials that will help you reach the Department of Energy’s recommended R-value target for your area. People living in Los Angeles should aim for insulation with R-values between R30-R60.

You can also use this R-value calculator to find definitive results for your situation.

Frequently Asked Questions (FAQs) – Attic Insulation Calculator

What R-Value Do I Need for the Attic?

The minimum R-value for the attic in warmer regions like Los Angeles is R30, and the maximum is R60. Achieving R-values above R60 in this zone is unnecessary. However, if you move to colder zones, you should aim for R49 as the barest minimum. R49 is the upper boundary for attic insulation in areas hotter than Los Angeles.

Do Attic Insulation Costs Vary from Region to Region?

Attic insulation costs vary from region to region because different zones have different R-value requirements.

The materials you’ll need while living in a zone seven location on the Department of Energy R-value scale will differ from what you’ll need in zone one. You can also expect the cost of labor to change based on this scale.


You must consider many things when insulating your attic—cost being chief among them. Using a spray foam or cellulose attic insulation calculator will give you a close estimate of what you can expect the project to cost.

Contact Attic Projects today for guidance, definitive price estimates, and professional installation.