Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Insulation bags needed
40
Estimated insulation cost
$720
Attic area
1,200
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter attic area (sq ft).
- 2Enter target r-value.
- 3Enter coverage per bag at target r-value (sq ft).
- 4Enter price per bag ($).
- 5Read your insulation bags needed on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Attic insulation is typically sold in bags rated for a specific coverage area at a specific R-value, so the number of bags you need scales with both your attic's square footage and how much R-value you're adding. This calculator defaults to a 1,200 sq ft attic targeting R-38, converts that into bags based on your product's coverage rating, and estimates total material cost.
Worked example
Using the values the calculator loads with:
Inputs
- Attic area: 1200 sq ft
- Target R-value: 38
- Coverage per bag at target R-value: 30 sq ft
- Price per bag: 18 $
Results
- Insulation bags needed: 40
- Estimated insulation cost: $720
- Attic area: 1,200
What each field means
Inputs
- Attic area (sq ft)
- The attic area used in the calculation, measured in sq ft. Starts at 1200 sq ft so you have a working example on load.
- Target R-value
- The target r-value used in the calculation. Starts at 38 so you have a working example on load. Accepted range: 13–60.
- Coverage per bag at target R-value (sq ft)
- The coverage per bag at target r-value used in the calculation, measured in sq ft. Starts at 30 sq ft so you have a working example on load.
- Price per bag ($)
- The price per bag used in the calculation, measured in $. Starts at 18 $ so you have a working example on load.
Results
- Insulation bags needed
- Returned as a whole number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Estimated insulation cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Attic area
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What R-value is recommended for a 1200 sq ft attic?
Most cold and mixed climates recommend R-38 to R-60 for attics; check your local energy code or the DOE's zone recommendations for your area.
Does bag coverage change with R-value?
Yes, manufacturers list different coverage areas per bag for each target R-value since higher R-values need a thicker, denser layer — always check the bag label for your specific product.
Should I remove old insulation before adding more?
Not usually — you can typically add a new layer on top of existing insulation as long as it's dry and not compressed, which is more cost-effective than full removal.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). 1200 Sq Ft Attic Insulation Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/1200-sq-ft-attic-insulation-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/1200-sq-ft-attic-insulation-calculator" target="_blank" rel="noopener">1200 Sq Ft Attic Insulation Calculator — RevenueLab</a> (2026).</p>
Source: [1200 Sq Ft Attic Insulation Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/1200-sq-ft-attic-insulation-calculator) (2026).