Free Calculator
How Much Insulation Do I Need? (Florida Attic Calculator)
Find your recommended R-value, how many inches of insulation to add, and how many bags of blown-in fiberglass your Florida attic needs.
Total conditioned square footage (from your listing or tax record).
Recommended for your Florida attic
R-38
Your home was likely built to about R-19. To reach R-38 you'd add ~5.4″ of new insulation (about 15″ total depth).
Estimates are for planning only and based on typical Central Florida homes and 2026 pricing for blown-in fiberglass. Your exact price depends on attic access, existing insulation condition, and whether removal is needed — confirmed free during your inspection.
"How much insulation do I need?" comes down to three numbers: your target R-value, how much you already have, and your attic's size. This calculator works out all three for a Florida attic and tells you exactly how much new material it takes to reach the R-38 standard.
Insulation is measured in R-value (resistance to heat flow), and how many inches that takes depends on the material: blown fiberglass runs about R-2.2–2.7 per inch (so R-38 is roughly 13–16 inches), while cellulose (~R-3.5/in) and spray foam reach R-38 at less depth. If your attic already has usable insulation, you only top it off to reach R-38.
What goes into this estimate
Target R-value. Florida attics should reach R-38. That's the number this tool sizes toward.
Your current R-value. Estimated from your home's age — homes built before 1990 were often insulated to R-19 or less.
Depth to add. The difference between R-38 and your current level, converted to inches of new blown-in fiberglass.
Bags of material. Based on your attic footprint and coverage per bag at the depth you need.
Frequently asked questions
How many inches of insulation do I need in a Florida attic?
To reach R-38 from bare: about 13–16 inches of blown fiberglass, ~11 inches of cellulose, or ~6 inches of closed-cell spray foam. If you already have some insulation, you only add the difference.
How do I know how much insulation I already have?
Measure the depth at the attic floor with a ruler. Blown-in fiberglass gives roughly R-2.5 per inch, so 6 inches ≈ R-15. Or use your home's build year as an estimate — this tool does that for you.
How many bags of blown-in insulation do I need?
It depends on your attic square footage and the depth to add. A typical 2,000 sq ft Florida home needs roughly 40–70 bags to reach R-38 — the calculator gives your exact estimate.
Popular guides & calculators
Free Florida attic resources — real answers, no email required.
The Complete Florida Attic Insulation Guide
Everything Florida homeowners need to know about attic insulation — R-values, materials, cost, savings, moisture, rebates, and how to choose.
Complete Florida Attic Insulation Cost Guide
What attic insulation really costs in Florida, what drives the price, and cost by material and home size.
Complete Guide to R-38 Insulation in Florida
Why R-38 is the Florida attic standard, how deep it is in each material, and what it takes to reach it.
Complete Guide to Blown-In Fiberglass Insulation
How blown-in fiberglass works, its R-value per inch, coverage, cost, and how it compares to other materials.
Complete Guide to Attic Insulation Removal
When to remove old insulation versus top off, how removal works, and what it costs in Florida.
Complete Guide to Attic Insulation for Older Florida Homes
Why older Florida homes are under-insulated and how to upgrade them safely.