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.
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