Free Insulation Calculator
Calculate how much insulation you need in batts or rolls. Enter wall or ceiling area, stud spacing, and get the number of batts or rolls required.
sq ft
inches
93 in for 8ft walls, 105 in for 9ft walls
Batts Needed
52
Bags (Blown-In, approx)13
Coverage per Batt9.69 sq ft
Batts Needed vs Total Area to Insulate
How to Calculate Insulation
Formula
Batts Needed = Total Area / Coverage per Batt
Batt width fits between studs: 15 inches for 16" OC studs, 23 inches for 24" OC studs. Batt length is typically 93 inches (8 ft walls) or 105 inches (9 ft walls). Choose R-value based on application:
Example Calculation
500 sq ft of wall area with 16-inch OC studs, 93-inch batts, R-13.
- 01Batt width = (16 - 1) / 12 = 1.25 ft
- 02Batt length = 93 / 12 = 7.75 ft
- 03Coverage per batt = 1.25 × 7.75 = 9.69 sq ft
- 04Batts needed = 500 / 9.69 = 51.6 → 52 batts
Frequently Asked Questions
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