Insulation Calculator
Calculate the number of insulation batts or rolls needed for wall cavities. Supports standard and custom batt sizes.
Formula & Explanation
This calculator determines the number of insulation batts or rolls required to fill wall cavities. **Batts Needed** = ceil(Wall Area ÷ Batt Size) Standard batt and roll sizes include: - **16" × 48"**: 6.67 square feet (common for 16" o.c. framing) - **24" × 48"**: 8 square feet (common for 24" o.c. framing) - **16" × 93"**: 10.3 square feet (full-height for standard 8 ft walls) - **24" × 93"**: 15.5 square feet The ceiling function ensures you round up, because partial batts still require a full purchase.
Assumptions
- •Batt dimensions and coverage areas (6.67, 8, 10.3, 15.5 sqft) are standard product sizes; verify with manufacturer
- •Batt R-value (R-3.2 per inch) varies by product type (fiberglass, mineral wool, spray foam)
- •Calculator assumes batts fit cavities fully; does not account for waste, sealing, or compression
- •Wall area should be the net area of cavities to be insulated (gross wall minus openings)
- •Does not include vapor barriers, air sealing materials, or installation labor
Example Calculation
A 320 sqft wall insulated with 16×93 batts (10.3 sqft each) requires approximately 31 batts.
Inputs
Results
Batts Needed by Wall Area and Batt Size
| wall_area_sqft | 16×48 (6.67) | 24×48 (8) | 16×93 (10.3) | 24×93 (15.5) |
|---|---|---|---|---|
| 100 | 15 | 13 | 10 | 7 |
| 200 | 30 | 25 | 20 | 13 |
| 320 | 48 | 40 | 31 | 21 |
| 500 | 75 | 63 | 49 | 33 |
Frequently Asked Questions
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