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How much R-21 insulation for 3,000 sq ft of walls?

Answer
63 batts (48 sq ft coverage each)
Total area: 3,000 sq ftR-value: R-21Coverage per batt: 48 sq ft

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How We Calculated This

Batts = ceil(Total Sq Ft / 48)

3,000 sq ft / 48 sq ft per batt = 63 batts

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Calculated using verified formulas. Last updated March 2026.