Duct Surface Area & Insulation Area Calculator

Surface area = perimeter × length.

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Formula

Round: π × D × L
Rectangular: 2(W + H) × L

Example calculation

8 in round × 50 ft → 104.7 ft².

Practical HVAC use

Order duct wrap or estimate sheet metal.

Common mistakes

Forgetting overlap and waste.

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Educational tool. Results are estimates from the stated formulas; always confirm with manufacturer data and the code adopted in your jurisdiction. All calculators