Duct Surface Area Calculator
Total surface area of a duct run.
Enter your values
ⓘ Live results
Results
- Perimeter
- 31.4 in
- Total surface area
- 65.4 sq ft
- Insulation needed (with 10% waste)
- 72 sq ft
Quick answer
Duct surface area equals the perimeter of the cross-section multiplied by the duct's length.
Surface area = perimeter x length
How to use the Duct Surface Area Calculator
- 1Choose round or rectangular duct and enter its dimensions.
- 2Enter the total length of the duct run.
- 3Use the surface area for insulation wrap, mastic sealant coverage or sheet metal takeoff.
Worked example
Using the values the calculator loads with:
Inputs
- Duct shapeRound
- Diameter or width10 in
- Height (rectangular only)8 in
- Duct length25 ft
Results
- Perimeter31.4 in
- Total surface area65.4 sq ft
- Insulation needed (with 10% waste)72 sq ft
Frequently asked questions
Why add a waste factor?
Overlaps, offcuts and fitting transitions typically consume 5-15% extra insulation material.
Does this include both ends?
No, this is just the lateral (side) surface area of the duct barrel, not the end caps.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.