Duct Insulation Calculator

Insulation R-value and material for HVAC ductwork.

Duct diameter (or width)

Total duct length

Duct shape

Supply air temperature

°F

Ambient temperature

°F

Insulation R-value

Tab to move between fields

Heat loss (insulated)

1,676 BTU/hr

Est. annual savings vs bare

$179.00

≈ 12 movie tickets

Duct surface area157.1 sq ft

Heat loss (bare)8,378 BTU/hr

Heat loss reduction80%

Temp drop per 100 ft5.6 °F

Insulation material needed173 sq ft

How to Use This Calculator

Enter Duct diameter (or width), Total duct length, and Duct shape.
Set Round, Rectangular, and Supply air temperature.
Adjust Ambient temperature, Insulation R-value as needed.
Review Heat loss (insulated) (BTU/hr) and Est. annual savings vs bare ($).
Use Duct surface area (sq ft) and Heat loss (bare) (BTU/hr) to inform your decision.

How the result changes with Supply air temperature

Duct diameter (or width): Diameter for round ducts or width for rectangular ducts.
Total duct length: Total length of ductwork in unconditioned space (attic, crawl, garage).
Duct shape: Shape of ductwork cross-section.
Supply air temperature: Temperature of conditioned air inside the duct.
Ambient temperature: Temperature of the unconditioned space surrounding the duct.
Insulation R-value: R-value of duct insulation wrap or board.

Duct surface area: Total exterior surface area of ductwork.
Heat loss (insulated): Heat loss through insulated ductwork per hour.
Heat loss (bare): Heat loss without insulation for comparison.
Heat loss reduction: Percentage reduction in heat loss from insulation.
Temp drop per 100 ft: Approximate air temperature drop per 100 feet of duct run.
Insulation material needed: Duct wrap/board needed including 10% waste.
Est. annual savings vs bare: Estimated annual energy cost savings compared to uninsulated duct.

Identify Input Parameters
4 parameters
Duct diameter (or width) = 12, Total duct length = 50, Duct shape = 0, Supply air temperature = 120 = 6 input(s) provided
Calculate Heat loss
Heat loss = uValue * ductSurfaceArea * deltaT
1676 = 1676
Calculate Est. annual savings vs bare
179 = $179
Calculate Duct surface area
Duct surface area
157.1 = 157.1
Calculate Heat loss
Heat loss = uBare * ductSurfaceArea * deltaT
8378 = 8378