Grease Duct Design Calculator

Size grease exhaust ductwork based on CFM, run length, and NFPA 96 code requirements for velocity, material, and cleanout spacing.

Exhaust CFM

Duct Run Length (ft)

Number of Elbows

Duct Material

Tab to move between fields

Round Duct Diameter (in)

Rectangular Width (in)8

Rectangular Height (in)30

Duct Velocity (FPM)1,698

Cleanout Openings6

Est. Static Pressure (in. w.g.)4.4

Est. Duct Weight (lbs)263

Rect Side15.49

Gauge Label18 ga Stainless Steel

How to Use This Calculator

Enter the total exhaust CFM from the hood.
Set the total duct run length in feet and the number of 90-degree elbows.
Select duct material: 1 = carbon steel, 2 = stainless steel.
Review the recommended round duct diameter and verify velocity is within NFPA 96 range of 1,500-2,500 FPM.
Use the cleanout count and estimated static pressure for code compliance and fan sizing.

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