Hood Exhaust Calculator

Calculate required exhaust CFM for commercial kitchen hoods based on hood size, equipment duty level, and mounting configuration.

Hood Length (ft)

Hood Depth (ft)

Equipment Duty Level

Hood Mounting

Tab to move between fields

Required Exhaust (CFM)

4,800

Hood Area (sq ft)32

CFM per sq ft150

Min Duct Diameter (in)25

Est. Static Pressure (in. w.g.)2.15

Est. Fan HP2.5

How to Use This Calculator

Enter the hood length and depth in feet.
Select equipment duty level: 1 = light (ovens), 2 = medium (griddles), 3 = heavy (charbroilers), 4 = extra heavy.
Set hood mounting type: 1 = wall-mounted, 2 = island (requires about 30% more airflow).
Review the required exhaust CFM and minimum duct diameter for NFPA 96 compliance.
Use the estimated static pressure and fan HP for mechanical equipment specification.

How the result changes with Hood Length (ft)

Hood Length (ft): Length of the exhaust hood in feet.
Hood Depth (ft): Front-to-back depth (width) of the hood in feet. Standard is 4 ft for wall hoods.
Equipment Duty Level: 1 = Light (ovens, steamers), 2 = Medium (ranges, griddles), 3 = Heavy (charbroilers, fryers), 4 = Extra Heavy (wood/coal burning).
Hood Mounting: 1 = Wall-mounted (against wall), 2 = Island/exposed (open on all sides, requires ~30% more airflow).

Required Exhaust (CFM): Total exhaust airflow needed in cubic feet per minute.
Hood Area (sq ft): Hood opening area used for CFM calculation.
CFM per sq ft: Effective CFM rate per square foot of hood area.
Min Duct Diameter (in): Minimum round duct diameter for 1500 FPM duct velocity (NFPA 96).
Est. Static Pressure (in. w.g.): Estimated system static pressure for fan selection.
Est. Fan HP: Estimated exhaust fan motor horsepower.

Identify Input Parameters
4 parameters
Hood Length (ft) = 8, Hood Depth (ft) = 4, Equipment Duty Level = 2, Hood Mounting = 1 = 4 input(s) provided
Calculate Required Exhaust
Required Exhaust = ceil(requiredCfm / 50) * 50
4800 = 4800
Calculate Hood Area
Hood Area = hoodLengthFt * hoodWidthFt
32 = 32
Calculate CFM per sq ft
150 = 150