Choosing the right commercial kitchen hood is about much more than measuring the length of your restaurant's cooking equipment.
A hood that is too small may not properly capture smoke, grease, heat, and cooking vapors. A hood that is unnecessarily large can increase equipment, installation, ductwork, exhaust, and makeup-air costs.
So how do you determine what size hood your commercial kitchen actually needs?
Start with the equipment that will be installed underneath the hood. Add up the width of the cooking equipment, determine what type of cooking each appliance performs, account for the hood's required capture area, and then make sure the exhaust system is designed for the cooking load.
The important thing to understand is that hood length and exhaust capacity are not the same thing. Two restaurants could both have a 10-foot hood but require very different exhaust systems depending on the equipment underneath them.
Start With Your Cooking Equipment
Before choosing a hood, create a complete list of every appliance that will be located on the cooking line.
This might include:
- Commercial ranges
- Deep fryers
- Griddles
- Charbroilers
- Stock pot ranges
- Wok ranges
- Tandoors
- Convection ovens
- Combi ovens
- Steam equipment
Do not design the hood first and then try to squeeze your equipment underneath it.
Ideally, the cooking line and ventilation system should be planned together.
Add Up the Width of Your Cooking Equipment
The easiest starting point is determining the total width of everything that will sit underneath the hood.
For example, suppose your cook line includes:
- 36-inch commercial range
- 36-inch griddle
- Two 18-inch fryers
- 24-inch charbroiler
The total equipment width would be:
36 + 36 + 18 + 18 + 24 = 132 inches
That equals:
11 feet of cooking equipment.
However, this does not automatically mean you should order an 11-foot hood.
Your Hood Usually Needs to Extend Beyond the Cooking Equipment
A commercial kitchen hood needs enough coverage to capture the cooking plume as heat, grease, smoke, and steam rise from the equipment.
Cooking emissions do not travel perfectly straight upward. They can spread outward as they rise.
For that reason, traditional canopy hoods generally extend beyond the active cooking surfaces on exposed sides.
The exact amount of overhang depends on the hood design, equipment arrangement, hood listing, installation conditions, and local mechanical code.
This means an 11-foot cooking line could require a hood longer than 11 feet.
A Simple Hood Length Example
Suppose your cooking equipment occupies 10 feet from left to right.
If the approved hood configuration requires additional capture area at each exposed end, you need to account for that space when choosing the hood.
Your calculation is therefore closer to:
Total equipment width + required end coverage = minimum hood length
Do not simply purchase a hood that is exactly the same width as the equipment line without checking the hood manufacturer's requirements and the applicable code.
Measure the Depth of the Equipment Too
Length is only one dimension.
Commercial cooking equipment can vary significantly in depth.
A range, fryer, griddle, and countertop charbroiler may all sit differently underneath the same canopy.
Measure:
- Overall appliance depth
- Location of the actual cooking surface
- Control-panel projection
- Handles and doors
- Required rear clearance
The active cooking surface needs to remain inside the hood's intended capture area.
A piece of equipment may technically fit from left to right while extending too far forward for the hood to capture its cooking plume properly.
Know the Difference Between a Type I and Type II Hood
Before determining hood size, you also need to determine what type of hood the kitchen requires.
Type I Hood
A Type I commercial hood is generally used over cooking equipment that produces grease, smoke, or grease-laden cooking vapors.
Common equipment may include:
- Deep fryers
- Charbroilers
- Griddles used for grease-producing foods
- Ranges
- Wok ranges
- Other grease-producing cooking equipment
For example, if your restaurant uses multiple commercial deep fryers and a commercial charbroiler, ventilation requirements may be substantially different from a kitchen primarily reheating or steaming food.
Type II Hood
Type II hoods are generally designed for applications involving heat, steam, moisture, or condensation without grease-laden exhaust.
The equipment and cooking process ultimately determine the appropriate system.
The Equipment Producing the Most Exhaust Matters
Not every appliance creates the same ventilation load.
There is a major difference between boiling water and charbroiling fatty meat over intense heat.
Equipment may be classified into different cooking-duty categories when the ventilation system is engineered.
Higher-duty appliances generally create more:
- Heat
- Smoke
- Grease
- Cooking vapors
- Air movement
That can increase the exhaust required from the hood.
A Charbroiler Can Change Your Hood Requirements
Charbroilers are particularly important when designing restaurant ventilation.
A restaurant grilling burgers, steaks, chicken, kebabs, or other proteins may produce much more smoke and grease than a restaurant primarily using burners for soups and sauces.
This means adding a commercial charbroiler to a planned cook line can affect the ventilation design even if it only occupies another 24 or 36 inches of physical space.
Do not evaluate hood requirements based only on appliance width.
Deep Fryers Also Need Proper Ventilation
Commercial fryers produce heat and grease-laden cooking emissions and are typically installed beneath an appropriate Type I system.
If your kitchen uses several commercial fryers, they need to be included when the hood designer calculates both physical coverage and exhaust requirements.
This is particularly important for restaurants producing large volumes of fried food throughout the day.
Ranges Need to Be Included in the Cooking Line
A commercial restaurant range can occupy anywhere from a relatively small section of the cook line to five feet or more depending on the number of burners and configuration.
When choosing your range, think about the hood at the same time.
For example:
- A 24-inch four-burner range uses relatively little line space.
- A 36-inch six-burner range requires more.
- A 48-inch eight-burner range takes another foot.
- A 60-inch ten-burner range can occupy a major portion of the hood by itself.
A larger range may give your cooks additional capacity, but it also consumes valuable hood space.
Griddle Size Can Quickly Increase Hood Length
Commercial griddles are commonly available in widths such as:
- 24 inches
- 36 inches
- 48 inches
- 60 inches
- 72 inches
A restaurant serving breakfast, burgers, cheesesteaks, dosa, paratha, or other high-volume griddled items might dedicate several feet of its cook line to a commercial griddle.
Consider your actual peak production requirements before choosing an oversized griddle that consumes unnecessary hood space.
Stock Pot Ranges Need to Be Planned Differently
A commercial stock pot range is usually much lower than a conventional restaurant range.
However, the pot sitting on top may be extremely large.
When planning hood coverage around a stock pot range, think about the complete working setup, including:
- Burner height
- Pot height
- Pot diameter
- Steam production
- Working space needed to stir the pot
- Ability to safely remove the lid
Restaurants producing large batches of stock, curry, sauce, biryani, soup, or other bulk foods should plan this station carefully.
What About Commercial Tandoors?
Tandoors require additional consideration because they cook through an opening at the top rather than on a conventional horizontal cooktop.
When planning ventilation for a commercial tandoor, account for:
- Tandoor width
- Tandoor depth
- Total height
- Height of the top opening
- Fuel type
- Cooking process
- Clearance above the opening
- Hood capture area
The hood and fire-protection design should be reviewed for the specific tandoor and installation rather than treating it exactly like a conventional range.
Hood Size Does Not Tell You the Required CFM
This is one of the most important things to understand about commercial kitchen ventilation.
A 10-foot hood does not automatically require one specific CFM.
CFM stands for cubic feet per minute and represents the amount of air the exhaust system moves.
The required airflow can depend on:
- Hood style
- Hood length
- Appliance duty
- Cooking process
- Equipment positioning
- Whether the hood is against a wall or over an island
- Hood manufacturer's listing
- Local mechanical-code requirements
Two restaurants with identical hood dimensions could therefore have different exhaust requirements.
Wall Canopy vs. Island Hood
Hood configuration also matters.
Wall Canopy Hood
A wall canopy hood is installed against a wall with the cooking equipment underneath it.
This is one of the most common restaurant hood arrangements.
The wall helps contain the cooking plume on one side.
Island Hood
An island hood is installed over equipment located away from a wall.
Because the cooking plume can move in more directions, an island system may require a different capture area or airflow design.
Do not assume that an 8-foot wall hood and an 8-foot island hood will perform identically.
Do Not Forget Makeup Air
If your kitchen exhausts thousands of cubic feet of air every minute, replacement air has to enter the building.
This is called makeup air.
An improperly balanced kitchen can experience problems such as:
- Doors that are difficult to open
- Strong drafts
- Uncomfortable dining rooms
- Heating and cooling problems
- Cooking smoke escaping the hood
- Pressure problems throughout the building
That is why commercial hood design involves more than simply selecting a stainless steel canopy and exhaust fan.
The hood, exhaust fan, ductwork, makeup-air system, HVAC system, and cooking equipment all work together.
Fire Suppression Is Part of the Hood Planning Process
A Type I commercial cooking system also needs to be considered together with the required fire-protection system.
The location and type of appliances underneath the hood matter.
For example, changing a cooking line from:
Range | Fryer | Griddle
to:
Fryer | Fryer | Charbroiler
may keep the total equipment width nearly the same while significantly changing the cooking hazards.
This is why restaurants should not freely move equipment underneath an existing hood without checking how the change affects the ventilation and fire-suppression system.
Can You Fill the Entire Hood With Equipment?
Usually, maximizing every inch underneath the hood should not be the goal.
Your cook line also needs usable working space.
Think about:
- Prep and landing areas
- Access for cleaning
- Equipment servicing
- Oven-door clearance
- Fryer basket movement
- Large pot handling
- Employee movement
Installing another appliance simply because there appears to be 18 inches of unused hood space can sometimes make the kitchen less efficient rather than more productive.
Example: Planning a 12-Foot Cooking Line
Imagine a restaurant plans to install:
- 36-inch six-burner range
- 36-inch griddle
- Two 18-inch fryers
- 36-inch charbroiler
Total equipment width:
36 + 36 + 18 + 18 + 36 = 144 inches
That equals exactly:
12 feet.
It would be a mistake to automatically order a 12-foot hood.
The hood designer still needs to consider:
- Required capture beyond the cooking surfaces
- Equipment depth
- Cooking duty
- Required exhaust airflow
- Makeup air
- Fire suppression
- Duct routing
- Fan placement
- Manufacturer specifications
- Local code requirements
The final hood may therefore need to be longer than the physical cooking line.
Should You Make the Hood Bigger for Future Equipment?
If you expect the restaurant to grow, it may make sense to plan some additional cooking capacity from the beginning.
Installing a larger hood during the original buildout can sometimes be easier than extending or replacing the ventilation system later.
However, bigger is not automatically better.
A larger hood may affect:
- Purchase cost
- Duct size
- Fan capacity
- Makeup-air requirements
- Heating and cooling loads
- Fire-suppression design
- Installation cost
Plan for realistic growth rather than adding several feet of unused hood simply because you might someday purchase additional equipment.
How to Size a Hood for an Existing Restaurant
If the hood is already installed, reverse the process.
Measure:
- Total hood length
- Hood depth
- Mounting height
- Available equipment space
- Existing exhaust airflow
- Makeup-air configuration
Then find the hood's manufacturer and model information if possible.
Original plans may also show:
- Approved equipment layout
- Exhaust CFM
- Makeup-air CFM
- Duct dimensions
- Fire-suppression layout
Do not assume that any appliance that physically fits underneath an existing hood can automatically be added.
A Simple Commercial Hood Planning Formula
For the physical hood length, start with:
Total width of cooking equipment + required capture area on exposed sides = approximate hood length
Then verify:
- Equipment depth
- Cooking-surface location
- Hood type
- Appliance duty
- Required CFM
- Makeup air
- Fire suppression
- Ductwork
- Clearances
- Manufacturer listing
- Local code
This is why hood sizing should not be reduced to one simple dimension.
Common Commercial Kitchen Hood Sizing Mistakes
Avoid these common mistakes when planning your restaurant kitchen:
- Buying a hood before choosing the cooking equipment
- Making the hood exactly the same width as the appliances
- Ignoring equipment depth
- Ignoring cooking-surface height
- Assuming every appliance requires the same exhaust airflow
- Adding a charbroiler or fryer without reviewing the existing system
- Forgetting makeup air
- Changing appliance positions without reviewing fire suppression
- Filling every inch beneath the hood with equipment
- Assuming more CFM is always better
- Ignoring future menu changes
How Big of a Hood Does Your Restaurant Need?
Your commercial kitchen hood should be sized around the cooking equipment and cooking processes underneath it, not simply the size of the kitchen.
Begin by laying out your entire cook line. Add up the equipment widths and determine how much capture area the approved hood configuration requires around those appliances.
Then evaluate the appliances themselves.
A range, griddle, fryer, charbroiler, wok range, and tandoor can create very different ventilation demands even when they occupy similar amounts of floor space.
Finally, make sure the hood's exhaust airflow, ductwork, makeup air, fire suppression, clearances, and installation comply with the hood manufacturer's specifications and the requirements of your local authority having jurisdiction.
If you are building or upgrading a restaurant kitchen, Nishi Enterprise carries commercial ranges, deep fryers, commercial griddles, charbroilers, stock pot ranges, and commercial tandoors for complete restaurant cooking lines.
Frequently Asked Questions
How much bigger should a commercial hood be than the cooking equipment?
A canopy hood generally needs to extend beyond the active cooking surfaces on exposed sides. The required amount depends on the hood style, listing, installation, and applicable mechanical code, so do not assume the hood can be exactly the same width as the equipment.
Does a bigger commercial kitchen hood need more CFM?
Hood length affects airflow requirements, but it is not the only factor. Hood style, cooking duty, appliance type, mounting conditions, and manufacturer listing can all affect the required exhaust airflow.
Do commercial fryers need to be under a hood?
Commercial frying generally produces grease-laden cooking emissions and commonly requires an appropriate Type I exhaust system. The requirements for a specific installation should be confirmed with the equipment specifications and local authority.
Does a commercial charbroiler require more ventilation than a range?
A charbroiler can create significant heat, smoke, and grease, particularly when cooking fatty proteins. The hood system should therefore be designed around the specific equipment lineup rather than assuming all appliances create the same ventilation load.
Can I add more restaurant equipment under my existing hood?
Possibly, but available physical space is only one consideration. Check hood coverage, exhaust capacity, appliance duty, fire-suppression coverage, gas or electrical capacity, equipment clearances, and the original hood design before making changes.
Should I buy my hood before my restaurant equipment?
It is generally better to establish the cooking equipment lineup first or design the equipment and ventilation together. The hood needs to be appropriate for the size, position, and cooking duty of the appliances it serves.
