Range Hood Sizing: CFM Requirements and Selection Guide

Range hood selection involves more than aesthetics. Proper sizing ensures effective smoke and odor removal while meeting code requirements.

Understanding CFM

What is CFM

• Cubic Feet per Minute
• Measures air movement volume
• Higher CFM equals more ventilation
• Must match cooking output

Why CFM Matters

• Removes cooking byproducts
• Clears smoke and steam
• Eliminates odors
• Maintains air quality
• Required for safety

Calculating CFM Requirements

Standard Formula: Range Width

• Electric range: 100 CFM per linear foot
• Gas range: 100 CFM per 10,000 BTU
• Minimum 100 CFM per foot of hood width

Professional-Style Ranges

High-BTU Requirements:

• Calculate total BTU output
• Divide by 100
• Add 100 for each additional 10,000 BTU

Example:

• 80,000 BTU total = 800 CFM minimum
• Add margin for better performance
• Consider 1,000-1,200 CFM

Island Installation

Additional Considerations:

• No wall to capture air
• Add 100-150 CFM to calculation
• Wider coverage recommended
• Height affects performance

Duct Run Impact

Long or Complex Ductwork:

• Add 25 CFM per foot of duct
• Add 25 CFM per elbow
• Longer runs need more power
• Roof caps add resistance

Hood Types

Wall-Mounted

Characteristics:

• Mounted against wall
• Most common type
• Efficient capture
• Various styles

CFM Range: 300-1,200+

Island Hoods

Characteristics:

• Suspended over island
• 360-degree exposure
• Higher CFM needed
• Design statement

CFM Range: 600-1,500+

Under-Cabinet

Characteristics:

• Mounted under cabinet
• Space-efficient
• Limited power typically
• Budget-friendly

CFM Range: 200-600

Downdraft

Characteristics:

• Rises from behind cooktop
• Low profile when not in use
• Less effective than overhead
• For islands without overhead option

CFM Range: 300-1,200

Insert/Liner Hoods

Characteristics:

• Motor unit for custom hood
• Flexible design options
• Professional installation
• Various power levels

CFM Range: 300-1,500+

Sizing by Range Type

Standard Residential Range

• 30-inch electric: 300-400 CFM
• 30-inch gas: 400-600 CFM
• 36-inch gas: 500-700 CFM

Professional-Style Range

• 30-inch pro: 600-900 CFM
• 36-inch pro: 800-1,200 CFM
• 48-inch pro: 1,000-1,500 CFM
• 60-inch pro: 1,200-1,800 CFM

Rangetops

• Higher BTU often than ranges
• Calculate based on total BTU
• Add margin for performance

Coverage Dimensions

Width

• Minimum: same as range
• Recommended: 3 inches wider per side
• Professional: 6 inches wider per side

Depth

• Should cover all burners
• Front burners critical
• 20-24 inches typical

Height Above Range

• Electric: 24-30 inches
• Gas: 30-36 inches
• Check code requirements
• Higher mounting reduces effectiveness

Makeup Air Considerations

When Required

• Generally above 400-600 CFM
• Local codes vary
• Tight homes need more
• Required for proper function

Makeup Air Options

• Passive dampers
• Powered makeup air systems
• HVAC integrated systems
• Must balance exhaust

Symptoms Without Makeup Air

• Door slamming
• Backdrafting
• Hood whistling
• Poor exhaust performance

Noise Considerations

Sone Ratings

• Lower sones = quieter
• 1-3 sones: quiet
• 4-6 sones: moderate
• 7+ sones: loud

Reducing Noise

• External blowers
• Larger diameter duct
• Shorter duct runs
• Inline silencers

Code Requirements

Typical Requirements

• Minimum ventilation rates
• Duct material specifications
• Fire safety requirements
• Makeup air provisions

Permits

• Often required for installation
• Especially with makeup air
• Check local requirements
• Professional install recommended

Brand Considerations

For Wolf Ranges

• Wolf ventilation recommended
• Sized for BTU output
• Matched performance

For Viking Ranges

• Viking Professional hoods available
• High CFM options
• Commercial styling

For Thermador Ranges

• Thermador ventilation line
• Integrated options
• Home Connect compatible

Selection Checklist

1. Calculate CFM needed
2. Determine hood type
3. Size width and depth
4. Consider ductwork
5. Plan makeup air
6. Check noise ratings
7. Verify code compliance
8. Budget appropriately

Conclusion

Proper range hood sizing ensures effective kitchen ventilation and safe operation of your cooking equipment. Calculate CFM based on your range type and BTU output, factor in ductwork and installation variables, and do not forget makeup air requirements. Working with a professional ensures proper sizing and installation for your specific kitchen configuration.