Posted by Dogberry Collections
on May 12, 2026
Quick Answer: For gas ranges, a general rule is 100 CFM per 10,000 BTUs of total burner output. For electric ranges, use 100 CFM per linear foot of range width - so a 30-inch electric range needs roughly 300 CFM. Most home kitchens are well-served by a 400-600 CFM range hood.
CFM stands for cubic feet per minute - the volume of air a range hood moves each minute. Getting this number right means your hood keeps up with your cooking without being unnecessarily loud or expensive. Here is how to calculate what you actually need.
Why CFM Matters
A hood with too little CFM will not clear smoke, steam, and cooking odors before they spread through your kitchen. A hood with far too much CFM for your space can create negative air pressure, pulling air in through gaps around doors and windows and potentially causing backdrafting in gas appliances. The goal is matched capacity - enough to do the job without overdoing it.
How to Calculate CFM for a Gas Range
Add up the BTU output of all your burners. Divide by 100. That is your minimum recommended CFM.
- 4-burner range with 60,000 total BTUs: 600 CFM minimum
- 6-burner range with 90,000 total BTUs: 900 CFM minimum
- Standard residential 4-burner at 40,000 BTUs: 400 CFM minimum
If your range is against a wall, use the calculation above. If it is on an island with no walls to contain the rising air, add 25-50% to account for the open sides.
How to Calculate CFM for an Electric Range
Electric ranges generate less heat and combustion byproduct than gas, so the calculation is simpler: 100 CFM per linear foot of range width.
- 30-inch range: 300 CFM
- 36-inch range: 400 CFM
- 48-inch range: 500 CFM
Wall Mount vs. Island Hood CFM
Island hoods need more power because rising cooking vapors can escape sideways instead of being captured directly. Add 25-50% to your calculated CFM when choosing an island hood. A wall-mount hood over a 36-inch gas range needing 500 CFM would translate to a 625-750 CFM island hood for the same range.
Duct Size and CFM
High CFM hoods require larger ductwork to function properly. Undersized ducts create back pressure, reduce actual airflow, and increase noise. Common duct sizes by CFM:
| CFM Range | Minimum Round Duct | Equivalent Rectangle |
|---|---|---|
| Up to 400 CFM | 6 inch | 3.25 x 10 inch |
| 400-600 CFM | 7 inch | 3.25 x 14 inch |
| 600-900 CFM | 8 inch | 3.25 x 18 inch |
| 900+ CFM | 10 inch | 6 x 14 inch |
Ducted vs. Recirculating (Ductless) Hoods
Ducted hoods vent air outside - they remove heat, moisture, smoke, and odors. Recirculating hoods filter air through charcoal and return it to the kitchen. Recirculating hoods are easier to install (no ductwork needed) but are significantly less effective, especially for high-heat cooking. For any serious gas range, ducted ventilation is strongly preferred. Recirculating is acceptable for light cooking over electric cooktops.
Noise: Understanding Sones
Hood noise is measured in sones. A quiet conversation is about 1-2 sones. Most range hoods run between 1 sone (very quiet) and 8 sones (loud) at max speed. For a kitchen that opens to a living area, look for a hood rated below 3 sones at medium speed. High-CFM commercial-style hoods often run louder - check the spec sheet for sone ratings at each fan speed.
Browse Dogberry Collections' range hoods in wall-mount, island, and under-cabinet styles. Each listing includes CFM and sone ratings to help you find the right match for your range and kitchen layout.
