Range Hood CFM Calculator: Find Your Exhaust Power & Duct Size

How to Use the Calculator

Calculate your required ventilation power (CFM) and determine the exact minimum round duct pipe size needed to safely vent your kitchen.

1. Select your Stove Type (Electric or Gas) from the dropdown.
2. Enter the Total BTUs of your appliance (required only if you selected Gas).
3. Input your exact Stove Width using inches and standard fractions (e.g., 29 7/8″).
4. Enter your kitchen’s Ceiling Height in feet, inches, and standard fractions.
5. Provide the Kitchen Length in feet, inches, and standard fractions.
6. Input the Kitchen Width in feet, inches, and standard fractions.

Understanding Your Results

• Stove Baseline: For electric stoves, the math demands 100 CFM per linear foot of stove width. For gas models, it requires 1 CFM per 100 BTUs of total burner output.
• Room Volume Baseline: Your total room volume in cubic feet is divided by 4 to guarantee the system completes 15 full air exchanges per hour.
• Minimum Duct Size: Evaluates your final required CFM to assign standard rigid round duct sizing, scaling from a 6″ pipe up to a 14″ pipe for massive exhaust loads.
• Required Exhaust Power: The calculator compares both baselines and outputs the higher number, guaranteeing your hood meets whichever demand is greater.

You must purchase a range hood that meets or exceeds the Required Exhaust Power and pair it with the corresponding minimum duct pipe to ensure safe, adequate air cycling.

Tools Needed

• 25-foot tape measure (to measure stove width and room dimensions exactly)
• Stove manufacturer manual or specification plate (to locate total BTUs)

Always check local building codes and HOA guidelines before starting.

Project Overview

Sizing your kitchen ventilation requires cold hard math, not guesswork. Using our range hood CFM calculator guarantees you have the exact exhaust power to pull smoke, grease, and heat out of your house. Applying the proper CFM formula ensures your fan matches the actual heat output of your burners, whether you run a standard electric range or a high-output gas appliance. The right cooktop CFM rating keeps your cabinets clean and your indoor air safe to breathe.

This tool specifically calculates your baseline appliance ventilation requirements and assigns the correct range hood size and minimum round duct diameter. It determines the minimum exhaust power based on burner output and total room volume. You still need to account for dedicated makeup air requirements and friction loss on long or complex duct runs.

How much CFM do I need for my range hood?

You need a minimum of 100 CFM for every linear foot of an electric stove, or 1 CFM for every 100 BTUs of a gas stove. Your hood must also be powerful enough to exchange your kitchen’s entire air volume every 4 minutes.

Enter your exact appliance specifications and room dimensions into the calculator above to find your required exhaust power and minimum duct size.