How Much CFM Do I Need For A Kitchen Range Hood? | Right-Size Guide

This guide gives clear formulas, quick checks, and real-world tweaks so you can match airflow to your stove, layout, and habits without guesswork. Many readers type “how much cfm do i need for a kitchen range hood?”—you’ll get a straight, workable path here.

Quick Answer: Range Hood CFM Rules That Work

Two baseline methods cover almost every home setup. Pick the one that fits your cooktop and fuel type, then refine it with the adjustments below.

• Width rule (electric/induction or light gas): 100 CFM per linear foot of cooktop when the hood is on a wall. Island hoods need more capture, so bump the target by about 50%.
• BTU rule (gas): Add up the burner output in BTUs and divide by 100 to get a minimum CFM.

Table 1: Fast Sizing By Common Setups

The table below compresses typical cases. Choose the row that mirrors your kitchen, then tune as needed in the sections that follow.

Cooktop & Layout	How To Size	Target CFM
30" electric on a wall	Width rule: 2.5 ft × 100	≈ 250 CFM
36" electric on a wall	Width rule: 3.0 ft × 100	≈ 300 CFM
30" island (electric)	Width rule × 1.5	≈ 375 CFM
36" island (electric)	Width rule × 1.5	≈ 450 CFM
Gas range, 40,000 BTU	BTU ÷ 100	≈ 400 CFM
Gas range, 60,000 BTU	BTU ÷ 100	≈ 600 CFM
Pro-style gas, 90,000 BTU	BTU ÷ 100	≈ 900 CFM
Griddle/wok routine	Start with BTU rule	+100–200 CFM

Why These Formulas Match Real Kitchens

Range hoods move air in cubic feet per minute (CFM). The goal is capture at the front and sides of the plume, not just raw fan power. The Home Ventilating Institute backs a simple approach: size by cooktop width for wall setups, and use more pull over an island where smoke can drift.

Gas adds heat and moisture fast, so the BTU rule gives a clean baseline. Both methods align with common local exhaust guidance near a 100 CFM floor for any ducted hood.

How Much CFM Do I Need For A Kitchen Range Hood? (Full Walkthrough)

Let’s run the math end-to-end for the two common scenarios, then dial in adjustments for ducting, height, and cooking style. If you’re asking “how much cfm do i need for a kitchen range hood?”, the steps below give you the exact moves.

Step 1: Pick Your Base Method

Electric Or Induction On A Wall

Measure width in feet and multiply by 100. That covers simmering, boiling, and light searing with a hood that sits on the wall.

Island Layout

Start with the width rule, then add about 50%. An island has no back wall to corral the plume, so extra flow raises capture and keeps smoke from spilling.

Gas Range

Total the burner ratings on the data plate or spec sheet. Divide by 100 to set your minimum. A 50,000 BTU range points to ~500 CFM before any tweaks.

Step 2: Check Hood Size And Mount Height

Match hood width to the cooktop, and if space allows, let the canopy overhang the cooktop by 1–3 inches on each side. Mount height lands in a common band of 20–30 inches above the surface, per many makers. Wider canopies and correct height improve capture at the same CFM, which keeps noise down.

Step 3: Adjust For Real-World Factors

Use these adders when your setup adds resistance or your cooking throws heavier plumes.

• Long duct runs or many elbows: add 50–150 CFM.
• Small round duct (less than 6"): move up a model or enlarge the duct.
• Charcoal recirculation kit: not a substitute for outdoor venting; size as if ducted, but expect lower capture.
• Daily high-heat searing, wok, or deep frying: add 100–200 CFM.
• Downdraft systems: need more flow than a canopy in the same kitchen; many users step up 200+ CFM.

Code Notes: Makeup Air And Minimum Performance

Many local codes track the International Residential Code. When a kitchen exhaust can pull more than 400 CFM, a dedicated makeup air path is typically required so the house doesn’t go into deep negative pressure. If you plan for 600–1200 CFM, budget for a makeup air kit and an interlocked damper.

There is also a baseline for local exhaust performance from residential ventilation standards. A ducted hood that can deliver around 100 CFM meets that basic threshold, but real cooking needs often point higher.

You can read more in the official sources here: the IRC section on makeup air and HVI’s primer on how to size ventilation.

CFM Targets By Cooking Habits

Airflow needs swing with how you cook. Use the guide below to set fan power that fits your routine.

• Boiling and oven baking: 250–350 CFM on a 30" wall setup, 350–450 CFM on an island.
• Daily sauté and searing: 350–500 CFM on a 30" wall setup, 500–650 CFM on an island.
• Frequent stir-fry, griddle, or indoor grilling: 600–900 CFM based on BTU totals and duct limits.

Keep Noise Manageable While You Add CFM

Look for a blower with multiple speeds. Run a lower speed for simmer duty and a boost for smoky bursts. Sone ratings around 1–3 at working speeds feel fine. Remote blowers move sound away from the room.

Match Ductwork To The Fan

Airflow ratings assume proper ducts. Keep runs short and smooth. Use rigid metal, sealed joints, and avoid tight elbows off the outlet. Many makers want 6″ round duct for 300–400 CFM and 8–10″ for 600–1200 CFM.

Table 2: Typical Duct Sizes And Practical CFM Ceilings

Duct Size	Common Hood Class	Practical Max CFM*
6" round	250–400 CFM under-cabinet or wall	≈ 350–400
7" round	350–500 CFM wall	≈ 450–550
8" round	600–800 CFM wall or island	≈ 700–850
10" round	900–1200 CFM pro-style	≈ 1000–1200
3.25" × 10" rectangular	250–400 CFM under-cabinet	≈ 300–350
4" × 10" rectangular	400–600 CFM wall	≈ 500–600
Makeup air present	Over 400 CFM systems	Balanced flow

*Assumes short runs with two gentle elbows. Long or rough ducts need derating.

Wall Mount Vs Island: What Changes

Wall mounts benefit from the back wall and need less airflow. Islands sit in open air; add CFM, widen the hood, or drop the mount height within the maker’s range.

Recirculating Hoods: When Ducting Outside Isn’t In The Cards

A recirculating kit uses a charcoal filter and sends air back into the room. Grease removal works and odors improve, but water vapor and heat stay inside. If you must go ductless, choose strong capture and fresh filters. Where code asks for local exhaust, a ducted hood meets that ask.

Makeup Air: Plan Before You Order A 600–1200 CFM Hood

Strong exhaust can back-draft chimneys and starve gas appliances. Many codes trigger a makeup air requirement at 400 CFM. The typical fix is a motorized damper tied to the hood so fresh air opens when the fan runs.

Common Mistakes That Hurt Capture

• Picking a narrow hood that matches cabinet lines but not the cooktop.
• Mounting too high, which lets the plume spread before the fan can catch it.
• Running long flex duct with tight bends.
• Buying a 900 CFM hood, then necking the outlet down to 6 inches.
• Skipping a makeup air plan on big systems.

Worked Examples Using Both Methods

Example 1: 30" Induction On A Wall

Width rule gives 2.5 × 100 = 250 CFM. Short 6" duct, two gentle elbows, light sauté a few nights a week. A 300–350 CFM hood with a wide canopy and a quiet low speed will feel smooth and clean.

Example 2: 36" Island With Daily Searing

Base width is 3.0 × 100 = 300. Island bump ×1.5 gives ~450. Add 150 CFM for pan smoke and a longer run. Target lands near 600–650 CFM with an 8" duct and a deep canopy.

Example 3: Gas Range Rated 60,000 BTU

BTU rule sets a 600 CFM floor. The duct leaves the top of the hood, turns once, then shoots outside. Family loves wok night twice a week. A 700–800 CFM hood sized 36"–42" wide keeps haze down without blasting your ears on weeknights.

When To Step Up A Size

Move up if you often use front burners for high heat, if you have a tall cook, or if the hood must sit at the top of the mounting range. A slightly stronger blower gives headroom so you don’t run max speed all the time.

Checklist Before You Buy

• Confirm the math with the width or BTU rule.
• Measure duct path and choose the right diameter from Table 2.
• Match hood width to the cooktop; add a small overhang when space allows.
• Plan makeup air for any hood at or above 400 CFM.
• Pick a multi-speed model with washable baffles and LED lights.
• Decide on blower location: in-hood, in-line, or remote.

The Bottom Line On Sizing Range Hood CFM

If you want a one-line takeaway, here it is: the width rule fits electric and induction on a wall, and the BTU rule fits gas. Start there, then tune for layout, duct, and cooking style.