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The first range hood I ever pulled apart on a service call looked spotless from the front. Behind the grille it was a different story. A recirculating unit over a gas cooktop, three years of frying, and the charcoal filter had turned into a solid greasy brick that had stopped absorbing anything a long time ago. The kitchen smelled like last night’s dinner because that air had nowhere to go but back into the room.
That job is the whole comparison in a nutshell. A range hood either sends kitchen air outside or it recycles it. The choice between range hood vented vs recirculating decides how much grease, moisture, and odor actually leaves your kitchen versus how much just gets pushed around.
What each type actually does
A ducted hood pulls air up through a grease filter, then pushes it through a duct and out a wall or roof cap. Grease, steam, cooking odors, and a good chunk of the heat all leave the building. Fresh air replaces it from elsewhere in the house.
A recirculating hood does the first part, then stops. Air passes through a metal grease filter and a charcoal (activated carbon) filter, and then blows back out the top or front of the hood into the same kitchen. No duct, no hole in the wall.
The charcoal filter is the entire argument for recirculating, and it is also its biggest weakness. It only adsorbs so much before it is full.
That distinction matters most for the three things a hood is supposed to handle: grease, moisture, and odor. Let me take them one at a time.
Grease, moisture, and odor removal compared
Grease
Both types catch the heavy grease at the metal baffle or mesh filter, so your cabinets and walls stay cleaner either way. The difference is the fine aerosol that slips past. A ducted hood carries that outside. A recirculating hood relies on the charcoal filter to grab some of it, and a fair amount still settles back onto nearby surfaces over time.
Moisture
This is where recirculating simply cannot compete. Charcoal filters do nothing for water vapor. Boil a big pot of pasta or run a steamy stir-fry under a recirculating hood and that moisture goes right back into your kitchen air, fogging windows and feeding humidity. A ducted hood is the only version that removes steam, which is a real factor if you already fight condensation.
In a tight, well-sealed home, a recirculating hood does nothing to lower kitchen humidity during cooking. If your windows sweat when you cook, ducting outside is the fix, not a bigger charcoal filter.
Odor
Fresh charcoal handles light odors decently for a while. It fades. By month four or five, a saturated carbon filter is barely working, and fish or bacon smell lingers the way it did in that service-call kitchen. Ducted hoods sidestep the whole problem by exhausting the odor outdoors.
| Factor | Ducted (vented outside) | Recirculating (charcoal) |
|---|---|---|
| Grease aerosol removal | High, sent outdoors | Partial, some resettles |
| Moisture and steam | Removed from kitchen | Not removed at all |
| Odor control | Strong and consistent | Good when filter is fresh, fades |
| Heat removal | Yes, cools the kitchen | No, returns heat to room |
| Install effort | Higher, needs a duct run | Low, plug and hang |
| Ongoing cost | Clean or swap grease filter | Charcoal filter, $15 to $40 every 3 to 6 months |
Cost and installation reality
The hood itself often costs about the same in either mode; plenty of models ship convertible, meaning you can duct them or add a charcoal kit. The money and the effort live in the ductwork.
A straightforward ducted install with a short run to an exterior wall might run $200 to $600 in labor if you hire it out, more if you are cutting through brick, running up through a roof, or fishing duct through finished ceilings. Recirculating skips all of that, which is its genuine appeal.
Size a ducted hood for roughly 100 CFM per linear foot of cooktop. A 30-inch range wants around 250 to 300 CFM; a serious gas range or wok setup wants more. Undersized airflow is the most common reason a good hood underperforms.
If you do duct it, the duct matters as much as the fan. Use smooth-wall rigid metal, keep the run short and straight, and minimize elbows. Flexible foil duct and long twisty paths choke airflow and trap grease, which is a fire risk over a cooktop. The U.S. Department of Energy has solid background on home ventilation and airflow at Energy Saver, and the EPA’s indoor air quality pages explain why exhausting cooking pollutants outdoors matters for gas cooktops in particular.
Which one to pick for your kitchen
The honest answer depends on how you cook and what you can build.
Pick ducted (vented outside) if: you cook with real heat, fry or sear often, run a gas cooktop, deal with kitchen humidity, or can reasonably reach an exterior wall or roof. It is the better performer on every metric that matters, full stop.
Recirculating is a reasonable fallback when: you physically cannot run a duct. That is common with an island cooktop on an interior slab, a mid-rise condo where you cannot pierce the building envelope, or a rental where cutting the wall is off the table. If you cook lightly, mostly boiling and reheating, and you commit to changing the charcoal filter on schedule, it will keep the worst of the odor down.
- Confirm whether an exterior wall or roof route exists before you buy.
- Check your CFM against your cooktop width and fuel type.
- If recirculating, buy two charcoal filters up front so you never skip a change.
- For ducted, plan for smooth rigid metal duct and a proper exterior cap with a backdraft damper.
- Make sure a strong ducted hood is not starving a gas water heater or furnace of air (backdrafting).
Many hoods are convertible. If you buy recirculating now because you cannot duct yet, pick a model that can be converted to ducted later so a future remodel does not mean a new hood.
One caution people forget: a high-power ducted hood is a big exhaust fan. In a tight house it can pull combustion gases back down a flue if there is no makeup air. If you are also weighing whole-home options like exhaust only vs supply only ventilation, or sizing a bathroom exhaust fan by CFM elsewhere in the house, the same airflow-balance thinking applies here.
The short version before you buy
If you can get a duct to the outside, do it. A ducted hood is the only one that removes steam, heat, and the odors you actually notice, and it keeps grease from resettling around your kitchen. Recirculating earns its place only when ducting is truly impossible, and even then it is a compromise you maintain with fresh charcoal every few months.
Walk to your cooktop, look at the nearest outside wall, and be honest about how you cook. That five-minute reality check will tell you which hood belongs in your kitchen better than any spec sheet.
Frequently asked questions
Is a recirculating range hood better than nothing?
Yes, but only a little. A recirculating hood catches heavy grease at the metal filter and knocks down light odors while the charcoal filter is fresh. It does nothing for steam or heat and lets fine grease resettle in the kitchen. If you cannot duct outside, it beats no hood, as long as you replace the charcoal filter on schedule.
How often do I replace the charcoal filter in a recirculating hood?
Plan on every 3 to 6 months with regular cooking, sooner if you fry or cook heavily. Charcoal filters run about $15 to $40. Once saturated they stop adsorbing odor and just add airflow resistance, so a stretched-out filter is why many recirculating hoods seem to quit working after a year.
Can I convert a recirculating hood to vent outside later?
Often yes. Many hoods ship convertible, meaning the same unit can duct outdoors or run recirculating with a charcoal kit. Check the model before buying if you think a remodel might add a duct route later. Converting usually means removing the charcoal filter, opening the correct knockout, and connecting rigid metal duct to the outside.
Does a range hood need to vent outside for a gas stove?
It is strongly recommended. Gas cooking produces moisture and combustion byproducts you want out of the house, and a ducted hood is the only type that removes them. The EPA highlights venting gas cooktops outdoors for indoor air quality. Recirculating does not clear those gases, so ducted is the safer choice over gas.
What size CFM do I need for a vented range hood?
A common target is about 100 CFM per linear foot of cooktop width. A 30-inch electric range is fine around 250 to 300 CFM. Powerful gas ranges and wok burners want more. Keep the duct short, straight, and smooth-walled, because a long or kinked run cuts real airflow well below the fan's rating.
Will a strong ducted hood cause any problems in a tight house?
It can. A high-CFM hood pulls a lot of air out, and in a well-sealed home that can backdraft a gas furnace or water heater, drawing combustion gases inside. If you install a powerful ducted hood, ask about makeup air so the house can replace what the hood exhausts. This is not a concern with recirculating units.
Dharm Solanki
Dharm Solanki spends a lot of time thinking about the air inside people's homes, usually when no one else is. He writes about humidity, ventilation, and dehumidifiers, along with the small fixes that turn a stuffy or damp room into one that feels comfortable again. He would rather explain why a recommendation works than just point at a product, so his guides tend to answer the question you were about to ask next. And if something looks great on paper but struggles in a normal house, he says so.
