Cooker Hood Buying Guide: How to Choose the Right Extractor

Most cooker hood advice starts and ends with looks, which is exactly backwards. A cooker hood is a ventilation appliance first and a design object second, and the two most common regrets, a hood that is too quiet to be any use or so loud you never switch it on, both come from ignoring the numbers. This guide walks through the figures that actually matter, so you buy a hood that clears the steam and grease over a real family dinner rather than one that just looks the part above the hob.

Start with extraction rate, not style

The single most important number on a cooker hood is its extraction rate, measured in cubic metres of air moved per hour (m³/h). Get this wrong and nothing else matters. The sensible way to size it is to work from the volume of your kitchen rather than guessing.

Measure length by width by height to get the room’s volume, then multiply by the number of air changes you want per hour. For a ducted hood that vents outside, aim for around ten air changes; for a recirculating hood that filters and returns the air, double it to twenty.

A worked example: a kitchen 5m by 4m with a 2.5m ceiling is 50m³. For a ducted hood, 50 × 10 gives a target of 500 m³/h. Add roughly 15 to 20 percent on top when you buy, because ducting bends rob you of airflow and you want the hood to do the job comfortably on a middle setting rather than screaming at full power. For open-plan kitchens or if you fry and roast most days, size up further.

Ducted versus recirculating

This is the choice that decides how well your hood actually works.

Ducted (extraction) hoods pull steam, grease and cooking smells out and vent them outside through ductwork. This is the more effective option by a distance, because it removes the moisture and odours entirely rather than just filtering them. It needs a route to an external wall or roof, so it suits kitchens where that run is short and practical.

Recirculating hoods pass the air through a grease filter and a charcoal (carbon) filter, then push the cleaned air back into the room. They take the smell out but not the heat or humidity, and they are less powerful, which is why you size them to twenty air changes rather than ten. They are the answer when ducting outside is impossible, for instance a flat or an island with no nearby wall. Keep in mind the running cost: charcoal filters are a consumable and need replacing every few months.

One planning point worth knowing: under the current Building Regulations (Part F), a recirculating hood on its own is not enough to meet the ventilation requirement in a new-build kitchen, so a separate extract fan to outside is also needed. Existing kitchens being refitted are more flexible, but it is worth checking with your installer. The Building Regulations Part F guidance is the authoritative source.

Match the width to your hob, then go wider

As a rule, your hood should be at least as wide as your hob, and ideally a little wider so it captures the plumes rising from the front burners. A 60cm hob wants a 60cm hood as a minimum; a 90cm hob or range cooker wants a 90cm hood at least. If you have the space above a range, stepping up to a wider hood improves capture noticeably, which matters most if you cook on a big 90cm range cooker or larger. See our range cooker buying guide for how hob width and hood width should be planned together.

Mounting height matters too. Most manufacturers specify a gap of around 65 to 75cm above a gas hob and slightly less above induction; too high and the hood loses efficiency, too low and you risk heat damage and banging your head over the pan.

Noise: the spec people forget

A powerful hood you never turn on because it drowns out conversation is money wasted. Noise is quoted in decibels (dB), and the figure usually refers to the maximum speed. Many hoods hit 70dB or more flat out, which is genuinely loud. Aim for a hood that sits around 55 to 60dB on its normal setting, roughly the level of a conversation, and treat the boost speed as a short burst for when a pan boils over rather than something you run all evening. A hood that is oversized for the room can run on a lower, quieter setting and still shift the air, which is another reason to size generously.

Hood types and the practical trade-offs

• Chimney hoods are the classic wall-mounted stainless or glass hoods above a hob or range. Effective and easy to find in 60cm and 90cm widths.
• Integrated and canopy hoods hide inside or under a cabinet for a seamless look, drawn out or switched on when you cook. Neat, but often less powerful.
• Island hoods hang from the ceiling over an island hob. They need to work harder because there are no walls to help contain the plume, so size up the extraction rate and check the noise figure carefully.
• Downdraft extractors rise up behind the hob. They keep sightlines clear but tend to be pricier and less powerful than an overhead hood of the same money.

Filters, lighting and the small stuff

Every hood has a metal grease filter that you should be able to remove and put through the dishwasher; check this is dishwasher-safe before you buy. Recirculating models add charcoal filters that need replacing periodically, so factor that into running costs. LED lighting is now standard and worth having, since decent task lighting over the hob is genuinely useful. Finally, look at how easy the controls are to reach and clean, and whether the ducting outlet is on the top or the back, because that decides how your installer routes the duct.

For the wider kitchen picture, our guide to kitchen cabinet sizes helps you plan the run of units the hood sits within.

Frequently asked questions

What extraction rate cooker hood do I need? Multiply your kitchen’s length, width and height to get its volume in cubic metres, then multiply by ten for a ducted hood or twenty for a recirculating one. A 50m³ kitchen needs about 500 m³/h ducted. Add 15 to 20 percent on top to allow for ducting losses and comfortable mid-speed running.

Is a ducted or recirculating cooker hood better? Ducted is more effective because it vents steam, grease and smells outside rather than filtering and returning the air. Choose recirculating only when ducting outside is impractical, and remember it removes odours but not heat or humidity, needs charcoal filters replaced regularly, and must be sized to a higher airflow.

What size cooker hood do I need for a 90cm hob? At least 90cm, matching the hob width, and wider still if space allows so the hood captures the plumes from the front burners. Under-sizing the hood is one of the most common reasons a kitchen stays steamy despite the extractor running.

How loud is a cooker hood and what is acceptable? Many hoods reach 70dB or more at full power. Aim for one that runs around 55 to 60dB on its normal setting, similar to a conversation, and use the boost speed only in short bursts. An oversized hood can move the same air more quietly on a lower setting.

Do cooker hoods have to vent outside by law? In new-build kitchens under Building Regulations Part F, a recirculating hood alone does not meet the ventilation requirement, so a separate extract fan to outside is needed. Existing kitchens being refitted have more flexibility, but a ducted hood is always the more effective choice, so check with your installer.

How often should I clean or replace cooker hood filters? Wash the metal grease filter every few weeks, or more often with heavy cooking; most are dishwasher-safe. On recirculating hoods, replace the charcoal filters roughly every three to six months, since a clogged carbon filter stops removing odours and restricts airflow.