How to Choose a Range Hood for Your Cooktop: Size, CFM and Noise

Key takeaways

• Match or slightly exceed your cooktop width: a 30‑inch hob generally pairs best with a 30‑inch hood (or wider if you cook a lot at high heat).
• For gas, a simple rule of thumb is 1 CFM per 100 BTU of burner output; for electric or induction, use kitchen volume (m³) × 10 as a starting point.
• Mount most wall and under‑cabinet hoods 65–75 cm above the cooking surface unless the manufacturer specifies differently.
• Noise is rated in sones or decibels; aim for around 1–3 sones (40–55 dB) on lower speeds for a comfortable kitchen, especially in open‑plan spaces.
• Even a compact visor hood such as the Cookology 60 cm visor cooker hood can be effective if its extraction and mounting height suit your space.

Why hood size matters

Hood size is about more than looks. The width and depth of the canopy determine how much of the steam, smoke and cooking odours are actually captured before they spread across your kitchen. A hood that is too small, or mounted too high, lets fumes escape around the edges, even if the fan is powerful on paper.

As a baseline, your hood should be at least as wide as your cooktop. So a 60 cm cooktop calls for a 60 cm hood. Many people choose to go slightly wider, especially over gas burners or when the hob is set into an island. A wider canopy gives a larger capture area, which is useful for front‑burner frying or when using large pans and griddles close to the edges.

Depth matters too. Under‑cabinet and visor hoods often sit shallower than wall‑mount chimney hoods. The deeper the hood, the better it can collect rising steam from the front burners. This is one reason why slim visor hoods tend to be practical in small kitchens, but they are best paired with moderate‑heat cooking or used on higher speeds when frying.

Standard cooktop widths are usually around 60 cm (30‑inch class) or 90 cm (36‑inch class). You will find hoods sold in matching sizes, but do not assume that all 60 cm hoods behave identically. Pay attention to both extraction rate and the canopy design when comparing similar‑width models.

What is CFM and how does it relate to BTU and room size?

CFM stands for cubic feet per minute and describes how much air a hood moves at its maximum setting. In the UK and Europe, product descriptions often list m³/h (cubic metres per hour) instead. The conversion is straightforward:

1 CFM ≈ 1.7 m³/h

So a hood rated at 217.6 m³/h, like the compact Cookology 60 cm visor cooker hood, moves roughly 128 CFM at full power. That is adequate for light to moderate cooking in a small kitchen, but would be under‑spec for a large gas range or very open‑plan space.

Using BTU to size a hood for gas cooktops

Gas burners are typically rated in BTU (British Thermal Units). A simple guideline is:

Recommended CFM ≈ Total BTU ÷ 100

If your cooktop has four burners totalling 40,000 BTU, you would look for a hood around 400 CFM (about 680 m³/h). This guideline assumes you cook regularly at medium to high heat and want robust fume capture when searing or stir‑frying.

If you mostly simmer and rarely use the highest settings, you may be comfortable with a slightly lower rating. Conversely, if you are a keen home cook who often uses multiple burners on high, choosing a model with a bit more capacity gives you a safety margin.

Using room size to size a hood for electric and induction

For electric and induction hobs, you can use a room‑volume method instead. Measure your kitchen in metres:

• Length × width × ceiling height = volume in m³
• Volume × 10 = recommended m³/h for around 10 air changes per hour

For example, a kitchen that is 3.5 m long, 3 m wide with 2.4 m ceilings has a volume of 25.2 m³. Multiply by 10 and you get a target around 250 m³/h (about 147 CFM). An extraction rate in that range is usually fine for everyday cooking on an induction hob, especially if you are not frying heavily.

In open‑plan layouts where the kitchen flows into a dining or living area, use the combined space that the cooking fumes can spread into, not just the area around the hob. That will often push the recommended airflow higher, and it is wise to favour stronger extraction in these setups to avoid lingering odours.

A simple rule: if you regularly see steam drifting across the room even with the hood on, you probably need either a higher‑CFM setting, a better‑sized hood or a ducted installation with less resistance.

Standard hood sizes and matching your cooktop

Most domestic hoods are grouped into a few common widths. Matching these to your cooktop is the first step before you drill into performance figures.

Example: 30‑inch (around 60 cm) cooktops

A 30‑inch cooktop is usually around 76 cm wide including trim, but the active cooking area tends to pair well with a 60 cm hood in compact UK kitchens. In a small, enclosed room with an electric or induction hob and moderate cooking habits, a hood in the 200–300 m³/h range can be perfectly adequate, as long as it is mounted at the correct height and the duct run is short.

If you have a 30‑inch gas cooktop with a total burner output in the 30,000–45,000 BTU range, you should be looking for something closer to 300–450 CFM (510–765 m³/h) if your layout allows it. In practice, many slim under‑cabinet and visor models will fall below this figure, so it is worth being realistic about how you cook and whether you are happy to open a window when you crank up the heat.

Example: 36‑inch (around 90 cm) cooktops

A 36‑inch cooktop benefits from a 90 cm hood to fully cover the outer burners. If you have a strong gas hob with, say, 60,000 BTU total, using the BTU rule gives you a target around 600 CFM (about 1,020 m³/h). That normally points you towards a more substantial wall‑mount chimney or a high‑capacity under‑cabinet hood with good ducting.

For a 90 cm induction cooktop in a medium‑sized kitchen, you can rely on the room‑volume method instead. A generous 4 m × 4 m × 2.4 m room has a volume of 38.4 m³, which would suggest roughly 380 m³/h. In practice, many people prefer a bit more headroom (for example, 450–600 m³/h) so the hood does not have to run on its noisiest setting too often.

Mounting heights and clearance

The vertical distance between the cooktop and the hood is crucial. Too low, and the hood feels cramped or even dangerous; too high, and extraction drops because fumes disperse before reaching the filters.

Most manufacturers specify a minimum and maximum mounting height, typically measured from the cooking surface to the bottom of the hood. Common guidance is:

• Gas cooktops: around 65–75 cm clearance
• Electric and induction: often 60–75 cm clearance

Always follow the instruction manual for your specific hood and hob. Gas flames add both heat and combustion products, so safe clearances matter both for performance and for fire safety. Some powerful gas ranges call for even greater distances or for a deeper, more enclosing canopy shape.

High ceilings can make mounting tricky. The hood still needs to sit at the right height above the cooktop, but you may have a long vertical chimney section above. Extensions are often available for wall‑mounted chimney hoods to bridge the gap, while island hoods usually come with adjustable hanging kits to keep the canopy at an appropriate working level.

Understanding noise: sones vs decibels

Range hood noise is often listed either in sones or decibels (dB). Both measure loudness, but in different ways. Sones are more common in North America, while decibels are used more widely as a general sound metric.

Very broadly:

• 1–2 sones ≈ quiet conversation or a modern refrigerator
• 3–4 sones ≈ normal conversation or light office noise
• 5+ sones ≈ raised voices or a loud extractor fan

For decibels, a typical hood might range from around 40 dB on the lowest speed to 65 dB or more on boost. Because decibels are logarithmic, a 10 dB increase sounds roughly twice as loud to the human ear. That means shaving just a few decibels off the top speed can make a noticeable difference to how comfortable your kitchen feels.

Practical noise targets for everyday use

If your kitchen is part of an open‑plan living area, it is worth prioritising lower noise. Look for a hood that offers a quiet low or medium speed in the region of 1–3 sones or around 40–55 dB. You can then reserve the highest, louder setting for intense frying or when something starts to smoke.

Compact visor and under‑cabinet models are convenient, but they sometimes need higher fan speeds to compensate for their modest extraction rates. Choosing a hood that matches your room size and cooking habits helps ensure you can run it at a mid‑range setting most of the time, keeping the noise footprint acceptable.

Ducted vs ductless: impact on CFM and noise

How your hood vents affects both real‑world extraction and sound levels. Ducted hoods expel air outside through a wall or roof. Ductless (recirculating) hoods filter the air and return it to the room. Each has pros and cons, and either approach can be workable when sized and installed well.

Ducted systems are generally more efficient at removing moisture and odours, especially if the duct run is short, straight and properly sized. However, poorly designed ducting with sharp bends or undersized pipe can add turbulence, reducing effective CFM and increasing noise. If you want to dig deeper into which style suits your home, it is worth reading a dedicated comparison of ducted vs ductless hoods.

Ductless hoods are easier to install because they do not need exterior venting. They rely on grease and carbon filters to capture particles and odours, so you will need to replace or regenerate those filters periodically. While they can be effective against smells, they do not remove humidity, which is important to bear in mind if you often boil large pots or steam food.

Whichever you choose, the quoted CFM or m³/h is typically measured at the hood outlet with no duct attached. Long or restrictive duct runs can reduce real‑world performance, so it is sensible to allow a margin above your calculated minimum CFM, particularly in complex installations.

Choosing a hood for gas vs induction cooktops

Gas and induction hobs behave differently, and that has knock‑on effects for the hood you choose. Gas produces combustion gases in addition to grease and steam, while induction heats the pan directly, often with slightly less apparent plume height.

For gas, pay close attention to the total BTU rating of your burners. If you have one large wok burner alongside several smaller ones, assume that you might run two or more high‑output zones at once when sizing your hood. That points you towards higher CFM and a canopy that fully covers the outer burners, particularly on 90 cm cooktops.

For induction, you can lean more on the room‑volume calculation. However, do not underestimate how much steam a large stockpot or pasta pot can generate. A hood that meets or modestly exceeds the volume‑based guideline gives you the flexibility to handle those occasional heavy‑steam sessions without filling the room with condensation.

Regardless of hob type, protecting the surface when the hob is not in use can increase its lifespan. Induction owners sometimes use a protective mat to guard against scratches when the hob doubles as extra worktop space. A magnetic silicone cover such as an extra‑large induction hob protector can help keep the glass surface clean and reduce minor knocks between cooking sessions.

Worked examples: putting the numbers together

Example 1: 30‑inch induction cooktop in a small enclosed kitchen

Imagine a 30‑inch induction cooktop in a 3 m × 2.5 m kitchen with a 2.4 m ceiling. The room volume is:

3 × 2.5 × 2.4 = 18 m³

Using the 10 air‑changes rule:

18 × 10 = 180 m³/h (around 106 CFM)

A visor or under‑cabinet hood in the 200–250 m³/h range, installed 60–70 cm above the cooktop, should be sufficient, particularly if you mostly simmer, sauté and bake. A compact design such as a 60 cm visor hood with around 200+ m³/h can suit this scenario, as long as you accept that very heavy frying might benefit from opening a window or using a higher fan speed for short bursts.

Example 2: 36‑inch gas cooktop in an open‑plan kitchen

Now consider a 36‑inch gas cooktop in an open‑plan area that combines kitchen, dining and living spaces. Suppose the combined area is 6 m × 4.5 m with a 2.4 m ceiling. The total volume is:

6 × 4.5 × 2.4 = 64.8 m³

Using 10 air changes per hour would suggest:

64.8 × 10 = 648 m³/h (about 381 CFM)

However, in an open‑plan setup, smells can drift quite easily, and if the gas cooktop has, for example, 55,000 BTU total, the BTU guideline gives you:

55,000 ÷ 100 = 550 CFM (about 935 m³/h)

Choosing a hood somewhere in the 600–900 m³/h range, with a 90 cm canopy and careful ducting, would give robust fume control for this kind of space. You would then expect to run the fan mainly on its medium setting, reserving maximum power for grilling, wok cooking or large‑scale meals.

Balancing power and noise with how you cook

The most powerful hood is not automatically the best choice if you never use its top settings because of noise. It is more realistic to select a hood where the mid‑range settings match your everyday cooking and noise tolerance.

If you cook mainly in the evenings and want to hold a conversation or listen to music without shouting, focus on the stated noise level at low and medium speeds. Having a boost mode as a backup is still useful, but living mainly in the quieter part of the range will make the hood feel more integrated into your routine.

Conversely, if you regularly fry, stir‑fry or griddle at high heat, a hood that can move more air gives you flexibility, even if that means a louder top setting. In this case, robust ducting and correct mounting height become just as important as raw CFM because they determine how effectively the hood can use its power.

Practical installation and usage tips

A well‑chosen hood still needs sensible installation and daily habits to perform at its best. Try to keep duct runs as straight and short as possible, using smooth‑walled pipe of the diameter specified by the manufacturer. Avoid excessive 90‑degree bends, which can create back‑pressure and reduce effective airflow.

Remember to switch the hood on a minute or two before you start cooking so that air is already moving when steam and smoke are produced. Leave it running for a few minutes after you finish to clear residual moisture and odours. Regularly cleaning the grease filters preserves airflow and reduces fire risk; metal filters can usually be washed, while carbon filters in recirculating systems need periodic replacement.

Finally, consider how you use your cooktop surface itself. If you often place items on the hob when it is off, an induction hob cover, such as a decorative vinyl induction hob protector mat, can reduce the chance of scratching the glass when using it as extra counter space.