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What Are Bathroom Fans for? Find Out if You Need One

Nearly every modern bathroom is equipped with a ventilation fan. While you may already turn this fan on before taking a shower, you may not know why it’s so important to do so. And, if your home lacks bathroom exhaust fans, you may be wondering how badly you need one.

Bathroom fans are primarily used to reduce moisture in the air and on surfaces, but they also help to keep bathrooms odor-free and safe from carbon monoxide build-up. Bathrooms can function without a bathroom fan, but having one can help prevent costly mold problems.

This article will explain what bathroom fans are, what they’re used for, and why every bathroom can benefit from having one. We’ll also discuss what features to look for when choosing a new bathroom exhaust fan.

What Are Bathroom Fans?

Most bathroom fans are bathroom exhaust fans, also known as bathroom ventilation fans. They differ in many ways and are often categorized based on their mounting placement. For example, you can find bathroom fans that mount to the:

  • Ceiling
  • Wall 
  • Window
Bathroom fan on a ceiling, wall and window illustration

The best place to mount a bathroom fan depends on the homeowner’s preferences and needs, as well as their budget. Each mounting type has specific advantages and disadvantages, so it’s important to be familiar with each one before browsing for a new bathroom fan.

Ceiling Mount

Ceiling-mounted bathroom ventilation fans are fantastically popular. They tend to ‘tuck away’ into the ceiling, leaving only a light or grill surface exposed. The fan then connects and secures to a duct that leads to the roof or outside of the building.

Ceiling mount bathroom exhaust fans can vary greatly in size. Some of the smaller models may only be about 8in (20cm) long, while the higher-capacity fans can top-out at just above 20in (51cm) in length. In most instances, the larger bathroom fans are capable of eliminating moisture from larger areas. 

Homewerks 7117-01-BN Bathroom Integrated LED Light Ceiling Mount Exhaust Ventilation 1.1 Sones 80 CFM, Bath Fan Brushed Nickel

Still, there are some exceptions to this rule. A standard-sized 10in x 10in bathroom exhaust fan can ventilate over 100 cubic feet per minute (CFM), which is comparable to many larger models. Ceiling mount bathroom fans may also feature large lamps or lights that are both stylish and functional.

Owners of these types of bathroom fans must be sure to clean them at least once a year, preferably more frequently. Here is a guide on how to clean a bathroom fan.

Because they are typically inlaid into the ceiling, this cleaning process might be a little tricky. Always have someone with you when using a ladder to reach the bathroom fan cover.

Of course, if you’d rather have easier access to your bathroom fan’s internal mechanisms, you can always decide to invest in a wall-mounted fan. 

Wall Mount

Wall-mounted bathroom fans are a fantastic way to ventilate first-floor bathrooms or windowless bathrooms. They can also offer easier cleaning access, leading to fewer fan-fueled fires. However, a window mount bathroom fan can become a hazard when furniture, cloth, or other obstructions block the cover.

Broan-Nutone 509S Through-the-Wall Ventilation Fan, White Square Exhaust Fan, 8.5 Sones, 200 CFM, 8"

If you are planning on installing the fan on the wall read my article about installing a bathroom fan vertically.

Fortunately, most ceiling mount fans are also compatible with walls. This means that homeowners can choose a compact, high-powered bathroom exhaust fan that doesn’t take up excess wall space.

Still, a window mount fan is certainly worth considering if you’re hoping to avoid in-depth installations and drywall repair. 

Window Mount

When a ceiling-mounted or wall-mounted option just isn’t viable, a window-mounted fan may be the best choice. While these bathroom fans tend to be a bit bulkier and potentially louder than their wall/ceiling counterparts, they can be just as effective at eliminating moisture and reducing foul odors. 

Comfort Zone CZ319WT 9-inch Twin Window Fan with Manual Reversible Airflow Control, Auto-Locking Expanders and 2-Speed Fan Switch

Window mounts can become clogged with leaves or make it easier for insects to enter a home. Some models may also become electrical hazards during inclement weather, such as a strong thunderstorm.

However, one of the benefits of using a window mount bathroom fan is affordability. These types of exhaust fans don’t require invasive installation, making them ideal for rented living spaces and individuals on a tight budget.

What Are Bathroom Fans Used for?

Bathroom fans are used in three primary ways. They can:

When used correctly, bathroom fans pose very little danger to homes or their inhabitants.

Because they can help prevent hazardous molds and mildews from taking over a bathroom, exhaust fans can save a homeowner hundreds of dollars in mold remediation and repair, not to mention potential healthcare costs. 

Bathroom fans can also help remove poisonous gases from home, helping to lessen the chance of toxic exposure to carbon monoxide leaks. And those who enjoy a fresh-smelling powder room are sure to enjoy the odor-lessening effects of these air-clearing devices.

Here are 8 alternative ways to keep your bathroom smelling fresh!

Still, the ultimate objective of any bathroom ventilation fan is to keep spaces dry and mold-free. Wet showers, tub surfaces, or bathroom floors can quickly become expensive household dangers.

Eliminating Moisture

Bathroom exhaust fans can remove and help eliminate bathroom moisture by pulling humid air out the room and out of the home via a vent or series of fans. Unlike heaters or fans that blow air into a room, bathroom fans help keep things dry by removing air.

Keeping Homes Safe

Carbon monoxide poisoning affects thousands of Americans each year. Anyone with a home furnace or gas-powered appliance can fall victim to this type of danger. While it’s important to invest in carbon monoxide detectors (and periodically check to ensure that those detectors are properly functioning), a bathroom fan may also help save lives in the event of stray gas.

How bathroom exhaust fan works illustration.jpg

That’s because bathroom exhaust fans don’t re-circulate air. They instead pull air out of a room, making them a fantastic emergency method of reducing carbon monoxide levels in a home. Of course, no bathroom fan should ever run for hours-on-end. Still, these hands ventilation machines could mean the difference between life and death in a gas-related crisis.

Removing Foul Odors

Speaking of gas-related crises, bathrooms tend to smell a little funky from time to time. This is partially due to the presence of mold or mildew, but regular usage can result in pockets of methane lingering in your restroom.

Methane gas can be just as dangerous as carbon monoxide, but only when mixed with other gases. The gas causing your bathroom to stink likely isn’t lethal. Still, a great-smelling bathroom can help you to relax and enjoy your bath, shower, or toilet time. 

Foul odors can be embarrassing, and stale scents could be a sign of mold growth. Bathroom fans can help pull gas and mold spore up and out of the room, resulting in a space with a more neutral smell.

Do You Need a Bathroom Fan?

All bathrooms can benefit from having an outdoor fan. Unless your bathroom is already equipped with several significant forms of ventilation (such as a copious amount of open windows or an absence of walls), you will need to install a bathroom fan to keep the space mold-free, mildew-free, and smelling fantastic. In fact, a bathroom fan is required by law in most cases.

Of course, if you decide to go without a bathroom exhaust fan, there are a few situations you can look forward to experiencing. The first of these is rampant mold growth and its consequences.

Find out how does a bathroom exhaust fan work

The Dangers of Excess Moisture

While moisture doesn’t seem like a bad thing, especially in the bathroom, it can become dangerous. That’s because moisture attracts mold and mildew growth, as well as certain types of pests and insects. The most significant moisture-related dangers bathrooms face include:

  • Toxic mold growth
  • Damaging mildew spread
  • Increased allergens and irritants
  • Slip hazards

Mold only grows in places where it has plenty of access to food and water. Molds can consume almost anything, from wood to plastic. And water can be found in nearly every part of the world, especially in rainy or humid climates. This means that mold can be difficult to avoid.

Underfloor heating in the bathroom will also help keep the moisture levels down.

20 Sqft Electric Floor Heating System with Required GFCI Programmable Thermostat 120V

Proper ventilation can help reduce the amount of mold growth because it lessens the amount of moisture in an enclosed space. Because mold spores have less access to water, they’re less likely to take hold and flourish. When proper bathroom fan ventilation is combined with regular cleaning, homeowners can also prevent mildew build-up.

When mold and mildew are taken out of the equation, household allergens are significantly reduced, and residents can breathe more easily. With fewer sinus infections and upper respiratory illnesses to contend with throughout the year, you may even be able to save a little money on healthcare expenses while enjoying improved overall health.

What Should You Look for in a Bathroom Fan?

After committing to bathroom fan installation, it’s important to choose the right exhaust fan for your space. To do this, you’ll need to consider a few crucial factors, such as:

  • CFM capability
  • Fan type
  • Noise
  • Lighting

There are also a few additional features to think about, like automatic shut-off mechanisms or space-saving design. As long as you meet the space needs of your bathroom and are happy with the amount of noise the fan makes, you’re good to go. Of course, it’s also vital to stay within your budget.


Room Size

The size of your bathroom will help you to determine which bathroom exhaust fan is right for your space. Each type of fan comes in various sizes, and some are capable of ventilating very large bathrooms while others can only handle small spaces.

When browsing through bathroom fans, always remember to choose one that meets the needs of your room’s size. The best way to determine how powerful a fan you’ll need is to first calculate your bathroom’s square footage. Having a measuring tape handy will help you immensely. 

Once you’ve arrived at a number, you can begin searching for the right-sized bathroom ventilation fan. You’ll want to choose a fan that can move every cubic foot of space of air per minute.

For example, if your bathroom is 60 ft², you’ll want to invest in a fan that is rated to at least 60 CFM. 

Of course, where you’ll be installing your fan is just as important as your new fan’s ventilation capabilities. That’s why it’s crucial to also consider what type of bathroom fan you’d like to have.

Fan Type

As mentioned above, there are three popular types of bathroom fans. These include ceiling-mounted fans, wall-mounted fans, and window-mounted fans. The best type of fan for your bathroom and home depends on several factors.

While ceiling-mounted fans tend to be the most popular type of bathroom fan, they may be impossible to install in rooms that are distant from exterior walls or roof-access vents. In those cases, a window mount fan or wall mount fan may be a better option.


Of course, wall-mounted and ceiling-mounted fans tend to require at least a little drywall or ceiling work, which may not appeal to every homeowner. Those looking for the fastest and least invasive bathroom fan option may want to consider a window-mounted model. 

Still, if your bathroom only has a small privacy window or is completely windowless, your best bet may be a fan that requires a little extra time, patience, and installation know-how. If you’re not familiar with bathroom fan installation, it may pay to hire a professional to help you. 

After all, a properly installed bathroom fan is bound to function safely, enjoy a longer lifespan, and generate less noise.


Most bathroom exhaust fans fall into one of three different noise levels. These levels are measured in sound pressure waves known as sones. The three most common sone zones for bathroom fans are:

  • Under 1.5 Sones
  • 1.5 to 3 Sones
  • Above 3 Sones

You can find a Sone to Decibel calculator here

To put these measurements into perspective, you can think of 1.5 sones as just about the loudness of a whisper. On the opposite end of the bathroom fan noise spectrum, there are three sones, which is the typical volume of a friendly conversation. Any device that produces a sone rating between these two points is comparable to a gentle stream or fountain.

A great way to significantly reduce the noise level is to slow down the fan.

Read my article about how to slow down a bathroom fan if you wish to learn more.


If you’re looking to install a little more lighting in your bathroom and you’re in need of a bathroom exhaust fan, you may want to consider investing in a fan that is equipped with some type of lamp. 

Homewerks 7146-80-MS Bathroom Fan Integrated Dimmable LED Light Humidity Sensor Exhaust Ventilation 1.5 Sones 80 CFM, Smart Motion White

Some fans also have dim night lights that can help residents see more clearly without having to turn any lights on. You can select a model that has just the right amount of light intensity for your needs.

Additional Features

There are quite a few attractive features to keep an eye out for when considering a new bathroom exhaust fan. Some of the most common additional features include:

  • Humidity sensors
  • Motion sensors
  • Energy-saving night lights
  • Heaters
  • Bluetooth speakers

Woman in a robe while a music is coming from a bathroom fan, modern bathroom with white walls.jpg

Depending on your preferences, some of these features may be more desirable than others. For example, if you typically forget to turn your bathroom fan on and off (or you’re simply not accustomed to having one), it may be a good idea to get one that has humidity or motion sensors. 

If you live in a frigid area that is prone to frozen pipes and ice-cold waters, you may want to consider getting a bathroom fan that is equipped with a heater. While the fan won’t blow warm air downwards, it can help add a little heat and comfort to a stone-cold winter bathroom.

You could even invest in a bathroom ventilation fan that has Bluetooth capabilities. That way, you can blast your favorite tunes while taking excellent care of your bathroom and your hygiene. This feature might be worth the extra expenditure if you’re a shower singer. 


Bathroom fans are often used to ventilate a home’s bathrooms. This type of airflow helps to minimize moisture, remove bad smells, and keep homes free of dangerous gases and airborne chemicals. 

There are three main types of bathroom exhaust fans, and they each have design-specific advantages and disadvantages. While any bathroom can benefit from an exhaust fan, the choice to add one is completely up to you. 

However, it’s important to consider how costly mold and mildew damage can be. The immediate investment of purchasing and installing a bathroom fan is typically far less than the cost to repair mold damage. 

To enjoy the healthiest, cleanest, and freshest-smelling bathroom possible, be sure to acquire a bathroom ventilation fan that is appropriately sized for your room, fits your budget, and that doesn’t make too much noise. 

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