Why is My Bathroom Fan So Loud?

My bathroom fan is super noisy.

Well, that’s super annoying.

Can I fix it?

The bad news is your noisy bathroom fan is probably super noisy for one simple reason that cannot be fixed. The good news is, if that one simple reason is not the reason it’s super noisy, it can be easy to fix.

All About the Noise

It’s good to know stuff, so let’s start with a little background information on noise. Noise is measured in “phons,” a unit of loudness level created by the American National Standards Institute. Appliance noise is rated by what’s called a “sone system”. Hang with us here, phon and sone are related. It’s actually a pretty easy, consumer-friendly system: 40-phons equal 1-sone. The smaller the sone number, the quieter the appliance. Your refrigerator, for example, is about 2-sones. Most bathroom ceiling fans rate 1.5 to 5-sones.

That means reducing the noise starts when you buy the bathroom fan. The smaller the sone number, the quieter the fan. Of course, if a bathroom fan is really quiet, it might not exhaust the air. You want a low sone number so the bathroom fan is quiet, but you want to make sure it’s going to move the air. After all, if it doesn’t, what’s the point of having a fan in the first place? Here’s where another term comes in: “CFM.”


A bathroom fan’s ability to move air is measured in Cubic Feet per Minute (CFM). The bigger your bathroom, the higher the CFM rating you’ll need. A fan should have a CFM rating high enough to replace the air in your bathroom at a rate of 8 times per hour. To figure out the CFM rating for your bathroom, use this formula: Length x Width x Height x 0.13 = Minimum CFM rating. The 0.13 is the number of recommended air exchanges per hour.

If you’re not a fan of math, the packaging should show the recommended square footage this fan can handle. Bathrooms 50 square feet and smaller typically have a CFM range of 50-79. For larger bathrooms, select a fan that can move at least 1 CFM per square foot of room. The fan for an 80 square foot bathroom should have an 80 CFM rating, for instance. In the end, you’ll want a good balance between a low sone number so it’s quiet and the correct CFM rating to make sure it moves the air.

Of course, chances are you’re talking about a  bathroom fan that’s already installed, but sone numbers and cubic feet per minute ratings are good things to keep in mind if you do have to buy a new fan.

Yep, this one is already installed and it’s super noisy.

This is the super easy fix for your bathroom fan. If it’s already installed and super noisy, your bathroom fan might need a little screw tightening. Turn off the power to the fan, remove the grill, grasp the fan and wiggle it. If it doesn’t move, you’re fine. If it does move, tighten the screws. Unfortunately, If the screws didn’t need tightening, chances are you have a cheap fan.

This is your one simple reason for super noisy fans that cannot be fixed. Dang it. Cheap fans usually have very fast motors with very small turbines. That means they move a lot of air, but they’re loud. Fans with a more powerful motor and a larger fan blade are the quietest fans. If you have a cheap fan, you’re going to have to live with the noise unless you replace it.

Wait, it wasn’t noisy until recently.

Well, that’s another story. And again, it could be easy to fix… or you probably can’t fix it. If your fan has been quiet and became noisy recently, the motor could be dirty. If there’s dust, dirt and crud in the fan, use a can of compressed air to blow it out. Then, clean up any debris with a hand vacuum. That’s pretty easy. Start the fan and see if the noise improves.

If the noise doesn’t improve, your fan motor may be dying and you can’t really fix it. Don’t worry, it’s fairly easy to just replace the motor and not the whole fan. While a new motor costs about the same as a new fan, at least you don’t have to tear out the old fan. If you buy a new fan, remember to get one that’s both quiet and moves air. You’ll pay more, but if you like a quiet fan, it’s better than having a fan that’s super noisy.

If you need help repairing or replacing a bathroom fan – or any other fan for that matter – keep EarlyBird Electric in mind. We’re available 24/7, so you don’t have to listen to that noisy fan for a moment longer!

The general knowledge and advice in this blog is designed to give you a little background information about your electrical system and may not be complete or contain minor errors.  Early Bird Electric is not responsible for any consequences if you attempt to fix your electrical problem using this information. It’s always a good idea to hire a local, licensed electrician like Early Bird Electric to safely and professionally handle the job.