Why Your Bathroom Mirror Fog Up? (And How To Prevent It!)

You’ve probably noticed how your bathroom mirror and other types of glass fog up when the air temperature is higher than the temperature of the glass.

While it’s perfectly normal, you may want to look at yourself after stepping out of the hot shower. Or perhaps it’s become frustrating to walk into your bathroom after somebody else has taken a bath and you’re unable to use the mirror properly.

Why exactly does this happen? Is there a way to keep it from happening? We discuss this and more in the following sections.

What Causes the Mirror to Fog Up?

The answer is one word: condensation.

When you take a hot shower, the air becomes saturated with moisture and water vapors. This increases the temperature of the air in the bathroom. 

Since the temperature of the mirror becomes significantly lower than the temperature of the air in the bathroom, the warm air condenses on the mirror’s surface and the mirror becomes fogged up. 

This is why whenever you take a shower you end up with a misty mirror and a cloudy image. The steam condenses on every cold object inside the room, but it’s most visible in your foggy mirror. 

How Do You Keep Bathroom Mirrors From Fogging Up?

No one likes to come out of a steamy shower to face a fogged-up mirror. If you try to wipe it away with your hands, it only pushes the water droplets to the sides and the image becomes only slightly clearer. 

Is there a way to prevent the mirror from fogging up?

You’ll be happy to know there is. Try the following:

Rub Soap on the Mirror

This is the easiest way to prevent the bathroom mirror from fogging up while you’re busy enjoying your shower. Before hopping into the shower area, take a bar of soap and rub it gently on the mirror. 

Cover the entire surface and don’t press too hard or you’ll be left with a distorted mirror image. The best way to do this is by taking a damp microfiber cloth and rubbing the soap on with it. Alternatively, you can also use Vaseline or liquid soap if you prefer.

Run Cold Water Before Hot

Don’t have time to layer soap on your mirror? Run the cold water before the hot water. When hot vapors come in contact with the surface of the cold mirror, fog happens as a result of condensation. 

If you run cold water for at least 30 to 40 seconds before a hot shower, the bathroom surfaces will remain cool and you’ll be able to prevent fog from forming for a little while.

Of course, this only works if you take short showers. If you have a small bathroom, your mirror will fog up faster compared to a larger one so you may want to lengthen the time you spend running cold water based on your bathroom size.

Shampoo Your Mirror

Place a small amount of shampoo on a paper towel and rub it across the entire surface of your mirror. When you’re done, you can rub off the excess shampoo from the surface with a clean paper towel.

Pro Tip: Wipe the mirror until it’s completely dry to avoid having a blurred reflection. You can also use shaving foam or toothpaste instead of shampoo.

Cool Your Bathroom

One of the easiest ways out of a fogged-up mirror is by cooling down the bathroom’s temperature. You can open a window where cooler air can enter to prevent the water vapors from forming on your mirror. 

Use a Vinegar Solution 

Combine water and vinegar using a 1:1 ratio. Spray the solution on the mirror and use a paper towel to wipe off the excess liquid. You can add a new coat to your mirror as necessary. It’s an inexpensive option and the vinegar solution will last you for weeks. 

You can also use the same solution to prevent your windshield and other glass surfaces from fogging up.

These solutions work because they create an additional layer on your mirror that water vapor doesn’t stick to.

How Do You Get Rid of Fog on a Mirror?

What if you already have fog on your mirror? Here’s how you can get rid of it:

  • Use a microfiber cloth dipped in vinegar to clean the surface of the mirror. 
  • Avoid using multi-purpose cleaners on the mirror. Instead, gently clean a fogged-up mirror with shaving foam
  • Dip a cotton pad in rubbing alcohol and wipe the fog off with it. 

When wiping your mirror, always use a soft cotton or microfiber cloth to keep it from scratching the surface. Avoid using abrasive materials like paper towels.

Why Does a Mirror Fog Up When You Breathe on It?

As kids, you may have played around with the mist that forms on glass surfaces. You may have used your breath to create a condensed area to draw or write on.

Here’s the science behind it: the air coming out of our mouths or nose is warm and full of water vapor. The higher the air temperature, the more water vapor it can hold. When the warm air from our mouths touches the cooler surface of the mirror, the air temperature cools and moisture condenses the air into droplets that form on the mirror’s surface. 

In a nutshell, the fog that forms on the mirror is the condensed moisture that comes from our breaths. 

Should You Keep the Bathroom Door Open or Closed After a Shower?(Important)

Our use of hot water encourages more water vapor inside the bathroom. If you want the mist in the bathroom and on your mirror to disappear as quickly as possible, keep the bathroom door open after showering. 

Keeping the bathroom door open after a bath will allow the water vapor to escape before it’s absorbed by the towels, curtains, cabinets, and other surfaces. If these vapors are kept inside the bathroom, you also encourage the growth of mold and mildew on the bathroom’s walls, ceiling, and other surfaces. 

The lower the temperature and humidity in your bathroom, the better. One of the easiest and best ways to keep them low is by keeping your bathroom door open, especially if you’ve just taken a shower.


Your bathroom mirror fogging up can seem like a minor thing but it can be irritating and prevent you from using your bathroom mirror the way it was meant to be used.

Now that you know the different ways you can prevent fog from building up, choose which one works for you best and enjoy a relaxing fog-free shower!