Mildew vs. Mold: How to Tell the Difference

If you see something that looks like mildew or mold growing on bread or a peach, you can just throw it out. That’s not an easy option, though, when you believe you see growth on a wall in your home. Trying to clean the area is a better idea. 

To make a plan for safe cleaning, it’s important to determine whether you’re seeing mildew or mold. Learn how to distinguish between mildew and mold so you can take the best steps to eradicate it.

What Are the Differences Between Mildew and Mold?

The primary difference between mildew and mold is that mildew has a dry, powdery texture with almost no thickness. Mold often looks slimy or fuzzy and has a slight three-dimensional look. Mildew is usually light-colored, while mold can be almost any color, including black.

Mildew vs. Mold: Differences in Appearance

Although mildew and mold both come from fungi, they grow and behave differently. Some of the signs of mold will differ from signs of mildew. 

Size

Mold typically has significant coverage on a damp space, while mildew may look more like small spots with patchy coverage. In other words, mildew won’t cover the space as thoroughly where it’s growing like mold will do.

Color

As a general rule, mold appears in darker colors than mildew. Green, brown, and black are common colors for mold, but it can appear in almost any color. Mildew is more likely to show up as light-colored spots of yellow, white, or gray. As mildew ages, it may turn brown. 

Odor

We wouldn’t recommend moving too close to the mold or mildew and taking a big sniff. Both mildew and mold smell awful, so you don’t want to get too close. Additionally, you’ll increase your risk of inhaling spores if you’re close. Instead, you can likely identify the odor from a few feet away. 

• What does mold smell like? Mold has a pungent, earthy odor that is highly unpleasant to most people.

• What does mildew smell like? Mildew has a musty or damp odor. It’s not quite as strong or distinctive as the odor of mold.

Texture

Mold's texture is significantly different from that of mildew. Mold has a fuzzy or slimy appearance with a noticeable thickness, while mildew is thin and powdery.

Where Found

Mildew prefers areas with high humidity and moisture, such as showers, bathroom drywall, or windowsills. Mold needs materials that are consistently damp, such as wood, carpeting, or drywall. Dark areas, like basements, are also prone to mold.

Mildew vs. Mold: Testing Differences

If you prefer to quickly test an area for mildew or mold yourself, a bleach test works well. Place a few drops of bleach on the growth. If it lightens in color immediately, you likely have mildew. Mold won’t noticeably change color under bleach. (Don’t use bleach on underlying materials that could suffer permanent color change or damage from the bleach.)

Although you can use bleach or buy testing kits for mold at a local hardware store, the best—and safest—option for how to test for mold or mildew involves hiring a professional. You have the risk of inhaling spores with a DIY test. A local mold testing professional can give you a definitive answer about what you have. 

Mildew vs. Mold: Health Risk Differences

For most people, exposure to mold or inhaling mold spores is more dangerous than exposure to mildew. Common mold-related health symptoms include difficulty breathing, congestion, and irritated eyes and skin. Mildew doesn’t cause dangerous health symptoms for most people. 

However, everyone reacts differently to these kinds of fungi. People who are significantly sensitive to mold or mildew may become quite ill. People with compromised immune systems or respiratory problems should avoid exposure to either mold or mildew.

Black mold is an especially toxic kind of mold that can make some people severely ill.

Mildew vs. Mold: Remediation Differences

Mold needs two to three weeks after the spores germinate to create a visible growth pattern. Mildew requires one to four weeks to become visible.

As mold grows, it penetrates the underlying material, ruining it and making remediation more difficult. Mildew stays on the surface of the material, simplifying cleaning.

To get rid of mildew, put on gloves, eye protection, and other protective gear. You can remove it with standard household cleansers. 

The Centers for Disease Control (CDC) says you can clean small mold coverage areas of less than 10 square feet yourself. However, you should reach out to a local mold removal professional if you have a large mold infestation or if you suspect toxic black mold. The average professional mold remediation cost ranges from $1,200 to $3,800 depending on the severity of the problem.

Mildew vs. Mold: Prevention Differences

The best way to prevent mold and mildew from returning—or from appearing in the first place—is to keep moisture away. Run fans and dehumidifiers in damp areas. If you have wet carpet or drywall from a flood or broken plumbing pipe, remove it as soon as possible.

After cleaning up any mold or mildew that’s growing, recheck the area every few days for signs of additional growth. Mold is far more difficult to eradicate completely, so preventing it from returning may require discarding damp materials (like drywall or carpet) and replacing them. Regular cleaning of the area is often enough to prevent mildew from returning.