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Follow along with ZOLTEK's progress as we make the news, attend events, and share our views surrounding commercializing carbon fiber

Carbon Fiber vs Fiberglass: What’s the Difference?

When it comes to carbon fiber vs fiberglass, can you tell the difference? Contrary to popular belief, the two are not one in the same. You’ll find that carbon fiber and fiberglass each have unique characteristics and provide unrivaled performance in specific applications. But to know which is right for your needs, you’ll want to know the differences between them (or trust that your fiberglass or carbon fiber manufacturer can steer you in the right direction, of course).

Key Differences Between Carbon Fiber and Fiberglass

Though carbon fiber and fiberglass share some similar attributes, and are used interchangeably in a handful of different industrial and everyday applications, the two materials are vastly different from one another. For instance…


Though either material is substantially stronger than steel, industrial carbon fiber is more than  20 percent stronger than the best fiberglass. Carbon fiber boasts a strength to weight ratio roughly twice that of fiberglass. For more on carbon fiber strength, check out our previous blog.


Carbon fiber is significantly less flexible than fiberglass and is the preferred material for applications in which stiffness and rigidity is essential (mechanical components for example).  Carbon fiber’ tensile modulus is 4 times that of fiberglass. For applications in which flexibility is required or rigidity isn’t imperative, fiberglass is often the preferred choice. 


Compared to metals like steel and aluminum, both carbon fiber and fiberglass materials are remarkably light in weight given their inherent strength. In environments and applications in which minimal weight is imperative (aerospace or car racing, for example) both materials are in high demand and used quite frequently. Typically, however, carbon fiber weighs about 15% less than fiberglass composites. 

Thermal Expansion

Unlike most materials, carbon fiber has a negative coefficient of thermal expansion which means that the material in its purest form actually expands in cold temperatures. However, the matrix in carbon fiber carries a positive coefficient of thermal expansion and the two typically offset one another for an overall coefficient of thermal expansion close to neutral. This is a fancy way of saying that carbon fiber materials do not contract in cold temperatures while fiberglass products may. So if extreme heat or cold is a factor, and thermal expansion is a concern, carbon fiber may be the better way to go.

Corrosion Resistance

If your carbon fiber or fiberglass application will be exposed to harmful chemicals, acids, or abrasive environments, you’ll be happy to learn that either material is highly resistant to corrosion or chemical abrasions. 


Generally, fiberglass components are viewed as more cost-effective as compared to their carbon fiber counterparts. This is due in large part to the fact that fiberglass is used in a wider range of applications and manufacturing costs are significantly lower. Carbon fiber manufacturing is a much more involved process and there are fewer established manufacturers in the industry.


Both fiberglass and carbon fiber boast excellent strength to weight ratios and are the superior and preferred material for a range of practical and industrial applications. However to say that they can or should be used interchangeably would be inaccurate. To learn more about carbon fiber and the benefits it offers, contact Zoltek.