Carbon Fiber- What is K?

Carbon Fiber- What is K?

Many buyers are scratching their head when they see in advertisement "3K" or "12K". What that means?

Lets have a closer look...
Carbon Fiber advertisement
Carbon Fiber advertisement

About K.

Have you heard about 3K and 12K topics with carbon fiber?  I think that you do. In case if you did not know then there are also 1K, 2K, 3K, 6K... 
To understand it we have to look deeper how carbon fiber plates are made.  
Carbon Fiber fabric
Carbon Fiber fabric


Carbon fiber is frequently supplied in the form of a continuous tow wound onto a reel. The tow is a bundle of thousands of continuous individual carbon filaments held together and protected by an organic coating.
Carbon Fiber tows
Carbon Fiber tows

Carbon Fiber tows.

First, let`s understand the main point. 12K means there are 12,000 filaments per "tow" and 3K means there are 3000. 
The tow can be conveniently unwound from the reel for use. Each carbon filament in the tow is a continuous cylinder with a diameter of 5–8 micrometers and consists almost exclusively of carbon.´s Carbon Fiber sheet´s Carbon Fiber sheet

1K Carbon Fiber

1K carbon fiber:  Is a very rare fiber.  It is lighter than other fibers and provides a more supple ride than a larger weave. 1k fiber is top of the bill, but the case is its expensive and low modules fibers more for finishing surface and most compagnys cannot even calc the stress inside a weave. 22,568 ft/lbs, 66 g/1000m´s Carbon Fiber sheet´s Carbon Fiber sheet

2K Carbon Fiber

* 2K carbon fiber: Is the rarest carbon fiber available on the market. It is produced by no more than 2 carbon manufacturers in the  world. This gives the plate perfect stiffness, low weight, and great vertical compliance (comfort). It is also very expensive.´s Carbon Fiber 3K sheet´s Carbon Fiber 3K sheet

3K Carbon Fiber

3K carbon fiber: The most popular, most common carbon fiber. It gives to the plate classic carbon fiber look. 3K is the workhorse of carbon fiber.  It's light, relatively stiff and easy to get and make. 3K got higher elongation before failure and ultimate strength than 6K, 9K or 12K. Because 3K is a smaller bundle of fibers, thinner fabric can be woven than with 12k, or thinner tubing can be filament wound, but if the fiber is the same grade, stiffness and strength are not affected by tow size. It is used in Aviation, industrial field, architecture, sporting, recreation goods. 7,523 ft/lbs, 198 g/1000m´s CNC cutted Carbon Fiber details´s CNC cutted Carbon Fiber details

6K Carbon Fiber

6K carbon fiber: It is easier to work with 6K & 9K than 12K. It wets out easier and it drapes better. It is used in Aerospace, building reinforcement, car tuning .7,523 ft/lbs, 396 g/1000m´s Carbon Fiber sheet´s Carbon Fiber sheet

12K Carbon Fiber

12K carbon fiber: Some factories might use a 12K to keep the cost down, because fabric is cheaper than the other K-s. 12K is easier to make hence you only need 1 layers in stead of 3 layers so less work too and cheaper.  Some say that they do not like 12K because its pattern looks big and robust. Generally the larger the weave, the stiffer it is, but is also heavier. It has higher tensile strength. It is not suitable for certain parts of the bicecycle.  It is used from military to industrial robotics to scientific equipment. A layer or two would probably be used in critical high-stress areas like the BB area, HT area and the chainstays. 1,862 ft/lbs, 800 g/1000m´s CNC cutted Carbon Fiber details´s CNC cutted Carbon Fiber details

24K & 48K Carbon Fiber

24K & 48K carbon fiber: It is used on manufacturing of filters, heat protection, sewing of working clothes, manufacturing of soft furniture and mattresses.
Unidirectional Carbon Fiber fabric
Unidirectional Carbon Fiber fabric

Unidirectional Carbon Fiber

Unidirectional carbon fiber: This carbon has fibers that run the same way rather than being woven together.  Is type of carbon fiber that can be used to create a carbon bicycles. . It is used also in  airplane wing spars where is needed strength and stiffness running along the length of the wing.