KEVLAR®: Composites Grade vs. Ballistics Grade

Kevlar®: Composite grade vs Ballistic Grade


Not all Kevlar is created equal. What would be a great fit for building a kayak, might not be the greatest for protective vests or ballistic panels. So, what types are there? What are the most common types? (And more importantly, what is the best type for you?)

While there are several different grades, the two most common types are Kevlar 49, and Kevlar 29.

Kevlar 49 vs Kevlar 29

The most common type, Kevlar 49 fabrics are used in a variety of products; kayaks, canoes, high-speed boats, aircraft parts, and sporting equipment all make use of the Kevlar 49 fabric (just to name a few.) It is important to note that Kevlar 49 needs to be formed into a rigid, composite part in order to realize its full potential. That means that when working with Kevlar 49, you must pair it with a resin in order to complete your project.

Kevlar 29 meanwhile, are fabrics made of tough yarns that are built for ballistic protection. Typical applications include protective vests, gloves, hard armor helmets and ballistic panels. Unlike the Kevlar 49, this material is often used in its dry form without the aid of a resin to become a composite part.

When purchasing Kevlar for your project, make sure you choose the grade that is right for your needs. Kevlar can be a great alternative to carbon fiber and fiberglass, when increased impact and abrasion resistance is needed. Kevlar has great strengths which can fit the needs of a variety of demanding applications.

In order to make an informed decision, let’s take a look at the two Kevlar types.

Yarn Comparison

Unit Kevlar® 29 Kevlar® 49
Type denier
# of Filaments
Density lb/in³
Moisture Levels as Shipped* % 7 3.5
Equililbrium from Bone-Dry Yarn** % 4.5 3.5

*typical moisture levels on yarn shipped; they reflect values reached at normal, moderate temperature and humidity levels

following fiber production, which is a wet process.

**Equilibrium values are determined by bone drying the fiber and conditioning it at 75°F(24°C), 55% RH

Tensile Properties

Unit Kevlar® 29 Kevlar® 49
Breaking Strength lb
Breaking Tenacity g/d
Tensile Modulus g/d
10.2 x 10^6
Elongation at Break % 3.6 2.4
Resin Impregnated Strands*
Tensile Strength
Tensile Modulus psi

*Epoxy-impregnated strands, ASTM D2343

Thermal Properties

Unit Kevlar® 29 Kevlar® 49
In water at 212°F (100° C)
In dry air at 351°F (177°C)
Shrinkage Tension
In dry air at 351°F (177°C)
Specific Heat
At 77°F (25°C)
At 212°F(100°C)
At 356°F (180°C)
Cal/g x °C
Cal/g x °C
Cal/g x °C
Thermal Conductivity BTU x in./(hxft2 x °F)
[W/(m x K)]
ecomposition °F 800-900 800-900
Temperature in Air* (°C) (427-482) (427-482)
Recommended max temperature
range for long-term use in air
Heat of Combustion BTU/lb
(35 x 106)
(35 x 106)
Poisson’s Ratio 0.36

*Varies with rate of heating

Be sure to check out all of Fibre Glast’s Kevlar products. Looking for more information? Check out the DuPont Kevlar technical brochure.

Find what you were looking for? Let us know in the comments below. Be sure to follow us on Facebook and reach out to us on twitter at @Fibreglast for more news and information on the composite industries.

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1 s.c.mehta { 08.21.13 at 12:31 pm }

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5 prashant ankolekar { 03.02.15 at 1:53 pm }

actually i am a student and doing project on composite material. my matrix is epoxy and the reinforcement material i have selected is kevlar fabric. i want kevlar 49 but fiber glast is providing hybrid of carbon and kevlar, can i get pure kevlar 49 and is that hybrid fabric valid for this composite? plz help

6 { 05.12.15 at 12:45 pm }

We carry 3 options for woven Kevlar 49 Fabrics. Browse our selection at our website:

7 Kayaks Kevlar Vs. Fiberglass | Daily Great Tips { 07.16.16 at 8:57 pm }

[…] KEVLAR®: Composites Grade vs. Ballistics Grade – Fibre … – Kevlar ®: Composite grade vs Ballistic Grade . Not all Kevlar is created equal. What would be a great fit for building a kayak, might not be the greatest for … […]

8 GVR ENTERPRISES { 08.09.16 at 9:36 am }

we need kevlar 49

9 GVR ENTERPRISES { 08.09.16 at 9:37 am }


10 Joshua Leath { 09.20.16 at 2:50 pm }

You can find our current Kelvar 49 offering by clicking here.

11 jyoung { 08.17.16 at 1:59 pm }

That would depend on the type of fabric you are looking for. We currently have three options for woven Kevlar 49, you can view these on our website:

If you’d like, you can also email our sales team at

They’d be happy to give you a quote on whatever you need.

12 Lawrence { 10.01.16 at 6:22 am }

I recently made some kevlar-epoxy laminates and for some reason, the layers don’t bond well together. I am not sure whether the fabric I am using is 29 or 49. From this article, I presume what i have is kevlar 29. Kevlar 49 should have no problem with epoxy, or do I still need some surface treatment to improve adhesion?

13 tejaswi { 12.02.16 at 3:41 am }

why kevlar fbric is range like K29, K129 etc. what does it 29 and 129 indicated

14 Joshua Leath { 01.13.17 at 4:30 pm }

DuPont is continuing to improve those two basic materials, and assigning new numbers to the improvments. The basic pricinciple remains the same, but–for example–Kevlar 129 is a higher tenacity version of 29, and improved for ropes, cables, high pressure hoses, and ballistic applications.

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