Materials Calculator for Carbon Fiber, Fiberglass, Resin and more.

Whether you're working with fiberglass, carbon fiber, or Kevlar, this calculator helps you determine how much material and resin you'll need based on the size and number of your parts. No more guesswork — just quick, accurate estimates that help you buy exactly what you need.

It’s perfect for both beginners and seasoned professionals looking to save time and money on material planning.

The Materials Calculator can be found here.

INPUTS

Step 1 - Enter Dimensions and Desired Thickness

Start by inputting the basic measurements for your composite project:

Length and Width – Enter the size of the part or mold you plan to fabricate.

Desired Thickness – This determines how many layers of reinforcement you'll need.

Tip: If you're not sure how thick your part should be, see below for help choosing layers and materials.

Step 2 - Select Materials for Your Project

Next, choose the reinforcement material you'd like to use from the drop-down menu, such as:

• Chopped Strand Mat
• Woven Fiberglass
• Carbon Fiber
• Kevlar®

Not sure what to use?
Consult our white paper: What Do I Need for My Composite Project?

Adjusting Layers for Thickness

If you know your desired thickness (e.g., 0.25"), you can increase the number of fabric layers to reach it. For example:

Using 6 layers of Chopped Strand Mat will help achieve a thickness slightly over 0.25” which is ideal for mold building.

Alternatively, if you already know the number of layers you want to use, the calculator will reverse-calculate the final part thickness.

 Note: Be sure to account for core material and coating thickness:

• Gel Coat / Surface Coat: Add ~0.020"–0.025"
• Core material: and 0.125”-2” depending on thickness you choose
• Paint / Clear Coat: Typically, negligible in thickness: 0.001-0.003” 
  

RESULTS

On the right side of the calculator, you’ll find a summary showing:

• Estimated Final Thickness (excluding core and coatings)
• Total Fabric Required
  

Fibre Glast sells fabrics in:

• Pre-packaged sizes: 1, 3, and 5 yards
• Cut-to-length: Starting at 10 yards

Round up your order to ensure you have enough material, especially for odd shapes or layered builds.
 
Estimate Resin Requirements

The calculator also estimates how much resin you’ll need, based on:

Formula: Resin weight = Fabric weight × 1.75
This result is shown in pounds, matching how resins are sold at Fibre Glast. Be sure to check the product description for weight per unit:

• Example: A gallon of 78-A Polyester Resin weighs ~9 lbs.

In Practice:
If your project requires 6.429 lbs. of resin:

• 1 gallon (9 lbs.) covers it with margin
• If you’re skilled at hand lay-up and want less waste, 3 quarts (~6 lbs.) may suffice
  

Print the results for future reference.

Final Thoughts

The Fibre Glast Materials Calculator is designed to make your project planning smarter and more efficient. With just a few inputs, you’ll know:

• How much fabric to order.
• What your final part thickness will be.
• How much resin is needed down to the pound.

Head over to the calculator and plan your next lay-up with confidence: Try it now!