How Much Does My Foam Part Weigh?


When production is getting planned for a brand-new product, the shipping weight is usually needed before the part is complete. Not only does the part have weight, but the packaging does as well. The packaging may have not been produced yet, so it’s not as simple as throwing it on a scale.

Here’s how you can calculate the weight of your foam part – before it’s even fabricated.

Foam Weight Calculation

To calculate the weight of your foam, you need to use two metrics: calculate the volume of packaging in cubic feet, and then multiply the volume by density to get the weight. Put in one formula, it looks like this:

( Length x Weight x Height ÷ 1728 ) x Foam Density

The calculation will calculate the volume of the packaging in cubic feet. The parenthesis portion of the equation solves this. You can also use an online cubic feet calculator to make this process simpler. Next, multiply the volume by the density to get the weight.

When dealing with molded parts, taking the volume of material multiplied by the density will solve the weight of the part.

Example Calculation

Let’s walk through the process with a hypothetical: how much does a set of four foam end caps weigh?

a square foam piece, 12" wide, 4" depth, and 12" height

The graphic above shows a completed end cap

The end cap above has two pieces of foam laminated together to make one part. Below is how we solve for the volume:

a calculation showing (length x width x height / 1,7288) X Foam Density

Step 1:

(12 x 12 x 4)/1728 = .33 lbs per cubic foot

Step 2:

.33 x 1.7 = .56 lbs per part

Each part weighs .56 pounds! Well, not so fast…. There is a section of foam (8” x 8” x 2”) that is missing from one of the layers, and that needs to be subtracted from the .56 lbs per part.

Step 3:

(8 x 8 x 2)/1728 = .075 lbs of foam would fill that cavity

Step 4:

.56 - .075 = .485 lbs per part

Don’t forget to multiply the number of parts per package if there are more than one!

Step 5:

.485 x 4 = 1.94 lbs

With this calculation, we can say that our set of four endcaps collectively weighs 1.94 lbs (.485 lbs per part).

This is about as far as hand calculations can be taken before CAD models are needed. When using custom foam profiles or molded parts, the hand calculating is nearly an impossible feat.

Our experts at Foam Industries are standing by waiting to help if you need assistance.

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Foam Industries is a custom protective packaging company specializing in foam – with additional wood and plastic fabrication services. Our custom foam fabrication services are ideal for any type of packaging, display, or support service needed – from design to finished product.

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