# Trailer Weight vs. Volume : Dump Trailers

A common misconception among dump trailer users, as well as many dump trailer dealers, seems to be that the amount of material a trailer is capable of hauling is directly related to the size of the box. This is completely false.

We would like to offer a few examples to hopefully help dealers educate their customers.

These examples are based on the following facts:

- 27 cubic feet = 1 cubic yard.
- Payload is calculated GVWR minus weight of trailer.
- Dry fill dirt weighs approximately 2000# per cubic yard
- Dry ¾” gravel weighs approximately 2200# per cubic yard
- Dry mixed sand weighs approximately 2400# per cubic yard

For these examples we will use dry ¾” gravel. We'll "fill" each trailer and illustrate how quickly a dump trailer can be overloaded.

**Example 1**

A 5x10 single axle dump with 5200# axle and 24” sides has an estimated payload of 3250#.

Given that 5 x 10 x 2 = 100 cubic feet, divided by 27 = 3.70 cubic yards.

This means the trailer will hold 3.70 yards of material if loaded even with the sides.

- Now we fill it even with the sides with 3/4" gravel -

3.70 x 2200 = 8140#. This is an overload of about 4890#, or 150%!

**Example 2**

A 6x12 tandem axle dump has a 9990# GVWR, 24” sides, and an estimated payload of 7390#.

Given that 6 x 12 x 2 = 144 cubic feet, divided by 27 = 5.33 cubic yards.

This means the trailer will hold 5.33 yards of material if loaded even with the sides.

- Let's fill it with gravel -

5.33 x 2200 = 11,726#. This is an overload of about 4336#, or about 59%!

**Example 3**

A 7x14 tandem axle dump with a 14000# GVWR, 24” sides, and an estimated payload of 9640#.

7 x 14 x 2 = 196 cubic feet, divided by 27 = 7.26 cubic yards.

This means the trailer will hold 7.26 yards of material if loaded even with the sides.

- gravel -

7.26 x 2200 = 15,972#. This is an overload of about 6332#, or about 66%!

With this in mind, dump trailers should be loaded based on **weight** not volume. When figuring out the maximum capacity of a dump trailer, calculate the material's weight. There are resources on the internet that can help you with your estimate. Use the scale at your local gravel pit. If you are unsure of the material's weight, make an extra trip or take less material. Beyond prolonging the life of your trailer, your life and the people’s lives around you may depend on it.