Hi Jackie,

It depends on the type of gravel you are transporting. On the SImetric site they list the densities of dry materials and they have densities in Kilograms per cubic meter for 4 types of gravel.

First you need to convert 7 tons to kilograms. I asked Google. I typed 7 tons in kilograms into Google and received 7 short tons = 6 350.29318 kilograms. Divide this number by the density of the gravel from the SImetric site to obtain the volume in cubic meters.

I hope this helps,
Penny