To be effective as horse you need a 3" - 6" layer of pea gravel. The deeper the material the more the stones are able to "do their job" and slightly shift while the horse is standing, walking and bedding down. How much Pea Gravel will you need? To determine how many yards of pea gravel you need for your area, use the calculator link below to convert your measurements into yards needed. Hit your back button to return to this page. CONVERSION CALCULATOR Now that you know how many yards you need here is how you convert this to tons. Take your total cubic yards x 3000. Now divide this number by 2000 and you have how many tons you need for your project. Our dump trucks carry 15 to 23 tons per load.