Landscaping and sitework materials are bought by the ton or cubic yard. Use the gravel calculator and crushed stone calculator for volume and tonnage (typical aggregate runs about 1.4 tons per cubic yard), the gravel driveway calculator for layered base and surface, the asphalt calculator for hot-mix tonnage, the material tonnage calculator for any density, the square footage calculator for area, and the tank volume calculator for cylinders, spheres, and partial fills.
Read How to Calculate Tank Volume or browse the sitework FAQ (100 answers) for densities, depths, and coverage rules.