Decode aggregate numbering, pick the right stone for base, drainage or decorative use, and convert cubic yards to the tons your quarry actually invoices.
Clean stone has no fines: it drains freely, locks by angularity, and never truly compacts to a hard shell. Dense-graded stone contains fines that fill voids and compact into a load-bearing slab, but it holds water. Use dense-graded material under driveways and patios in well-drained soils, and open-graded #57 with geotextile where water must move through the section — the standard approach for permeable pavement and for patios over clay.
Rounded stone never interlocks. Pea gravel and river rock are surfacing and drainage materials, never base.
Quarries sell by the ton. Multiply cubic yards by the bulk density: 1.35 for pea gravel, 1.40 for #57 and decomposed granite, 1.45 for crusher run, 1.30 for river rock. A 4 inch deep, 400 sq ft parking pad is 133 cubic feet, or 4.9 loose cubic yards; add 20% for compaction and multiply by 1.45 to arrive at about 8.6 tons of crusher run.