Estimate gravel, sand, or pea gravel by cubic yards and tons from your area and depth, with a waste factor.
yd³ = (L × W × depth) ÷ 27; tons = yd³ × 1.4
Crushed gravel weighs about 1.4 tons per cubic yard; sand about 1.35; pea gravel about 1.3. Suppliers often sell by the ton.
Driveways typically need 4–6″ of gravel; pathways 2–3″. Order a little extra for an uneven base.
A 10 x 10 ft shed base at 6 inches deep is 50 cubic feet, or 1.85 cubic yards. Crushed gravel weighs about 1.4 tons per cubic yard, so that's about 2.6 tons. With 5% waste for an uneven base, order about 2.7 tons.
Suppliers usually sell by the ton for delivery and by the bag for small jobs. A 50 lb bag holds roughly half a cubic foot, so this job would be about 100 bags — clearly a case for bulk delivery rather than bags.
Densities are industry averages and vary by material and moisture. Confirm the weight per yard with your supplier.
About 1.4 tons for crushed stone, varying with material and moisture.