At 100 lb/ft³, one ton of sand is about 0.74 cubic yards, and one cubic yard is about 1.35 tons.
Suppliers quote bulk sand either by the ton or the cubic yard, and mixing them up throws an order off by a third. At 100 lb/ft³, one ton is about 0.74 cubic yards — this view makes the round-trip conversion the main answer.
Why order extra? The headline number is the exact material your project needs. When you actually order, add about 5–10% on top — the “with 5% waste” figure in the result is a safe starting point. That margin covers what you lose to compaction, cuts around edges and corners, and ordinary spillage during handling. It is cheaper to have a little left over than to stop mid-job and wait on a second delivery.