Pea gravel spreads well at about 2 inches deep; the tool defaults to that and uses a 100 lb/ft³ density.
Pea gravel spreads thin — about 2 inches for a path or patio — and this view defaults to that depth. Because it's rounded, keep it off driveways where tires roll; it shifts and ruts under vehicle weight.
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.