How it's calculated
yd³ = (area × depth) ÷ 324
area in square feet, depth in inches. 324 = 12 in/ft × 27 ft³/yd³, converting ft²·in directly to cubic yards.
Common questions
How do square feet become cubic yards?
Multiply the area by the depth to get cubic feet, then divide by 27, since a cubic yard is 27 cubic feet.
Why add a 10 percent buffer?
Material settles, spills, and never spreads perfectly even, so a small surplus keeps you from running short.