See the calculation with sample numbers
400 sq ft at 2 inches deep with 10% extra is about 73.33 cu ft, or 2.72 cu yd. Weight stays blank until you enter a supplier factor.
What can change the result?
Gravel density varies by material, size, and moisture, so this tool never assumes one universal tons-per-yard value.
How this was calculated: Cubic feet/yards, optional tonnage with explicit factor and budget.