A gravel / mulch calculator converts area and depth into cubic yards (or cubic metres) of bulk material to order. The Toolenza calculator handles rectangular, triangular, and circular shapes, with conversions to cubic feet and bags (for small jobs).

Standard order units

• Bulk delivery — sold by the cubic yard. One yard ≈ 27 cu ft. Spread over an area at typical landscape depths:
  • 2 in deep — covers 162 sq ft per yard
  • 3 in deep — covers 108 sq ft per yard
  • 4 in deep — covers 81 sq ft per yard
• Bagged — typical bag is 2 cu ft of mulch (about 13.5 bags per cubic yard) or 0.5 cu ft of gravel/sand.

Depth recommendations

• Mulch around plantings — 2 to 3 inches. Deeper smothers roots; shallower lets weeds through.
• Mulch in pathways — 4 inches. Compacts to ~3 over time.
• Decorative gravel — 2 to 3 inches over weed-block fabric.
• Driveway gravel base — 4 to 6 inches of crushed stone, compacted, with 2 inches of finer top dressing.
• Playground chip cushioning — 9 to 12 inches uncompacted (codes vary by fall height).

Order quantity math

Square footage × depth (in feet) ÷ 27 = cubic yards. A 20 × 30 ft area at 3-inch depth: 600 × 0.25 / 27 ≈ 5.6 yards. Round up. Add 5–10% for settling and irregular ground.

Bulk vs bag economics

Bulk wins above ~3 yards. Below that, bag costs roughly the same total but spares the delivery fee, lets you pace the project, and means no leftover pile. The break-even depends on local delivery minimums and bag pricing — check both.

Pitfalls

• Weight varies wildly by material. A cubic yard of mulch ≈ 800 lb. Pea gravel ≈ 2,800 lb. Crushed stone ≈ 2,700 lb. Wet sand ≈ 3,000 lb. The truck's load rating matters more than the volume.
• Don't pile mulch against trunks. "Mulch volcanoes" hold moisture against the bark and rot the tree. Keep a 3-inch gap.