🪵 Garden
Mulch & Topsoil Yardage
Work out how many cubic yards, cubic feet or bags of mulch, topsoil, compost or gravel you need. Enter the area and depth, then press Convert.
About the Mulch & Topsoil Yardage
Bulk soil and mulch are sold by the cubic yard: a cube 3 ft on each side, or 27 cubic feet. To cover 500 sq ft at 3 inches deep, convert the depth to feet (0.25 ft) and multiply: 125 cubic feet, or 4.63 cubic yards. Bagged product is usually sold by volume, often 2 cubic feet per bag, so the same job needs about 63 bags.
Weight is the part that catches people out. A cubic yard of mulch weighs roughly 800 lb, but a cubic yard of topsoil can weigh over a ton and gravel closer to 1.4 tons. Check the delivery vehicle's payload and the path to the garden before ordering a bulk load.
How the calculation works
- Volume (ft³) = area (ft²) × depth (ft).
- Cubic yards = cubic feet ÷ 27.
- Bags (2 ft³) = cubic feet ÷ 2.
- Tons = cubic yards × approximate bulk density (tons/yd³).
Reference values
| Material | Approx. weight | 1 cubic yard covers |
|---|---|---|
| Mulch | 0.4 ton/yd³ | 324 sq ft at 1 in |
| Topsoil | 1.2 tons/yd³ | 324 sq ft at 1 in |
| Compost | 0.6 ton/yd³ | 324 sq ft at 1 in |
| Gravel | 1.4 tons/yd³ | 324 sq ft at 1 in |
| Sand | 1.35 tons/yd³ | 324 sq ft at 1 in |
Worked example: a 20 × 10 ft bed
A 20 × 10 ft bed at 2 inches deep needs 200 × 0.167 = 33.3 ft³, or 1.23 yd³. At 2 ft³ per bag, that is 17 bags. For topsoil at about 1.2 tons per cubic yard, 1.23 yd³ weighs about 1.48 tons—check the delivery vehicle's payload and the path to the garden before ordering a bulk load.
Mulch is usually applied 2–3 inches deep. More than 4 inches can smother roots and hold too much moisture; less than 2 inches does not suppress weeds well. Keep mulch a few inches away from trunks and stems to avoid rot and pest damage.