Mulch, Topsoil and Gravel by the Cubic Yard
Bulk landscape material is priced by the cubic yard, measured in square feet and spread in inches. A single constant connects all three, and it is the only piece of arithmetic the job needs.
One formula covers mulch, topsoil and gravel
Bulk landscape material is sold by the cubic yard, but you measure your yard in square feet and think about coverage in inches. The bridge between them is a single constant.
500 sq ft at 3 in → 4.63 cubic yards
The 324 is not arbitrary. There are 27 cubic feet in a cubic yard, and 12 inches in a foot, so 27 × 12 = 324. Every mulch, topsoil and gravel estimate you will ever do is that one division.
Cubic yards by area and depth
| Area | 2 in | 3 in | 4 in | 6 in |
|---|---|---|---|---|
| 100 sq ft | 0.62 | 0.93 | 1.23 | 1.85 |
| 200 sq ft | 1.23 | 1.85 | 2.47 | 3.70 |
| 300 sq ft | 1.85 | 2.78 | 3.70 | 5.56 |
| 500 sq ft | 3.09 | 4.63 | 6.17 | 9.26 |
| 800 sq ft | 4.94 | 7.41 | 9.88 | 14.81 |
| 1,000 sq ft | 6.17 | 9.26 | 12.35 | 18.52 |
| 1,500 sq ft | 9.26 | 13.89 | 18.52 | 27.78 |
Suppliers usually sell bulk in half-yard or full-yard increments, so round up. Ordering 4.63 yards means buying 5.
Bags or bulk?
Bagged material is convenient and almost always more expensive per unit of volume. The conversion is worth knowing before you compare prices.
| Bag size | Bags per cubic yard |
|---|---|
| 0.75 cu ft | 36 |
| 1.5 cu ft | 18 |
| 2 cu ft | 13.5 |
| 3 cu ft | 9 |
The crossover is usually somewhere around two to three cubic yards. Below that, bags win on convenience and no delivery fee. Above it, bulk delivery is normally cheaper even after the haulage charge — and you avoid stacking 40 plastic bags in the driveway.
Weight matters more than you think
Volume tells you what to order. Weight tells you whether your vehicle can carry it.
| Material | Approx. weight per cubic yard | Notes |
|---|---|---|
| Bark or wood mulch | 400–800 lb | Doubles when soaked |
| Compost | 1,000–1,600 lb | Varies with moisture |
| Screened topsoil | 2,000–2,700 lb | Wet soil is far heavier |
| Gravel or crushed stone | 2,400–2,900 lb | About 1.35 tons |
| Sand | 2,600–3,000 lb | Heaviest common material |
A half-ton pickup is legally over its payload with roughly one cubic yard of wet topsoil. Gravel for a 500 sq ft driveway at 4 in deep is about 6.17 cubic yards, or over 8 tons — a delivery job, not a trailer job. Work out your own quantities in the mulch calculator, the topsoil calculator or the gravel calculator.
How deep should each material go?
- Mulch: 2–3 in. Deeper suppresses weeds no better and can starve roots of air. Keep it pulled back from trunks and stems — piling mulch against bark invites rot and rodents.
- Topsoil for a new lawn: 4–6 in. Anything under about 4 in gives grass roots nowhere to go in a dry summer.
- Topsoil top-dressing: 1/4–1/2 in. A thin skim over existing turf, not a layer.
- Gravel driveway: 4–6 in total. Laid in two compacted lifts over a base, not one deep pour.
- Gravel path: 2–3 in. Over landscape fabric to stop it disappearing into the soil.
Sod is the exception
Sod is sold by area, not volume, so the 324 formula does not apply. Rolls and slabs vary by region, but a pallet typically covers around 450 square feet. Add 5–10% for cuts around beds, paths and curves, and order it to arrive the day you intend to lay it — stacked sod on a warm pallet starts to fail within about 24 hours. The sod calculator handles the pallet rounding.
If your project also involves a concrete pad or footing, the same volume logic runs through bags of concrete for a slab.
Run your own numbers
FAQ
How do I convert square feet to cubic yards?
How many bags of mulch make a cubic yard?
How deep should mulch be?
How much does a cubic yard of topsoil weigh?
How much gravel do I need for a driveway?
Sources
Primary references used for the figures and rules on this page.
- Yard and garden guidance on mulching, soils and lawn establishment — University of Minnesota Extension