A cubic yard is a volume equal to 3 feet × 3 feet × 3 feet = 27 cubic feet. Every landscaping and concrete supplier in the US uses it as the standard ordering unit for mulch, gravel, topsoil, sand, and ready-mix concrete. Knowing how to convert your project dimensions into cubic yards lets you order accurately without running short or overspending.
The Conversion Formula
Length (ft) × Width (ft) × Depth (ft) ÷ 27 = Cubic Yards
If your depth is in inches, divide it by 12 first to convert to feet:
Length (ft) × Width (ft) × (Depth in inches ÷ 12) ÷ 27
Or use the simplified shortcut: Length (ft) × Width (ft) × Depth (in) ÷ 324
The 324 constant comes from 12 inches/foot × 27 feet/yard.
Visual Reference Points
A cubic yard is roughly equivalent to:
| Reference | Approximate Volume |
|---|---|
| Large front-load washer | ~1 yd³ |
| Standard wheelbarrow × 7–9 loads | ~1 yd³ |
| 13.5 bags of 2-cu-ft mulch/soil | ~1 yd³ |
| Full-size pickup bed (level full) | ~1–2 yd³ |
| Typical concrete truck payload | ~8 yd³ |
Coverage: What Does 1 Cubic Yard Cover?
| Depth | Area Covered by 1 yd³ |
|---|---|
| 1 inch | 324 sq ft |
| 2 inches | 162 sq ft |
| 3 inches | 108 sq ft |
| 4 inches | 81 sq ft |
| 6 inches | 54 sq ft |
| 12 inches | 27 sq ft |
This table works for any material: mulch, gravel, topsoil, or sand.
Worked Examples
Example 1: Mulch for a 20×15 ft bed at 3 inches
- 20 × 15 = 300 sq ft
- 300 × 3 ÷ 324 = 2.78 cubic yards
- Round up: order 3 cubic yards
Example 2: Topsoil for a new 50×30 ft lawn area at 4 inches
- 50 × 30 = 1,500 sq ft
- 1,500 × 4 ÷ 324 = 18.5 cubic yards
- Add 10% for settling: 20.4 cubic yards
Example 3: Gravel for a 10×20 ft shed pad at 6 inches
- 10 × 20 × 0.5 ÷ 27 = 3.7 cubic yards
- Add 15% for compaction: 4.3 cubic yards
Cubic Yards vs. Other Units
| Unit | Cubic Feet | Cubic Yards | Common Use |
|---|---|---|---|
| 1 cubic inch | 0.00058 | 0.0000215 | Small measurements |
| 1 cubic foot | 1 | 0.037 | Small bags, concrete bags |
| 1 cubic yard | 27 | 1 | Landscaping standard |
| 1 cubic meter | 35.3 | 1.31 | Metric countries |
Weight Per Cubic Yard by Material
Different materials weigh very differently per cubic yard. This matters when loading trucks or comparing delivery fees:
| Material | Weight per Cubic Yard |
|---|---|
| Dry mulch (shredded wood) | 400–800 lbs |
| Wet mulch | 800–1,200 lbs |
| Topsoil | 2,000–2,700 lbs |
| Sand | ~2,700 lbs |
| Pea gravel | ~2,700 lbs |
| Crushed stone | ~3,000 lbs |
| Concrete (wet) | ~4,000 lbs |
A standard pickup truck with a half-ton payload can carry 1–2 cubic yards of mulch or topsoil, but only about half a cubic yard of gravel before exceeding its payload limit. See how-much-does-a-yard-of-gravel-weigh for a full breakdown.
Using Calculators to Skip the Math
The mulch calculator, gravel calculator, topsoil calculator, and raised-bed-soil-calculator all accept square footage and depth and output cubic yards directly, along with bag counts and weight estimates. You do not need to do the unit conversions manually—but understanding what a cubic yard represents helps you verify that the output makes sense before you place an order.
Common Ordering Mistakes
Forgetting compaction factor. When you compact gravel or soil, it shrinks. Add 10–15% to computed volume for granular fill, and up to 20% for topsoil that will settle under watering.
Confusing cubic yards and square yards. A square yard is only a flat area (9 square feet); a cubic yard is volume. Suppliers always quote bulk materials in cubic yards (or tons), never square yards.
Ordering by weight when the quote is by volume (or vice versa). Ask your supplier which unit they use. Some sell mulch by the scoop (1–2 yd³), stone by the ton, and topsoil by the yard. Confirm before ordering.
Not accounting for irregular shapes. Break L-shaped or curved beds into rectangles, calculate each section separately, and add them together. For circular areas: Area = π × radius², then apply the depth formula.
Practical Ordering Guide
For most materials, order in these increments:
| Volume Needed | What to Order |
|---|---|
| Under 0.5 yd³ | Bags from a hardware store (more convenient) |
| 0.5–2 yd³ | Self-haul from a landscape supply yard (1 scoop) |
| 2–5 yd³ | Bulk delivery (1 small truck load) |
| 5+ yd³ | Full truck delivery; negotiate price per yard |
Bulk vs. Bagged: When Each Makes Sense
Bagged products cost significantly more per cubic yard than bulk, but they offer exact portioning, no minimum order, and no delivery charge.
| Material | Bulk price (typical) | Bag cost per yd³ equivalent | Threshold to switch to bulk |
|---|---|---|---|
| Mulch | $25–$45/yd³ | $80–$100 (2 cu ft bags at $6 each) | Over 0.5 yd³ |
| Topsoil | $20–$40/yd³ | $90–$120 (0.75 cu ft bags at $5 each) | Over 0.75 yd³ |
| Gravel | $30–$60/yd³ | $120–$160 (0.5 cu ft bags at $5 each) | Over 0.5 yd³ |
| Concrete sand | $25–$40/yd³ | $100–$130 (50 lb bags at $5 each) | Over 0.5 yd³ |
Prices vary by region and supplier; compare your specific bag price against local bulk pricing. The math almost always favors bulk above 1 cubic yard for mulch and gravel. The exceptions are projects where you need pinpoint amounts with no room for excess, or where a delivery truck cannot access the site.
Calculating Circular and Irregular Areas
For circular features like a round garden bed or tree ring, calculate the area first:
Area = 3.14159 × radius²
Example: a circular bed 10 feet in diameter (5-foot radius):
- Area = 3.14159 × 5² = 78.5 sq ft
- At 3 inches deep: 78.5 × 3 ÷ 324 = 0.73 cubic yards
For L-shaped or irregular beds, split them into rectangles. Calculate each rectangle separately and sum the volumes. Overestimate slightly — most suppliers do not accept returns of bulk material.
For the exact volume of your project, use the calculator for your material type.