Figuring out how much material to buy is the first—and most common—question we hear at the yard. The short answer: multiply your area's length by width (in feet) by the depth (in inches), then divide by 324. That gives you the number of cubic yards you need. A 10 ft × 10 ft bed at 3 inches deep works out to about one cubic yard.
Order too little and you pay a second delivery fee. Order too much and you've paid for material you can't use. This guide gives you the exact formula, a coverage chart by depth, and worked examples so you can order rock, gravel, soil, or mulch once and get it right.
Key Takeaways
- The formula: cubic yards = (length ft × width ft × depth inches) ÷ 324.
- Rule of thumb: one cubic yard covers about 100 sq ft at 3 inches deep.
- Typical depths: 2–3 inches for decorative rock and mulch; 3–4 inches for pathways; ~4 inches of compacted base rock under pavers.
- Add 5–10% for settling, spillage, and uneven ground.
- Weight matters: a yard of rock can top 2,500 lb—often more than a light truck should carry. Delivery is usually the safer, cheaper choice for bulk.
The Formula: How to Calculate Cubic Yards
Bulk landscape material is sold by the cubic yard—a volume measuring 3 ft × 3 ft × 3 ft, or 27 cubic feet. To find how many yards your project needs:
Cubic yards = (length in feet × width in feet × depth in inches) ÷ 324
That single divisor of 324 does two conversions at once (inches to feet, and cubic feet to cubic yards), so you don't have to. Prefer to skip the math? Our material estimator and coverage calculator do it for you—just enter your dimensions and depth.
For a circular area (like a tree ring or fire-pit surround), first find the area with 3.14 × radius × radius, then multiply by depth in inches and divide by 324.
Coverage Chart: How Much Area One Cubic Yard Covers
Because coverage depends entirely on depth, this chart is the fastest way to sanity-check an order. One cubic yard covers:
| Depth | Coverage (1 cubic yard) | Common use |
|---|---|---|
| 1 inch | ~320 sq ft | Light top-dressing |
| 2 inches | ~160 sq ft | Decorative rock, refreshing mulch |
| 3 inches | ~108 sq ft | Standard mulch and rock ground cover |
| 4 inches | ~80 sq ft | Pathways, paver base, driveway rock |
| 6 inches | ~54 sq ft | Deep fill, raised beds |
Learn more about how depth and density affect this in our material coverage glossary entry.
Worked Examples
Example 1 — A mulch bed. You're mulching a 20 ft × 15 ft bed (300 sq ft) at 3 inches deep: (300 × 3) ÷ 324 = 2.8 cubic yards → order 3 yards.
Example 2 — A gravel pathway. A 40 ft × 3 ft path (120 sq ft) of pea gravel at 2 inches: (120 × 2) ÷ 324 = 0.74 cubic yards → order 1 yard.
Example 3 — A paver patio base. A 12 ft × 12 ft patio (144 sq ft) needs 4 inches of compacted base rock: (144 × 4) ÷ 324 = 1.8 cubic yards → order 2 yards. (Add a little extra; base rock loses volume as it's compacted.)
How Much Does It Weigh? Planning Your Haul
Volume tells you how much to buy; weight tells you how to get it home. A cubic yard isn't a fixed weight—it changes with the material:
| Material | Approx. weight per cubic yard | Approx. tons |
|---|---|---|
| Bark / mulch | 400–800 lb | 0.2–0.4 |
| Topsoil / compost (dry) | 1,000–1,800 lb | 0.5–0.9 |
| Sand | 2,400–2,900 lb | 1.2–1.45 |
| Rock / gravel | 2,400–3,000 lb | 1.2–1.5 |
This is why tons and cubic yards aren't interchangeable. A half-ton pickup can usually carry a full yard of bark but only about half a yard of rock by weight. When in doubt, let us deliver—it protects your vehicle and is almost always cheaper per yard than hauling multiple bagged loads.
Bulk vs. Bagged: Which Is Cheaper?
A cubic yard equals roughly 13–14 standard 2-cubic-foot bags. Once your project needs about half a yard or more, buying in bulk is dramatically cheaper and creates far less plastic waste. Bags only win for very small jobs, tight access, or when you need an exact, portable amount.
Step-by-Step: Ordering the Right Amount
- Measure the length and width of each area in feet (break odd shapes into rectangles and add them up).
- Choose a depth based on use (see the chart above).
- Apply the formula or use our estimator.
- Add 5–10% for waste and settling.
- Check weight against your vehicle, or book delivery.
- Call us at (916) 783-9177 if you'd like a second set of eyes on the numbers.
Related Resources
- Cubic Yard — what it is and how it's measured
- Material Coverage explained
- Bulk vs. Bagged Materials
- River Rock vs. Pea Gravel: which to choose
- Base Rock vs. Drain Rock
- Browse Aggregates & Sands and Decorative Rocks
- Material Estimator · Delivery & Rates
Conclusion: Measure Once, Order Once
Getting quantities right comes down to one formula—(length × width × depth) ÷ 324—plus a small buffer for waste. Match your depth to the job, double-check the weight before you load a truck, and lean on bulk delivery for anything beyond a small bed.
Still unsure? Send us your measurements or use the material estimator, and our team will confirm exactly how much you need. Contact us or call (916) 783-9177—we deliver throughout Roseville and Placer County.
