Material Coverage
Also known as: coverage rate, how much material do I need
Material coverage is how much area a given volume of material covers at a chosen depth. As a rule of thumb, one cubic yard covers about 100 square feet at 3 inches deep.
In simple terms
Coverage answers the question "how much do I need?" You take the area you want to cover and the depth you want, and the coverage rate tells you how many cubic yards (or bags) to order.
In depth
The formula is: cubic yards = (length ft × width ft × depth in inches) ÷ 324. The divisor 324 already converts inches to feet and cubic feet to cubic yards. Coverage shifts with material density and how it settles: angular gravel and compacted base cover slightly less after tamping, while fluffy bark covers a bit more before it settles. Always round up and add about 5–10% for waste and uneven ground.
Why it matters
Getting coverage right prevents the two most common ordering errors — a second delivery fee because you ran short, or paying for material you cannot use.
Common mistakes
- Forgetting to convert depth from inches to feet, which throws the math off by a factor of 12.
- Ordering the exact calculated amount with no waste allowance for settling, spillage and uneven grade.
Examples & uses
- A 200 sq ft patio base at 4 inches deep: (200 × 4) ÷ 324 ≈ 2.5 cubic yards.
- A 400 sq ft mulch bed at 3 inches: (400 × 3) ÷ 324 ≈ 3.7 cubic yards — order 4.