Mulch, Soil and Gravel Calculator: Cubic Yards, Bags and Tons

The formula

Every bulk material calculation comes down to the same three steps:

1. Area in square feet × depth in inches ÷ 12 = cubic feet.
2. Cubic feet ÷ 27 = cubic yards (a cubic yard is 3 × 3 × 3 feet).
3. Cubic feet ÷ bag size = number of bags, rounded up.

For example, a bed of 200 square feet at 3 inches deep is 200 × 3 ÷ 12 = 50 cubic feet. That is 1.85 cubic yards in bulk, or 25 bags of 2 cubic feet.

Coverage table for one cubic yard

How deep to spread each material

Mulch. University of Illinois Extension recommends 2 to 4 inches in well-drained areas: 2 to 3 inches for fine composted materials and 3 to 4 inches for coarse mulches. Keep mulch at least 4 inches away from tree trunks and stems. More on this in our mulch depth guide.

Topsoil and compost. The depth depends on the job: a thin topdressing over a lawn, a few inches mixed into a bed, or more to fill a raised bed or level a low spot. Measure the depth you actually need to fill rather than guessing; for raised beds, measure the inside height of the frame.

Gravel. Paths, patios and driveways usually have a base specification from the product or contractor. For patio pavers, the industry minimum base is covered in our paver patio calculator.

Bulk or bags?

Bags are easy to carry and store and suit small jobs. Bulk delivery is usually cheaper per cubic yard for larger areas but often comes with a delivery charge and a minimum order. A simple way to compare: divide the bulk price plus delivery by the number of cubic yards, and compare it with the bag price times 13.5 (for 2 cubic foot bags). Prices vary widely by region and season, so get current quotes.

Gravel by the ton

Quarries and landscape yards often sell stone by weight. To convert cubic yards to tons you need the weight per cubic yard for that specific product, which varies with the type of stone, its size, its moisture and whether it is measured loose or compacted. Enter your supplier's figure in pounds per cubic yard and the calculator converts (2,000 lb = 1 ton).

Measuring tips

• Measure beds at their widest points and break odd shapes into rectangles, triangles and circles. See the measuring guide.
• If you are topping up existing mulch, measure how deep the old layer still is and only add the difference.
• Before digging or grading, call 811 to have utilities marked.

Common questions

How many bags of mulch are in a cubic yard?

A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cubic feet or 9 bags of 3 cubic feet.

How much area does a cubic yard of mulch cover?

At 3 inches deep, one cubic yard covers 108 square feet. At 2 inches it covers 162 square feet, and at 4 inches 81 square feet.

Why doesn't the calculator give tons by default?

Because the weight of a cubic yard depends on the stone, its size, its moisture and whether it is loose or compacted. Ohio DOT, for example, uses 3,800 lb per cubic yard for one compacted crushed aggregate, while loose stone in a truck weighs less. Your supplier can tell you the figure they use.

Should I order extra?

Bulk mulch and soil settle after spreading, and gravel compacts. Adding 5–10% is common so the finished depth matches your plan.