Gravel & Mulch Calculator

How the math works

Bulk landscape material is commonly sold by volume — the cubic yard — so every estimate starts with the same two measurements: the area and the planned depth.

Area is plain geometry. A rectangular bed is length × width; a round bed is π × radius². Multiply square feet by depth in feet — inches divided by 12 — for cubic feet, then divide by 27 for cubic yards. If a supplier sells by weight, enter that supplier's tons-per-cubic-yard value and the tool will make the additional conversion.

Why weight needs your supplier's number

The same nominal material can weigh differently by gradation, source, and moisture. A generic density can therefore understate a truck delivery or overstate what a trailer can safely carry. BenchCalcs does not assume one: tonnage stays hidden until you enter the bulk density supplied for the exact material. Use the resulting weight for quote comparison only, and follow vehicle and trailer ratings.

Bags vs. bulk — the real decision

A 2-cubic-foot bag means one cubic yard is 13.5 bags, rounded up when you buy. Whether bulk or bags costs less depends on local price, delivery fees and minimums, so compare the same calculated volume both ways. The tool provides the quantities without inventing a universal break-even point.

How deep, and the coverage number

Depth is where people go wrong. Use the material supplier's or project designer's depth for stone, soil, and structural applications. For mulch, extension guidance generally favors a moderate layer rather than piling material against trunks or stems. The calculator also shows how many square feet one cubic yard covers at your chosen depth (324 ÷ depth in inches): one yard covers about 162 sq ft at 2 inches and 108 sq ft at 3 inches.

A worked driveway example

Say a project plan calls for a uniform 4-inch layer over an area 40 feet long and 12 feet wide. The area is 480 square feet. Four inches is one-third of a foot, so the volume is 480 × 0.333 = 160 cubic feet, or about 5.9 cubic yards. If a supplier quotes by the ton, use its density for that exact aggregate; the calculator will then show the weight. A 200-square-foot mulch bed at 3 inches uses 50 cubic feet, under 2 cubic yards, or 25 two-cubic-foot bags.

One more thing raw volume does not capture is compaction and settlement. Ask the supplier or project designer whether the quoted quantity is loose, compacted, or installed volume and what allowance applies to the exact material and application.

When this calculator is the wrong tool

This covers loose material spread over an area at a roughly uniform depth — beds, paths, driveways, and fill. It does not size a structural driveway base or predict supplier-specific compaction and settlement. For structural base, retaining-wall backfill, or drainage gravel, follow the designed section and material specification.

Volume and bag counts use plain geometry. Optional tonnage appears only when you enter a supplier-provided density.