Cubic Yards Calculator — for gravel, soil, mulch and concrete

How it works

Bulk materials — gravel, topsoil, mulch, sand, concrete — are sold by the cubic yard. To find how many you need, work out the volume of the space and convert to cubic yards:

cubic yards = (length ft × width ft × depth ft) ÷ 27

The volume in cubic feet is length × width × depth. Dividing by 27 converts to cubic yards, because one yard is 3 feet, so one cubic yard is 3 × 3 × 3 = 27 cubic feet (NIST). Depth is usually given in inches for a material layer, so this calculator divides the depth by 12 to convert it to feet first.

Order a little extra — bulk materials settle and spread unevenly, so rounding the cubic yards up (or adding about 5–10%) avoids coming up short.

Worked example

A 10 × 10 ft area filled 6 inches deep is 10 × 10 × 0.5 = 50 cubic feet, which is 50 ÷ 27 = 1.85 cubic yards. A 3-foot cube (3 × 3 × 3 ft, i.e. a 36-inch depth) is exactly 27 cubic feet = 1 cubic yard — the definition. A wider 20 × 20 ft area 4 inches deep comes to about 4.94 cubic yards.

Frequently asked questions

How many cubic feet are in a cubic yard?

Exactly 27. A yard is 3 feet, so a cubic yard is 3 × 3 × 3 = 27 cubic feet. To convert cubic feet to cubic yards, divide by 27; to go the other way, multiply by 27.

How do I calculate cubic yards for a project?

Multiply the length, width and depth in feet to get cubic feet, then divide by 27. If the depth is in inches (like "4 inches of gravel"), divide it by 12 first to convert to feet. This calculator does that step for you.

Why is depth entered in inches?

Because material layers are almost always specified in inches — 2 inches of mulch, 4 inches of gravel, a 4-inch concrete slab. Entering inches is more natural; the calculator converts to feet (÷12) before working out the volume.

How much extra material should I order?

Add roughly 5–10% to the calculated cubic yards. Bulk materials compact when delivered and spread unevenly, and it is cheaper to have a little left over than to reorder. For a critical pour like concrete, round up to the next quarter or half yard.

How do cubic yards relate to tons or bags?

It depends on the material's density. Gravel and soil are often sold by weight, so you multiply the cubic yards by the material's tons-per-cubic-yard; bagged materials divide the cubic feet by the bag size. The dedicated gravel, mulch and concrete calculators handle those conversions.

What if my area is not rectangular?

Break it into rectangles, find the cubic yards for each, and add them up. For a circular area, the volume is π × radius² × depth; convert that to cubic yards by dividing the cubic feet by 27.