Volume basics
How Big Is a Cubic Yard?
One cubic yard is the space inside a cube three feet on each side. Here is what that means on the ground, in bags, and on a supplier’s quote.
By Kumar Baniya, MEng in Structural Engineering (University of Leeds) · Last reviewed
The definition
A yard is 3 feet, so a cubic yard is a cube 3 ft long, 3 ft wide and 3 ft high. Multiply the sides and you get 3 × 3 × 3 = 27 cubic feet. Because the international yard is defined as exactly 0.9144 m, a cubic yard is exactly 0.764555… cubic meters — about 0.765 m³, or 764.6 liters.
| Unit | One cubic yard equals |
|---|---|
| Cubic feet | 27 ft³ |
| Cubic inches | 46,656 in³ (36 × 36 × 36) |
| Cubic meters | 0.7646 m³ |
| Liters | 764.6 L |
Picturing one on the ground
Mark out a square 3 ft by 3 ft (about 91 cm each way) with a tape measure and imagine the material stacked evenly to 3 ft high. That block is one cubic yard. In practice material is rarely piled that way: it is spread thinly over a much larger area, which is why the depth matters so much.
How far a cubic yard spreads
Spread evenly, the area a cubic yard covers is 27 ft³ divided by the depth in feet. With depth in inches the shortcut is 324 ÷ depth, because 27 × 12 = 324.
| Depth | Area covered | About the size of |
|---|---|---|
| 1 in | 324 sq ft | a square about 18.0 ft on each side |
| 2 in | 162 sq ft | a square about 12.7 ft on each side |
| 3 in | 108 sq ft | a square about 10.4 ft on each side |
| 4 in | 81 sq ft | a square about 9.0 ft on each side |
| 6 in | 54 sq ft | a square about 7.3 ft on each side |
These figures are pure geometry, before any allowance or settling. They show the arithmetic; they are not recommended depths. A worked check: a 12 ft × 9 ft bed at 3 in is 12 × 9 × 3 ÷ 324 = exactly 1 cubic yard.
Cubic yards and bags
Bags are labelled by volume. Divide 27 ft³ by the bag volume, then round up because you cannot buy part of a bag:
| Bag size | Bags in 1 yd³ | Whole bags to buy |
|---|---|---|
| 1 ft³ | 27.00 | 27 |
| 1.5 ft³ | 18.00 | 18 |
| 2 ft³ | 13.50 | 14 |
| 3 ft³ | 9.00 | 9 |
| 40 L | 19.11 | 20 |
For bagged concrete, use the manufacturer’s stated yield — the volume of mixed concrete one bag makes — not the dry bag weight. The concrete calculator shows yields for products we have verified.
A quick way to sanity-check an order
If a quote or a calculation looks wrong, reverse it: multiply the cubic yards you are about to order by 324, then divide by your depth in inches. The answer is the square footage that order will cover. If that is far from the area you measured, check your units — a depth entered in feet instead of inches is the most common slip.
Volume is not weight
A cubic yard is always 27 ft³, but how much it weighs depends on what fills it. Mulch, soil and stone weigh very different amounts for the same volume, and moisture changes the figure again. To estimate weight you need the supplier’s bulk density — see why cubic yard weight varies and the cubic yards to tons calculator.