The Cubic Yards Calculator converts an area and a depth into cubic yards, the unit that bulk mulch, gravel, topsoil, concrete and road base are sold in almost everywhere in the United States. Enter a length and width or a known area, set a depth in inches or feet, and the result returns cubic yards, cubic feet, cubic metres, coverage at the entered depth, and bag counts for six standard bag sizes.
Calculate cubic yards from area and depth
Bulk material volume is area multiplied by depth, and the only real complication is that area is almost always measured in square feet while depth is almost always specified in inches. The calculator accepts both units directly and performs the conversion internally rather than asking for a pre-converted depth.
Volume (yd³) = (Area (ft²) × Depth (in)) ÷ 324A garden bed, a driveway base and a mulch ring all use this same path. The 324 in that formula is not an arbitrary constant; it comes directly from the size of a cubic yard and the fact that depth is entered in inches rather than feet, and the next section derives it in full.
Convert cubic feet to cubic yards
A cubic yard is a cube measuring one yard, or three feet, on every edge, so its volume in cubic feet is 3 × 3 × 3 = 27. Dividing any cubic-foot volume by 27 gives the equivalent number of cubic yards, and this single division underlies every material calculator on this site that reports a yardage.
Volume (yd³) = Volume (ft³) ÷ 27A volume of 108 ft³ converts to 108 ÷ 27 = 4 yd³. This step is exact, not an approximation, because 27 comes directly from the geometry of a yard rather than from a rounded field measurement. Ready-mix concrete, bulk mulch, gravel and topsoil are all quoted by the cubic yard specifically because a cubic yard is a practical truckload-scale unit, large enough that most residential orders land in the low single digits.
Apply the 324 coverage rule
One cubic yard spread one inch deep covers exactly 324 square feet, and that figure comes directly from combining the 27 cubic feet in a yard with the twelve one-inch slices in a foot of depth. It is the fastest way to sanity-check any depth-based material order without running the full formula.
27 ft³ ÷ (1 ÷ 12 ft) = 27 × 12 = 324 ft²One cubic yard, spread at a one-inch depth, covers a rectangle roughly 18 ft by 18 ft, since 18 × 18 = 324. Halving the depth to a half inch doubles the coverage to 648 ft², and doubling the depth to two inches halves it to 162 ft². The relationship is inverse: coverage falls as depth rises, and the 324 constant is the anchor point every other depth in the table below is derived from.
Estimate a 500 square foot bed at 3 inches
A garden bed measuring 500 ft², filled 3 inches deep, needs 4.63 cubic yards of material. Every step below uses the same 324 constant from the previous section, so the working can be checked by hand. 1. State the known values. Area = 500 ft², Depth = 3 in
2. Multiply area by depth. 500 ft² × 3 in = 1,500
3. Divide by 324. 1,500 ÷ 324 = 4.63 yd³
The same bed at a 2-inch depth would need 500 × 2 ÷ 324 = 3.09 yd³, and at 4 inches it would need 500 × 4 ÷ 324 = 6.17 yd³. Depth moves the order almost as much as area does, which is why the calculator keeps both fields equally prominent rather than treating depth as an afterthought.
Read cubic yard coverage by depth
Coverage per cubic yard falls as depth increases, and this table is the fastest way to estimate a bulk order without running the multiplication for a specific area. Multiply the coverage figure by the number of cubic yards being considered to get the total area that volume will cover at that depth.
| Depth | Coverage per cubic yard |
|---|---|
| 1 in | 324 ft² |
| 2 in | 162 ft² |
| 3 in | 108 ft² |
| 4 in | 81 ft² |
| 6 in | 54 ft² |
| 12 in (1 ft) | 27 ft² |
At 12 inches of depth, one cubic yard covers only 27 ft², the same number as the cubic feet in a yard, because a foot-deep layer one yard square is one cubic yard exactly. This table applies to any bulk material; the density and weight that go with a specific product, such as gravel or topsoil, live on that material's own calculator page.
Convert cubic yards to bags
Bagged material is sold by a fixed bag volume, and dividing a cubic-yard total by that volume gives the bag count directly. Six bag sizes cover nearly everything sold at a retail garden centre or home improvement store.
| Bag size | Bags per cubic yard |
|---|---|
| 0.5 ft³ | 54 |
| 0.75 ft³ | 36 |
| 1 ft³ | 27 |
| 1.5 ft³ | 18 |
| 2 ft³ | 14 |
| 3 ft³ | 9 |
A 3 cubic yard order in 2 ft³ bags needs 3 × 14 = 42 bags, rounded up if the volume is not an exact multiple. Bagged material typically costs more per cubic yard than bulk delivery, often by a factor of two or more, but avoids a delivery minimum, so small orders under about a third of a yard are usually cheaper bagged even before a delivery fee is added.
Order extra for compaction and settling
Geometric volume assumes the material sits exactly as measured, and almost no bulk material does. Loose material compacts under its own weight or under foot and vehicle traffic, and organic material settles further as it breaks down, so the ordered volume needs to exceed the calculated volume to end up with the intended finished depth.
Compaction and settling allowances are material-specific rather than universal. Decorative mulch typically needs 5 to 10 percent added for settling over its first season. Gravel used as a compacted base layer needs 10 to 15 percent or more, since loose gravel loses a meaningful share of its volume the moment a plate compactor runs over it. Each material page on this site, gravel, mulch, topsoil and road base, applies its own default allowance and states the reasoning next to the number rather than burying it in a single adjusted total.
Order volume = Geometric volume × (1 + allowance%)A geometric volume of 4.63 yd³ with a 10 percent allowance becomes 4.63 × 1.10 = 5.09 yd³ ordered. Rounding up to the nearest quarter or half yard that a supplier delivers in is normal practice on top of this figure.
Calculate cubic yards for irregular areas
An irregular bed, a rectangular border strip, or a ring around a tree all reduce to the same two-step process: find the area using the shape that matches the outline, then apply depth using the 324 rule exactly as with a plain rectangle. The area step is the only part that changes.
A rectangular border, a circular ring, an annulus, a trapezoid, or a triangle all have their own area formula, and the Square Footage Calculator carries the full derivation for each one along with worked examples. Once that area figure is in hand, depth converts it to cubic yards exactly as shown above, with no separate formula needed for the irregular shape beyond the area calculation itself. A driveway with a curved apron, for example, is measured as a rectangle plus a triangle or a sector, added into a single area total, then multiplied by depth once.
Frequently asked questions
How many cubic feet are in a cubic yard?
Twenty-seven. A cubic yard is 3 ft on each side, and 3 × 3 × 3 = 27 ft³. Dividing any cubic-foot total by 27 converts it directly to cubic yards.
How much area does one cubic yard cover at different depths?
At 1 inch deep, one cubic yard covers 324 ft². At 2 inches it covers 162 ft², at 3 inches 108 ft², at 4 inches 81 ft², at 6 inches 54 ft², and at 12 inches 27 ft². Coverage is inversely proportional to depth: doubling the depth halves the area one cubic yard will cover.
How do I convert square feet to cubic yards?
Multiply the square footage by the depth in inches, then divide by 324. A 500 ft² area at 3 inches deep is 500 × 3 ÷ 324, or 4.63 cubic yards. If the depth is already in feet, multiply area by depth in feet, then divide by 27 instead.
How many bags equal a cubic yard?
It depends on the bag size. A cubic yard takes 54 bags at 0.5 ft³ each, 36 bags at 0.75 ft³, 27 bags at 1 ft³, 18 bags at 1.5 ft³, 14 bags at 2 ft³, or 9 bags at 3 ft³. Check the bag label for its stated cubic-foot volume before multiplying.
Why does depth need to be in inches for the 324 formula?
The 324 constant is built specifically around an inch-based depth; it comes from 27 cubic feet divided by one-twelfth of a foot. If depth is entered in feet instead, divide the area-times-depth product by 27 rather than 324. Mixing the two, dividing an inch-based depth by 27, is the single most common hand-calculation error on this type of order.
How much extra should I order for compaction or settling?
Five to ten percent for material that only settles, such as decorative mulch, and 10 to 15 percent or more for material that is actively compacted, such as a gravel base layer. The exact figure depends on the material; each material calculator on this site states its own default and the reasoning behind it.
How do I calculate cubic yards for an irregular-shaped bed?
Find the total area first, using whichever shape or combination of shapes matches the outline, then apply the depth using the same 324 rule as a rectangle. The Square Footage Calculator covers rectangles, circles, triangles, trapezoids and borders for the area step.
How many tons is a cubic yard of material?
It depends entirely on the material's density, which is not a fixed number across products. A cubic yard of mulch weighs roughly 400 to 800 lb depending on type, while a cubic yard of gravel or topsoil weighs 2,000 lb or more. Each material's own calculator page applies its specific density to convert yardage into weight.
Can I use this calculator for concrete instead of loose material?
Concrete uses the same area-times-depth-divided-by-324 arithmetic for a flat slab, but the Concrete Calculator adds bag counts, weight and a waste allowance specific to poured concrete, along with shapes such as columns and footings that do not reduce to a single area and depth.
Summary
The Cubic Yards Calculator turns an area and a depth into cubic yards using a single constant: 324 square feet per cubic yard at one inch of depth, derived from the 27 cubic feet in a yard split across twelve one-inch slices.
Coverage falls as depth rises, bag counts scale directly from a cubic-yard total, and compaction or settling allowances belong to the specific material rather than a single universal percentage. Irregular areas resolve through the same formula once their square footage is known, with no separate volume formula required for the shape itself.