Cubic Yard Calculator

Getting the Volume — and the Order — Right

Why everything divides by 27

A cubic yard is a cube three feet on every side, and three times three times three is 27 — so there are 27 cubic feet in one cubic yard. That single number is the pivot every material calculation turns on. You measure your space in feet (length and width) and usually in inches (depth, since most pours and spreads are just a few inches), convert the depth to feet by dividing by 12, multiply the three dimensions to get cubic feet, then divide by 27 to reach cubic yards. The mixed units trip people up constantly: a 4-inch slab isn't 4 feet deep, it's 0.33 feet deep, and forgetting that inch-to-foot conversion inflates your order twelvefold. Do the conversion first, every time, and the rest is straightforward multiplication.

The reason cubic yards matter at all is that bulk landscaping and construction materials — concrete, topsoil, gravel, mulch, sand — are sold by the yard, not the bag, once you need more than a trivial amount. A pickup truck bed holds roughly two to three cubic yards depending on the truck; a dump-truck delivery starts around 10. Knowing your yardage is how you know whether you're making a hardware-store run or scheduling a delivery, and it's how you avoid the two expensive mistakes at either end: ordering short and paying a second delivery fee, or ordering long and paying to haul away a pile you didn't need.

Waste allowance: the number that saves the job

The waste allowance is small but it prevents the single worst outcome in any pour or fill — running out partway. Concrete is unforgiving here: once a pour starts, a cold joint forms if you stop to wait for a second load, permanently weakening the slab, and ready-mix has a delivery minimum and a short working time. That's why professionals add 5–10% to concrete orders and simply round up to the next quarter-yard. For soil and mulch the stakes are lower but the logic holds: ground isn't perfectly level, edges get bermed, and freshly delivered soil settles and compacts, so a bed that measures 2.5 yards flat often swallows closer to 2.75 once you're actually spreading it. Gravel and base material compact even more — expect to add 15–20% for compaction on a driveway base, because the loose volume delivered shrinks under a plate compactor.

The right allowance depends on the material and the surface. Flat, contained spaces (a form-boarded slab, a raised bed with fixed walls) need only 5%. Irregular ground, sloped sites, or anything you'll compact wants 10–20%. The calculator defaults to 10% as a sensible middle, but bump it up for gravel bases and rough terrain, and trim it toward 5% for a clean, formed, level pour where you can measure precisely.

Coverage per cubic yard: a reference grid

One cubic yard spreads differently depending on depth. This grid shows how far a single yard goes across common materials and thicknesses, so you can sanity-check your order before it arrives.

The formula behind every row is 324 ÷ depth-in-inches, since a cubic yard is 27 cubic feet and each square foot at one-inch depth uses 1/12 of a cubic foot. The gravel column runs lower because compaction shrinks loose volume 15–20% — order that much extra for any base you'll run a plate compactor over.

Bags versus bulk: where the crossover sits

The calculator shows an equivalent bag count because there's a real decision point between bagged and bulk material, and getting it wrong is costly in both directions. A standard 60-pound bag of concrete mix yields about 0.45 cubic feet; an 80-pound bag about 0.6. It takes roughly 45 sixty-pound bags to make a single cubic yard — which is why bulk ready-mix wins decisively above about one yard. Below half a yard, bags win: no delivery fee, no minimum, no waste, and you mix only what you need. The awkward middle — half a yard to a full yard — is a genuine judgment call weighing the delivery fee and minimum against the labor and cost of hauling and mixing 25 to 45 bags by hand.

For soil and mulch the crossover comes much sooner because bagged versions are expensive per unit. Bagged mulch runs two to three times the price of bulk by volume, so anything beyond a few cubic feet — say, more than about 10 bags — usually favors a bulk delivery if you can get a truck to your site. The convenience of bags is real for small, tidy jobs and awkward-access yards; the savings of bulk are real the moment volume climbs. The bag count here is your reality check: if the calculator says you'd need 60 bags, that's a bulk delivery wearing a disguise.

Frequently asked questions

How many cubic feet are in a cubic yard?

Exactly 27 — a cubic yard is 3 feet by 3 feet by 3 feet. This is the conversion every bulk-material calculation uses: figure your volume in cubic feet, then divide by 27 to get yards. Remember to convert depth from inches to feet first (divide by 12), since that mixed-unit step is where most errors creep in.

How much concrete does a cubic yard cover?

One cubic yard covers 81 square feet at 4 inches thick, 65 square feet at 5 inches, or 54 square feet at 6 inches. The math is simply 324 divided by the thickness in inches (since a yard is 27 cubic feet and there are 12 inches per foot). A typical two-car driveway at 4 inches runs 6–8 yards.

How many bags of concrete equal a cubic yard?

About 45 sixty-pound bags or 60 forty-pound bags per cubic yard — 60-pound bags yield roughly 0.45 cubic feet each. That's why anything over about a cubic yard is far cheaper and faster as bulk ready-mix delivery. Below half a yard, bags usually win on cost and convenience once you factor in delivery minimums.

How do I calculate cubic yards for an irregular area?

Break the space into rectangles and triangles, calculate each piece separately, and add them up. For circles, use π × radius² for the area, then multiply by depth. Round everything up slightly and add a waste allowance — irregular jobs almost always need more material than a clean measurement suggests, because edges and uneven ground eat volume.

Should I round up my concrete order?

Yes, always — round ready-mix up to the next quarter-yard and add 5–10% waste. Running short mid-pour creates a cold joint that permanently weakens the slab, and a second delivery carries its own minimum and fee. A little leftover concrete is cheap; a short load is expensive and can compromise the whole job. Over-ordering slightly is the professional default.