The 12-Inch Trap: Why Inches-to-Feet Errors Cost $900 per Concrete Truck
A concrete truck carries 10 yards = 270 cubic feet. The truck costs roughly $1,500—2,000 per load (including the concrete, the delivery, and the driver's time to wash out the chute). If you order concrete by cubic feet when the supplier sells by cubic yards, you will be 27× off —either over-ordering by a factor of 27 (a $40,000 order for a $1,500 patio) or, more commonly, under-ordering by typing inches directly into the formula and dividing by 27 as if the inches were feet. A 20×20 patio, 4 inches thick, calculated as 20 × 20 × 4 ÷ 27 = 59.3 yards —an order for six fully loaded concrete trucks, $9,000 of concrete, when the actual requirement is 5 yards. The dispatcher catches this. The homeowner who orders online without speaking to a dispatcher does not. The inches-must-become-feet rule is the single most important instruction on this page. 4 inches = 0.333 feet. Not 4. Never 4.
How Many Wheelbarrows in a Cubic Yard?
A typical contractor's wheelbarrow holds 6 cubic feet when filled level. 27 ÷ 6 = 4.5 wheelbarrows per cubic yard. In practice, one wheelbarrow load is 2— cubic feet —not 6 —because a full 6-cubic-foot wheelbarrow of wet concrete weighs about 900 lb and cannot be pushed by one person. A cubic yard of concrete (4,000 lb) moved by wheelbarrow is roughly 15—8 trips. This is why concrete is pumped through a hose whenever the pour site is more than 20 feet from the truck. The wheelbarrow is the limiting factor. The cubic yard is the truck's unit. The cubic foot is the shovel's unit —one shovel of concrete is about 0.1—.15 cubic feet, meaning a cubic yard is roughly 200—70 shovelfuls. Nobody hand-mixes a cubic yard of concrete. The cubic yard is the smallest unit of mechanized concrete delivery. For the fundamentals and the integer 27, see the companion page: cubic yards to cubic feet.
yd³ = ft³ ÷ 27 | yd³ = (L × W × H in feet) ÷ 27
Common Cubic Feet to Cubic Yards
| Cubic Feet | Cubic Yards | What it represents |
|---|---|---|
| 1 ft³ | 0.037 yd³ | A milk crate. The smallest bag of potting soil at the garden center (1 cu ft bag). |
| 6 ft³ | 0.222 yd³ | A full wheelbarrow. One contractor trip. |
| 13.5 ft³ | 0.5 yd³ | Half a yard —the bucket of a small front-end loader or a 1/2-yard concrete mixer. |
| 27 ft³ | 1 yd³ | The definition. One cubic yard. A washing machine. The smallest delivered concrete order most plants accept. |
| 135 ft³ | 5 yd³ | A typical patio. A 20×20 slab at 4 inches. The most common residential concrete order. |
| 270 ft³ | 10 yd³ | A fully loaded concrete truck. A 20×40 driveway at 6 inches, or a 40×40 foundation at 3 inches. |
Frequently Asked Questions
How do I avoid the inches-to-feet error when calculating cubic yards?
Always convert depth to feet before multiplying. 1 inch = 0.083 ft. 2 inches = 0.167 ft. 3 inches = 0.25 ft. 4 inches = 0.333 ft. 6 inches = 0.5 ft. 8 inches = 0.667 ft. 12 inches = 1 ft. Write the depth in feet on your scratch paper before you multiply anything. The formula is (L in ft) × (W in ft) × (D in ft) ÷ 27. If depth is the only number in inches, you will get a wrong answer —and the error will be a factor of 12 (for the depth term) or worse. The concrete dispatcher will catch a factor-of-12 error. The mulch yard might not —they deliver what you order. For the quick-reference table of inches-to-feet conversions, see the inches to feet converter.
How much does a cubic yard of dirt weigh?
Topsoil: 2,000—,500 lb per cubic yard (dry), up to 3,000 lb when saturated. Fill dirt (compacted): 2,500—,000 lb per cubic yard. A full-size pickup truck (half-ton, like an F-150) can legally carry about 1/2 to 1 cubic yard of topsoil in the bed —1,000—,000 lb —before exceeding its payload capacity. A cubic yard of dirt is heavier than it looks. The bed of a pickup holds about 2— cubic yards when filled level to the bed rails —but at 2,000+ lb per yard, the truck hits its weight limit long before the bed is full. This is why landscape suppliers deliver by dump truck, not by pickup. The volume is in yards. The weight is in tons. The truck's suspension is the limiting factor, not the bed size. For the weight conversions: lbs to tons and kg to lbs.
Engineering Context
The cubic-foot-to-cubic-yard conversion is ÷27, exact, with no decimal uncertainty. In civil engineering takeoffs, earthwork volumes are computed in cubic feet from survey cross-sections (area in ft² × station length in ft) and then divided by 27 for the construction estimate in cubic yards. The same ÷27 step appears in landfill airspace consumption reports, stormwater detention basin volume calculations, and aggregate base-course thickness verification. The cubic yard is the construction unit; the cubic foot is the measurement unit. The bridge is 27. For the forward direction and more construction-volume context: cubic yards to cubic feet. For international earthwork (cubic meters): ft³ to m³. For water and tank volumes: gal to ft³, ft³ to gal.