Ordering concrete by the yard without knowing how many yards you need is one of the more expensive mistakes a homeowner or contractor can make. Order too little and the truck leaves with an unfinished pour. Order too much and you’re paying for material that ends up in a pile on the lawn. Either way, the project gets complicated.
The good news is that figuring concrete yardage is straightforward arithmetic. No specialized knowledge required. You need three measurements, a basic formula, and a few minutes. This guide walks through that formula step by step, covers the shape variations that most projects involve, and answers the questions that come up most often when ordering ready-mix for the first time.
What a Cubic Yard of Concrete Actually Looks Like
Before the math, it helps to have a mental picture of what a cubic yard actually is. A cubic yard is a cube that measures three feet on every side: three feet wide, three feet long, three feet tall. That’s 27 cubic feet of concrete.
In practical terms, that’s enough concrete to cover a significant surface area at typical residential thicknesses. Most people are surprised by how far a single yard actually goes.
How Many Square Feet One Yard Covers
| Slab Thickness | Square Feet Covered Per Cubic Yard |
|---|---|
| 4 inches | 81 square feet |
| 5 inches | 65 square feet |
| 6 inches | 54 square feet |
A 10×10 foot patio at 4 inches thick needs just over 1.2 cubic yards. A 20×30 foot driveway at 5 inches thick needs roughly 9.3 cubic yards before overage. Having these reference points before running the full calculation makes it easy to sanity-check the final number.
The 4-Step Formula for Figuring Concrete Yardage
Every concrete estimate, regardless of project size, runs through the same four steps.
Step 1: Measure Length, Width, and Thickness
Measure the length and width of the area in feet. Measure the planned slab thickness in inches. Write all three numbers down before doing anything else. If the project has irregular dimensions, break it into rectangular sections and measure each one separately.
Step 2: Convert Inches to Feet
Thickness almost always gets measured in inches, but the formula requires everything in feet. Divide the thickness in inches by 12 to get thickness in feet.
Common conversions to keep handy:
- 3.5 inches = 0.29 feet
- 4 inches = 0.33 feet
- 5 inches = 0.42 feet
- 6 inches = 0.5 feet
Step 3: Multiply to Find Cubic Feet
Multiply length × width × depth (all in feet). The result is the total cubic feet of concrete the project requires.
Step 4: Divide by 27 to Get Cubic Yards
Divide the cubic feet total by 27. That’s your cubic yard number. Always round up to the nearest quarter yard when ordering.
Worked example: a 12×16 patio poured 4 inches thick
Length: 12 feet
Width: 16 feet
Depth: 4 inches = 0.33 feet
12 × 16 × 0.33 = 63.36 cubic feet
63.36 ÷ 27 = 2.35 cubic yards
Before adding overage, this 12×16 patio needs approximately 2.35 cubic yards. Round up to 2.5 and add 10 percent for waste: order 2.75 yards, which most suppliers round to 3.
How to Figure Yards for Non-Rectangular Projects
Most residential projects include at least one shape that doesn’t fit neatly into a length-times-width calculation.
Round Patios and Circular Pads
For circular areas, use: 3.14 × radius² × thickness (all in feet) ÷ 27
A 12-foot diameter circular patio at 4 inches thick: radius is 6 feet. 3.14 × 36 × 0.33 = 37.3 cubic feet ÷ 27 = 1.38 cubic yards.
Footings, Piers, and Post Holes
Footings use the same rectangular formula. A continuous footing 40 feet long, 12 inches wide, and 8 inches deep: 40 × 1 × 0.67 = 26.8 cubic feet ÷ 27 = roughly 1 cubic yard.
Post holes use the circular formula. A 12-inch diameter hole, 36 inches deep: 3.14 × 0.25 × 3 = 2.36 cubic feet per hole. Multiply by the number of holes, then divide by 27.
Concrete Steps
Steps get calculated by breaking each step into a rectangular solid: width × depth × height for each step, add them all up, then divide by 27. A 4-foot-wide staircase with three steps at 7 inches tall and 12 inches deep: (4 × 1 × 0.58) × 3 = 6.96 cubic feet ÷ 27 = 0.26 cubic yards just for the steps. The landing pad gets calculated separately.
L-Shaped and Irregular Layouts
For when working with L-Shaped or irregular layouts, you have to divide the space into rectangles. Calculate each rectangle separately using the standard formula, add the cubic footage together, and divide the total by 27. This approach works for L-shaped patios, curved driveway aprons, and any project where a single set of measurements won’t capture the full area.
Adding Extra: How Much Overage to Plan For
A calculated estimate based on perfect measurements is always a starting point, not a final order number. Real-world conditions always consume more concrete than the math alone predicts.
Uneven Subgrade, Forms, and Spillage
The formula assumes a perfectly level subgrade at a consistent depth. In practice, subgrades have low spots, forms flex slightly under the weight of wet concrete, and some material always spills during the pour. All of those factors mean the actual volume used almost always exceeds the calculated volume.
Why Coming Up Short Costs More Than Ordering Extra
Running out of concrete mid-pour creates a cold joint, the visible seam where the first load partially set before the second load arrived. Cold joints are structural weak points and cosmetic problems that are difficult to address after the fact. The cost of a short-load fee or a second delivery almost always exceeds the cost of simply ordering a quarter to half yard extra up front. Order conservatively in one direction: always round up, never round down.
The standard recommendation is to add 5 to 10 percent to any calculated yard figure. For smaller pours under 3 yards, rounding up to the nearest half yard is a reasonable approach. For larger projects, 8 to 10 percent overage is standard practice.
Figuring Yardage for a Stamped Concrete Patio or Driveway
Stamped concrete uses the same yardage formula as standard concrete. The calculation doesn’t change based on the finish. What does change is the importance of getting the number exactly right, and placing the entire order as a single delivery.
Typical Thickness for Stamped Patios, Walkways, and Driveways
Stamped patios are typically poured at 4 inches for residential applications. Stamped driveways for passenger vehicles run 4 to 5 inches. Stamped pool decks are generally 4 inches. Walkways and paths can go as thin as 3.5 inches where vehicle loads aren’t a concern.
Run the standard formula with these thickness figures to get your yardage. A 300 square foot stamped patio at 4 inches: 300 × 0.33 ÷ 27 = 3.67 cubic yards before overage. Order 4 yards.
Why Stamped Pours Need One Continuous Delivery
A second truck is a much bigger problem when you’re stamping concrete. By the time another load arrives, the first section may already be too far along to blend cleanly with fresh concrete. The color can shift, the surface can set at a different rate, and the stamping crew may have to stop or change pace to deal with the delay. That can leave visible differences between sections that are difficult to fix afterward.
For a stamped pour, take the extra time to get the yardage right before the first truck leaves the plant. Add some overage, double-check the order, and make sure the crew is ready to keep moving once the concrete starts arriving. Running short halfway through the pour is one of those mistakes that gets much harder to correct once the stamping has started.
Ready-Mix Delivery or Bagged Concrete?
The choice between a ready-mix truck and bagged concrete isn’t about preference. It’s about project size and logistics.
How Many Yards a Concrete Truck Holds
A standard ready-mix truck holds a maximum of 10 cubic yards. Most residential deliveries are between 2 and 8 yards. For very small projects, suppliers offer short-load deliveries at a premium.
Minimum Orders and Short-Load Fees
Most ready-mix suppliers have a minimum order, typically 1 cubic yard, and charge a short-load fee for orders below 3 to 5 yards, depending on the supplier. For very small projects under a yard, bagged concrete avoids that fee and gives the pourer full control over timing.
How Many Bags Equal One Yard
An 80-pound bag of concrete mix covers approximately 0.60 cubic feet. One cubic yard = 27 cubic feet. That’s 45 bags of 80-pound concrete per cubic yard.
| Option | Best Project Size | Cost | Labor | Finish Quality |
|---|---|---|---|---|
| Bagged concrete | Under 0.5 cubic yards | Higher per yard | Significant mixing labor | Suitable for small pours |
| Ready-mix truck | 1 cubic yard or more | Lower per yard at volume | Faster, less physical work | Consistent throughout pour |
For anything that involves stamped finishing, decorative color, or pattern work, bagged concrete isn’t practical regardless of project size. Stamped work requires a consistent, professionally proportioned mix delivered in quantity.
How Heavy Is a Yard of Concrete?
This weight matters for a few practical reasons. It determines whether a truck can fully load for a project on a tight or soft access route. It also informs how reinforcement and forming need to be designed, since wet concrete exerts significant pressure on forms before it begins to set.
A cubic yard of standard ready-mix concrete weighs approximately 3,900 to 4,050 pounds, or roughly two tons. The specific weight depends on the aggregate type, water content, and mix design. Lightweight mixes run lower, around 3,000 pounds per yard. Standard residential mixes fall consistently in the 3,900-pound range.
Common Mistakes When Estimating Concrete Yards
Most ordering errors trace back to a short list of avoidable mistakes.
- Measuring thickness at only one point when the subgrade is uneven, which produces an underestimate for the actual volume needed
- Forgetting to convert inches to feet before multiplying, which produces a yardage number that’s off by a factor of 12
- Skipping the overage addition and ordering exactly the calculated number, which almost always results in running short
- Ignoring thickened edges on driveways and slabs, which use more concrete than the average thickness calculation accounts for
- Using the same thickness assumption for different project types, such as applying a patio thickness to a driveway calculation
Double-checking the conversion step and adding overage before placing the order catches most of these errors before they become a delivery problem.
Concrete Yardage FAQs
How many yards does a 20×20 driveway take?
A 20×20 foot driveway at 5 inches thick: 20 × 20 × 0.42 = 168 cubic feet ÷ 27 = 6.2 cubic yards. Add 10 percent overage and order 7 yards.
Are online concrete calculators accurate enough to order from?
Online calculators are accurate for rectangular slabs when you input the correct numbers. The math they’re running is identical to the formula above. The limitation is that they can’t account for subgrade variation, form deflection, or any condition-specific factors that affect real-world usage. Use the calculator output as a base, then add your overage before placing the order.
Should I round up when ordering concrete by the yard?
Yes, always. Most ready-mix suppliers deliver in quarter-yard or half-yard increments above a minimum. Rounding down to avoid the cost of an extra quarter yard is a false economy when the alternative is a cold joint in the middle of a stamped driveway or an unfinished section waiting on a second truck.
Let Stamped Measure and Pour Your Next Project
Figuring yardage is one part of getting a concrete project right. The mix design, subgrade preparation, timing of the pour, and execution of the finish all determine how the slab performs over years of Fort Wayne winters. Stamped Concrete FW handles every stage from the initial measurement through the final seal, with transparent estimates that show exactly what’s included. Whether you’re planning a stamped concrete patio, a new driveway, or decorative flatwork for a commercial property, contact Stamped Concrete FW today for a free estimate.
