How Do You Calculate Concrete Yardage? | Concrete Yardage | Concrete Yardage
Published on 2026-05-30
How Do You Calculate Concrete Yardage? The Complete 2026 Guide
If you are planning a concrete project - whether it is a patio, driveway, shed base, or garage floor - the first question is always the same: how do you calculate concrete yardage? Ordering too little means a weak cold joint mid-pour. Ordering too much means wasted money. This guide walks you through the exact formula, waste factors, and real-world pricing so you can order with confidence.
The Concrete Yardage Formula (Step by Step)
The formula is simple, but getting each step right matters:
- Measure your dimensions in feet. Length × Width gives you square footage.
- Convert thickness to feet. Divide inches by 12. For a standard 4-inch slab: 4 ÷ 12 = 0.33 ft.
- Calculate cubic feet. Length × Width × Thickness (in feet) = cubic feet.
- Convert to cubic yards. Divide cubic feet by 27 (since 1 cubic yard = 27 cubic feet).
- Add a waste factor. Multiply by 1.10 for standard slabs, 1.15 for irregular shapes.
Quick Example: 10×10 Patio at 4 Inches Thick
| Step | Calculation | Result |
|---|---|---|
| Square footage | 10 ft × 10 ft | 100 sq ft |
| Thickness in feet | 4 in ÷ 12 | 0.33 ft |
| Cubic feet | 100 × 0.33 | 33.3 cu ft |
| Cubic yards | 33.3 ÷ 27 | 1.23 yd³ |
| With 10% waste | 1.23 × 1.10 | 1.36 yd³ |
Order 1.5 cubic yards from your supplier. Always round up to the nearest 0.25 or 0.5 yard - most ready-mix companies sell in quarter-yard increments.
Common Thicknesses by Project Type
| Project | Recommended Thickness | Why |
|---|---|---|
| Patio / Sidewalk | 4 inches | Light pedestrian and furniture loads |
| Driveway (cars only) | 5 inches | Supports passenger vehicles up to 6,000 lbs |
| Driveway (trucks / RVs) | 6 inches | Handles heavier axle loads without cracking |
| Shed Base | 4 inches | Sufficient for garden sheds under 400 sq ft |
| Garage Floor | 6 inches | Supports vehicle weight plus stored equipment |
| Commercial Slab | 8 inches | Designed for forklifts and heavy equipment |
What About Irregular Shapes?
Not every slab is a perfect rectangle. For L-shaped patios, circular pads, or angled driveways:
- L-shapes: Break into two rectangles, calculate each separately, then add.
- Circles: Area = π × radius². Then apply the same thickness conversion.
- Triangles: Area = ½ × base × height.
- Trapezoids: Ave
For complex shapes, add 15% waste instead of 10% - you will lose more concrete to over-excavation and form irregularities.
Bags vs. Ready-Mix: When Makes Sense?
The yardage calculation also helps you decide between bagged concrete and a ready-mix truck:
| Project Size | Cubic Yards | Best Option | Why |
|---|---|---|---|
| Under 1.5 yd³ | Small patio, walkway, fence post | Bags | Truck minimums start at 3-10 yd³ + short-load fees |
| 1.5 – 10 yd³ | Standard driveway, garage floor | Ready-mix | Cheaper per yard, faster pour, consistent mix |
| Over 10 yd³ | Large driveway, commercial slab | Ready-mix | Bags become logistically impossible (100+ bags) |
Bag math: One 80-lb bag yields 0.60 cubic feet. One 60-lb bag yields 0.45 cubic feet. Multiply your total cubic feet (with waste) by the appropriate yield to get bag count.
2026 Concrete Pricing by Region
After calculating yardage, the next piece of the puzzle is cost. Here is what ready-mix concrete costs per cubic yard in 2026:
| Region | Price per yd³ | Notes |
|---|---|---|
| Northeast | $185 – $215 | Short-load fees common under 5 yd³ |
| Southeast | $145 – $165 | Most competitive pricing nationally |
| Midwest | $150 – $175 | Freeze-thaw additives may add $10-15/yd³ |
| Southwest | $135 – $160 | Dry climate = fewer weather delays |
| West Coast | $195 – $225 | Highest material costs + environmental fees |
| Mountain | $160 – $185 | Limited supplier options in rural areas |
These are base material prices. Add $100–$400+ for short-load fees (if under minimum), Saturday delivery surcharges, and fuel surcharges in remote areas.
Common Mistakes When Calculating Concrete Yardage
Even experienced DIYers make these errors. Avoid them:
- Skipping the waste factor. Always add 10-15%. Running short means a second delivery costing $150+ in short-load fees.
- Measuring thickness in inches without converting. Dividing by 12 is the step most people forget. 4 inches ≠ 4 feet.
- Ordering exact, not rounding up. If the math says 2.1 yards, order 2.5. Suppliers do not sell 0.1-yard increments.
- Ignoring subgrade variability. If your excavation depth varies by 2 inches across the slab, your actual yardage will be higher than the formula predicts.
- Confusing square yards with cubic yards. Square yards measure area. Cubic yards measure volume. They are not interchangeable.
FAQ
How many cubic yards do I need for a 20×20 driveway?
A 20×20 slab at 5 inches thick = 200 sq ft × 0.417 ft = 83.3 cu ft ÷ 27 = 3.09 yd³ + 10% waste = 3.4 yd³. Order 3.5 cubic yards.
Can I calculate yardage for a circular pond border?
Yes. Measure the outer radius and inner radius. Area = π × (R² - r²). Then multiply by thickness in feet and divide by 27.
How accurate is the 10% waste factor?
10% is reliable for flat, rectangular slabs on well-compacted subgrade. Increase to 15% for sloped ground, irregular shapes, or if your forms are not perfectly straight.
Should I include rebar or mesh volume in my calculation?
No. The volume displaced by rebar or wire mesh is negligible - less than 0.1% of total volume. Do not subtract it.
Calculate Your Concrete Yardage in Seconds
Enter your project dimensions into our free concrete calculator and get instant cubic yardage, bag counts, regional pricing, and a complete order summary - no pencil and paper needed.
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