How Many Yards of Concrete Do I Need? Complete Yard Calculator Guide
Understanding Cubic Yards of Concrete
A cubic yard is the standard ordering unit for ready-mix concrete delivery. One cubic yard equals 27 cubic feet — picture a cube that’s 3 feet on each side. When you call a concrete supplier to order a truck, they’ll ask “how many yards?” This guide helps you calculate that number accurately.
The Concrete Calculator Yard Formula
Converting your project dimensions to cubic yards follows three steps:
- Calculate volume in cubic feet: Length (ft) × Width (ft) × Thickness or Depth (ft)
- Convert to cubic yards: Divide cubic feet by 27
- Add waste factor: Multiply by 1.05 to 1.15 (5–15% extra)
Quick Formula
Cubic Yards = (L × W × T÷12) ÷ 27 × (1 + waste%)
Where L and W are in feet, T is thickness in inches.
How Many Yards for Common Projects
| Project | Dimensions | Cubic Yards |
|---|---|---|
| 10×10 patio (4”) | 100 sq ft | 1.23 yd³ |
| 10×20 driveway (5”) | 200 sq ft | 3.09 yd³ |
| 20×20 garage (5”) | 400 sq ft | 6.17 yd³ |
| 24×24 garage (5”) | 576 sq ft | 8.89 yd³ |
| 30×40 shop (5”) | 1,200 sq ft | 18.52 yd³ |
| 4×50 sidewalk (4”) | 200 sq ft | 2.47 yd³ |
| 20 fence posts (10”×30”) | — | 1.01 yd³ |
| 4 deck footings (12”×42”) | — | 0.41 yd³ |
When to Order Ready-Mix vs Buy Bags
The crossover point where ready-mix truck delivery becomes more economical than bags is approximately 1 cubic yard (27 cubic feet). Here’s the comparison:
Cost per Cubic Yard
| Method | Cost per Yard | Labor Time | Notes |
|---|---|---|---|
| 60lb bags | $800–$900 | 6–8 hours mixing | 60 bags per yard |
| 80lb bags | $630–$750 | 4–6 hours mixing | 45 bags per yard |
| Ready-mix truck | $125–$175 | 10 min delivery | Minimum 1 yd usually |
| Short-load truck | $175–$275 | 10 min delivery | Under-minimum fee |
The math is clear: even with a short-load fee, truck delivery saves you hundreds of dollars in labor time for anything over 1 cubic yard.
Ordering Ready-Mix Concrete: What to Know
Minimum Order
Most ready-mix plants have a minimum order of 1 cubic yard. Below that, you’ll pay a “short-load fee” of $50–$100 on top of the per-yard price.
Ordering Extra
Always order 5–10% more than your calculation shows. Unlike bags where you can return extras, ready-mix that arrives is yours. But running short mid-pour is far worse than having a small amount left over. Pour leftover concrete into simple forms for stepping stones or post bases.
Delivery Logistics
- Truck needs access within 200 feet of the pour site (further requires a pump truck at $150–$300)
- Typical truck holds 8–10 cubic yards
- Pour rate is about 1 yard per minute from the chute
- Concrete starts setting in 60–90 minutes after mixing
- Weekday delivery is cheaper than Saturday; Sunday is often unavailable
Ready-Mix Specifications
When ordering, specify:
- Volume: Total cubic yards
- PSI strength: 3,000 PSI for slabs/patios, 4,000 PSI for driveways, 4,500 PSI for garage floors
- Slump: 4–5 inches for slabs (how fluid the mix is)
- Fiber or rebar: Let the supplier know if you want fiber mesh added
Concrete Calculator in Yards: Worked Examples
Example 1: Driveway Slab
A 12×30 foot driveway at 5 inches thick:
- Volume = 12 × 30 × (5÷12) = 150 cu ft
- In yards = 150 ÷ 27 = 5.56 cubic yards
- With 10% waste = 6.11 cubic yards
- Order: 6.5 yards (round up to nearest half-yard)
Example 2: Patio + Sidewalk Combined Pour
- Patio: 14×16 ft at 4” = 74.7 cu ft = 2.77 yd³
- Sidewalk: 4×20 ft at 4” = 26.7 cu ft = 0.99 yd³
- Combined = 3.76 yd³
- With 10% waste = 4.13 cubic yards
- Order: 4.5 yards
Example 3: Deck Footings (8 piers)
- 12” diameter sonotubes, 48” deep
- Each pier = π × (0.5)² × 4 = 3.14 cu ft
- 8 piers = 25.1 cu ft = 0.93 cubic yards
- With waste = 1.02 yards
- This is right at the minimum — bags might be more practical unless pouring with the footings as part of a larger project.
Tips for Calculating Yards Accurately
-
Measure twice — Re-check your form dimensions after building them. Forms can shift or bow.
-
Account for sub-grade — If your gravel base is uneven, your slab will use more concrete in the low spots. Add 5% extra.
-
Don’t forget depth variations — Garage floors often have a thicker edge (turn-down footing) that adds significant volume.
-
Use a concrete calculator — Manual math works, but our free concrete calculator handles unit conversions, waste factor, and multiple zones automatically. Enter dimensions once, get yards, bags, cost, and weight instantly.
-
Verify with your supplier — Call the ready-mix plant and tell them your project size. They’ll confirm your yardage estimate and can recommend PSI and slump.
Cost of Concrete Per Yard (2026 Prices)
National average pricing for ready-mix concrete:
- Standard mix (3,000 PSI): $125–$150/yd³
- High-strength (4,000 PSI): $140–$175/yd³
- Fiber-reinforced: $155–$190/yd³
- Saturday delivery: Add $50–$100 surcharge
- Pump truck: $150–$350 (if needed)
Total project cost = (yards × price per yard) + delivery fee + pump (if needed)
Calculate Your Concrete Now
Skip the manual math. Our free concrete calculator instantly shows your project volume in both cubic yards and cubic feet, with bag counts for when bags make more sense. Works for slabs, footings, post holes, walls, columns, stairs, and curbs — all in one tool.