Concrete Volume Calculator
Accurate volume estimation prevents costly over-orders and project-delaying short pours. This calculator converts project dimensions into cubic yards and estimates ready-mix truck loads.
Project Dimensions
Ready-mix trucks typically carry 8–10 cubic yards. Short loads (under 4–5 yards) may incur surcharges. Actual needs vary with subgrade conditions and form accuracy.
Understanding Concrete Volume
Concrete is sold by the cubic yard. One cubic yard equals 27 cubic feet — enough to pour a 4-inch slab covering 81 square feet. The formula:
Volume (yd³) = Length (ft) × Width (ft) × Thickness (ft) ÷ 27
Always convert thickness from inches to feet first (divide by 12). A 4-inch slab is 0.333 feet thick.
Common Slab Thicknesses
| Application | Typical Thickness | PSI Strength |
|---|---|---|
| Sidewalk / Patio | 4 inches | 3,000–3,500 |
| Residential Driveway | 4–6 inches | 3,500–4,000 |
| Commercial Slab | 5–6 inches | 4,000–5,000 |
| Garage Floor | 4–6 inches | 3,500–4,500 |
| Foundation Footing | 8–12 inches | 3,000–4,000 |
Ready-Mix Ordering
Ready-mix concrete is delivered in trucks holding 8–10 cubic yards. Key ordering terms:
- Short load fee: Many plants charge $40–60 per yard under their minimum (typically 3–5 yd³)
- Overtime/waiting: Most drivers allow 5–7 minutes per yard for unloading; excess time is charged
- Slump: 4–5 inch slump is standard for flatwork; higher slump is easier to pour but weaker
- Fiber mesh: $5–8 per yard; replaces or supplements wire mesh reinforcement
Frequently Asked Questions
How much does a cubic yard of concrete weigh?
Standard concrete weighs approximately 3,900–4,050 pounds (about 2 tons) per cubic yard. Lightweight aggregate mixes weigh 2,800–3,200 pounds per yard.
How many bags of concrete make a cubic yard?
It takes approximately 45 bags of 80-pound premix (such as Quikrete) to make one cubic yard. For anything over 1–2 cubic yards, ready-mix delivery is more practical and cost-effective.
Should I order extra concrete?
Yes. Industry standard is 10% over-order for most projects. Running short mid-pour creates a cold joint that weakens the slab. It is always better to pour slightly more than slightly less.