Estimating Concrete Requirements
Whether you're pouring a new driveway, setting fence posts, or building a patio, accurately calculating the volume of concrete required is essential to prevent delays or wasted material. Concrete in the US is universally ordered and measured in Cubic Yards (yd³).
The Golden Rule: Order 10% Extra
In construction, ground is rarely perfectly level, and forms can bow slightly. Always add a 5% to 10% spillage and waste margin to your exact calculation. Running out of concrete halfway through a pour creates a "cold joint" which can severely weaken the structure.
Bags vs. Ready-Mix Delivery
Should you buy bags from a hardware store or call a concrete truck?
- Under 1 Cubic YardBest to buy bags (approx. forty-five 60lb bags) and mix it yourself or rent a small mixer.
- Over 1 Cubic YardCall a Ready-Mix company for a truck delivery. It will save you immense manual labor and usually costs less per yard.
Pre-Mix Bag Yield Chart
If you are mixing your own concrete, use this table to understand the volume yield of standard pre-mixed concrete bags (like Quikrete or Sakrete).
| Bag Size | Volume Yield (Cubic Feet) | Bags Needed for 1 Cubic Yard |
|---|---|---|
| 40 lb. Bag | 0.30 ft³ | 90 bags |
| 50 lb. Bag (Fast Setting) | 0.375 ft³ | 72 bags |
| 60 lb. Bag | 0.45 ft³ | 60 bags |
| 80 lb. Bag | 0.60 ft³ | 45 bags |