How to Calculate the Amount of Concrete You Need

Whether you are pouring a new garage floor, building a set of stairs, or adding a commercial walkway, knowing exactly how much concrete you need will save time, money, and prevent costly project delays. Ordering too little can leave you scrambling for extra material, while ordering too much can mean wasted money and storage headaches.

Concrete volume is measured in cubic yards. To calculate it, you need three measurements: length, width, and thickness. Multiply these together to get cubic feet, then divide by 27 to convert to cubic yards.

Steps to calculate concrete needs
• Measure the length, width, and thickness of the area to be poured in feet (convert inches to feet for accuracy).
• Multiply length × width × thickness to find the cubic footage.
• Divide the cubic footage by 27 to get the total cubic yards.
• Add an extra 5–10% to account for waste, variations in the base, or over-excavation.

Example: For a garage floor measuring 20 feet by 24 feet with a thickness of 4 inches (0.33 feet), the calculation would be:
20 × 24 × 0.33 = 158.4 cubic feet ÷ 27 = about 5.9 cubic yards. You would round up to 6.5–7 cubic yards to ensure full coverage.

In residential projects, this method applies to garage floors, patios, or small driveways. For commercial work, it’s equally important for loading docks, warehouse floors, or entranceways where larger volumes are needed and reinforcement may increase thickness.

Choosing the right mix for your climate and use case is just as important as ordering the right volume. In colder regions with freeze-thaw cycles, opt for mixes designed for durability to protect against cracking and scaling.