Concrete Calculator
Get accurate concrete estimates for your next project. Slabs, walls, columns, and stairs — all in one tool.
Last updated: January 2026
Concrete Calculator
How to calculate concrete
Concrete is measured in cubic yards. To calculate the volume: convert all dimensions to feet, multiply length × width × height for cubic feet, then divide by 27 (1 cubic yard = 27 cubic feet). For slabs, multiply length × width × (thickness in inches / 12) / 27.
Always order slightly more concrete than you need — 5-10% extra is standard to account for spillage, uneven subgrades, and waste. It's much cheaper to have a little extra than to run out and have to pay for a second partial load with delivery fees.
How many bags do you need?
A 60lb bag of concrete mix yields about 0.45 cubic feet. An 80lb bag yields about 0.6 cubic feet. This calculator shows how many bags of each size you would need for your project, along with the total cost if you're having it delivered by a ready-mix truck.