How to Calculate Concrete for Foundations

Published on January 18, 2026

Calculating concrete for a foundation is slightly more complex than a simple slab because you are often dealing with different shapes, such as footings and vertical walls.

Step 1: Calculate the Footings

Footings are the horizontal base that supports the foundation walls. To calculate the volume, treat the footing as a long, narrow slab. Measure the total linear length of the perimeter, the width of the footing, and the depth.

Step 2: Calculate the Walls

For foundation walls, you use the same logic: Length x Height x Thickness. Ensure you are consistent with your units (e.g., convert everything to feet before multiplying).

Professional Estimation Tip

For complex foundations with multiple steps or varying depths, break the project down into smaller rectangular sections and calculate each one individually using our online concrete calculator. Sum the results at the end and add a 15% waste factor for foundation work, as the ground for footings is often rough and uneven.