Concrete Mix Ratios Explained
Mix ratios are shorthand for the proportions of cement, sand and aggregate. Here's what they actually mean and where each is used.
Reading the Numbers
A ratio like 1:2:4 means 1 part cement, 2 parts sand (fine aggregate) and 4 parts coarse aggregate, by volume. The smaller the total, the stronger the mix per part of cement.
Common Ratios Compared
| Mix | Cement:Sand:Aggregate | Typical Use |
|---|---|---|
| 1:2:3 | 1 cement, 2 sand, 3 stone | Lower strength; general fill, some slabs |
| 1:2:4 | 1 cement, 2 sand, 4 stone | Standard general-purpose concrete |
| 1:3:6 | 1 cement, 3 sand, 6 stone | Lean, low-strength; foundations on many sites |
Which to Use
Standard structural slabs and footings usually land around a 1:2:3 to 1:2:4 type mix. Heavier or thinner sections call for a stronger mix; always confirm against your structural spec and local practice.
Turn a Ratio Into Bags
Volumes are relative to a bag of cement. Translate the parts into cubic feet using a bag's yield, then multiply up for your slab volume — the concrete calculator does this for you.
Related Calculators
Disclaimer: Figures on this page are general reference information. Always verify exact requirements with your project specifications and a qualified professional.