Concrete Mix Design Calculator
7 bags cement (94 lb)
Plus 13.86 ft³ sand and 20.79 ft³ aggregate for 27 ft³ placed (dry factor 1.54).
- Volumetric batching by nominal ratio at 1:2:3 (cement:sand:aggregate) is field batching convention, not ACI 211 mix design. Strength-critical work needs a designed mix from your ready-mix producer.
- Dry-volume factor 1.54: loose dry ingredients compact to ~65% of their bulk volume when mixed and placed, a classic trade convention, labeled.
- One US cement bag = 94 lb ≈ 1 ft³ (definitional). Water is by workability/slump, not computed here.
Why This One Is Different
Looking for a simple bag-and-bucket ratio to mix your own concrete instead of a lab-grade mix design? This calculator converts your ratio to loose dry volumes using the classic 1.54 shrinkage factor and counts 94-lb cement bags, but it won't pretend to be a designed mix for anything strength-critical. Search for a "concrete mix design calculator" and what nearly everyone actually wants is a bag-and-bucket ratio like 1:2:3 cement to sand to aggregate by volume: nominal batching, the kind DIYers and small crews have used for generations. Real mix design is a lab process under ACI 211.1 that sets water-cement ratio, aggregate gradation, air content, and admixtures against a target strength and exposure class. This calculator does the former and says so plainly.
Where the Numbers Come From
- What this calculator does is volumetric nominal batching at a chosen ratio (1:2:3, 1:2:4, or 1:3:6), a long-standing field convention, not the same process as ACI 211.1 mix design. Source: ACI 211.1-91 (Reapproved), Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete
- Loose dry ingredients compact to roughly 65% of their bulk volume once mixed and placed, so this calculator multiplies target volume by 1.54 to get dry loose volume, a classic trade convention, labeled as such rather than a codified constant. Source: trade convention, labeled (construction-estimating canon)
- One US bag of portland cement weighs 94 lb and occupies almost exactly 1 cubic foot, a packaging convention the industry traces to a historic 1-cubic-foot barrel standard, used here to convert cement volume into a whole-bag count. Source: Portland Cement Association, bag-weight convention
- A fixed volumetric ratio can't promise you a strength or exposure class the way a real designed mix can: real mix design under ACI 211.1 sets water-cement ratio, aggregate gradation, air content, and admixture dosing against a specified compressive strength and exposure class, none of which a fixed ratio determines. Source: ACI 211.1-91 (Reapproved)
More Questions
Why does this calculator multiply my volume by 1.54?
Dry loose cement, sand, and aggregate compact down once mixed and placed, roughly to 65% of their loose bulk volume. The 1.54 factor converts your target finished volume back to the loose dry volume you need to batch.
Related Calculators
Formulas, waste factors, and cost models on this page follow the sourced conventions on our methodology page. Estimates only; verify with your supplier and local code.