EngineerHub.orgHow to use this calculator
Enter the finished concrete volume and the selected nominal mix ratio. Adjust bag size and water-cement ratio only when appropriate.
Inputs
Results
Background
Engineering basis, equations, assumptions, interpretation and practical limitations for this calculator.
Nominal volume ratios are a site-estimating method, not a performance mix design. Moisture, grading, aggregate density, admixtures and required strength alter actual quantities.
Do not use a generic ratio for structural or durability-critical concrete unless permitted by the project specification. Water should be adjusted for aggregate moisture and workability controls.
Frequently Asked Questions
Practical questions about assumptions, inputs, interpretation and limitations.
It means one part cement, two parts sand and four parts coarse aggregate by loose volume. It is a nominal proportion, not a guaranteed strength class.
Loose cement, sand and aggregate contain voids and rearrange during mixing and compaction. A dry-volume factor is therefore used to estimate the larger bulk volume of ingredients required for a given finished concrete volume.
No. Strength also depends on cement type, aggregate grading, water-cement ratio, admixtures, batching accuracy, compaction and curing. Structural concrete should use an approved mix design where required.
Water-cement ratio strongly influences workability, porosity and potential strength. Adding water beyond the intended mix can reduce strength and durability even if placement becomes easier.
For purchasing, cement bags normally need to be rounded up to whole bags and adjusted for waste. The calculator provides an estimate; actual batching should follow the approved mix and site procedures.