How to use the concrete calculator
- Choose a nominal ratio preset.
- Enter wet concrete volume in cubic metres or cubic feet, or select dimensions and enter length, width and depth in one unit.
- Select Calculate to see dry volume and the cement, sand and aggregate split.
- Review the fixed factors and project requirements before turning an estimate into an order.
Concrete calculator features
- Six nominal mix presets from 1:5:10 to 1:1:2.
- Direct volume and rectangular dimension input modes.
- Metric and imperial unit conversion.
- Dry volume, cement bag approximation, sand and aggregate volumes.
- Ratio chart with numerical results available without the chart library.
- Positive-input validation, keyboard focus indicators and mobile layout.
Worked concrete estimate: 1 cubic metre
Select the 1:2:4 preset and enter 1 m³. The 1.54 dry factor gives 1.54 m³ of dry materials: 0.22 m³ cement, 0.44 m³ sand and 0.88 m³ aggregate. The built-in bag-volume approximation gives about 6.34 cement bags. It does not add a waste allowance.
Concrete calculation questions
Does the selected grade guarantee concrete strength?
No. The historical grade labels identify ratio presets in this estimator. Concrete strength depends on an approved mix design, materials, water content, production and curing, which this tool does not evaluate.
What does the dry-volume factor mean?
The calculator multiplies wet volume by 1.54 as a fixed estimating allowance. It is an assumption of this tool, not a measurement of your actual materials. Confirm the appropriate approach for the project.
Can I change bag weight or cement density?
This version uses a fixed 1.226 ft³ bag-volume approximation. It has no bag-weight or density input. Do not interpret it as a configurable weight-based ordering model.
Does it include waste or costs?
No. Output covers nominal material quantities only. Waste, delivery, labour, taxes and prices are separate. Retain the unrounded estimate and decide purchase rounding with the supplier.
Example screenshot
The image shows a real browser calculation using the example above.
