Cement & Concrete Mix Calculator
Estimate cement, sand, gravel, water, bags, and material cost from a finished wet volume.
Mix inputs
Use decimal points and enter nonnegative values. The startup example represents 1 m³ of finished concrete.
Live estimate
Dry material volume breakdown
Material and cost breakdown
| Material | Volume | Mass / quantity | Unit price | Estimated cost |
|---|
How to use this cement calculator
What this calculator does
This calculator converts a required finished, or wet, concrete volume into estimated dry quantities of cement, sand, gravel, and mixing water. It also converts cement volume to kilograms, estimates the number of bags, and applies optional unit prices. It is useful for early budgeting, ordering, comparing nominal mix ratios, and checking whether a small project estimate is plausible. It is not a structural mix-design tool and does not certify compressive strength, durability, slump, air content, aggregate grading, admixture dosage, or code compliance. For those decisions, use an engineer-approved mix design or a ready-mix supplier.
When to use it
Use it when estimating materials for a small slab, footing, curb, post base, repair batch, or molded concrete item; when comparing bag demand across common nominal cement:sand:gravel ratios; when adding a realistic material allowance for handling loss; or when preparing a quick cost worksheet before asking suppliers for quotes.
How to calculate
- The calculator opens with a complete 1 m³ demonstration and a validated Excel workbook ready to download. Replace each sample value with your project data.
- Enter Wet volume, then review the Dry volume to wet volume ratio and Waste allowance. Select the required Concrete mix ratio.
- Confirm Cement density, Bag size, and Water-cement ratio. Add the three prices when a cost estimate is needed.
- Read the bag estimate, material volumes, water volume, chart, and breakdown table. Choose Download Excel to export the current validated state.
- Reset clears the demonstration values and results. Download Excel is then disabled until a complete valid state is entered again.
Input guide
Wet volume is required and accepts a positive decimal in cubic meters; for example, 1.25. Increasing it increases every material quantity proportionally. Do not enter dry ingredient volume here. Dry volume to wet volume ratio is required and typically falls around 1.52 – 1.57 for preliminary estimating; the startup value is 1.54. A larger factor increases all dry ingredients because it accounts for voids and volume reduction after mixing. Waste is a nonnegative percentage, such as 10, added after dry-volume conversion. Avoid adding the same allowance again when ordering.
Concrete mix ratio is required and represents cement:sand:gravel by volume. The 1:2:4 startup selection assigns one of seven total parts to cement, two to sand, and four to gravel. Richer mixes contain a larger cement share, but nominal ratios alone do not prove strength. The American Cement Association's applications guidance explains how cement paste, aggregate, and water combine in concrete.
Cement density is required in kg/m³; 1440 kg/m³ is a common loose bulk-density estimate for quantity calculations. Bulk density varies with packing and handling, so use supplier data when available. Bag size is required in kilograms; 50 kg is the example. Smaller bags increase the displayed bag count without changing cement mass. Water-cement ratio is required as a decimal mass ratio, such as 0.50, not 50. It multiplies cement mass to estimate water mass, with one kilogram of water treated as approximately one liter. The NRMCA guide to water-cementitious ratio limits explains why project specifications may cap this value.
Price of cement per bag, Price of sand per m³, and Price of gravel per m³ accept nonnegative U.S. dollar amounts. They are optional in concept but must contain valid numbers in this implementation; enter 0 when a component should be excluded from the cost total. Prices affect cost outputs only, not quantities.
Output guide
Bags of cement needed is the exact computed bag count and can be fractional; round up to whole purchasable bags when ordering. Cement weight is estimated from cement volume and bulk density. Cement volume, Sand volume, and Gravel volume are the allocated shares of total dry volume. Water volume is based on water-cement mass ratio, not on aggregate absorption or moisture correction. Total mix cost adds cement-bag cost and the two aggregate-volume costs. The header pills repeat the chosen mix, total dry volume, bag count, and estimated cost. The chart shows the three mutually exclusive dry-volume shares, while the table reports each material's volume, mass or quantity, unit price, and estimated cost.
Worked example
With 1.00 m³ wet volume, a 1.54 dry factor, and 10% waste, total dry volume is 1 × 1.54 × 1.10 = 1.694 m³. A 1:2:4 ratio has seven parts, so cement volume is 1.694 ÷ 7 = 0.2420 m³, sand is 0.4840 m³, and gravel is 0.9680 m³. At 1440 kg/m³, cement mass is 348.48 kg. Dividing by 50 kg per bag gives 6.97 bags. With a 0.50 water-cement ratio, water is 174.28 kg, or about 174.24 L. Using the startup prices gives a total estimated material cost of about $158.66.
Learn more
Cement is the binder, while concrete is the hardened composite of cement paste and aggregate; the American Cement Association's cement and concrete FAQ provides a concise distinction. To reduce unnecessary purchasing and disposal, see the U.S. EPA guidance on construction and demolition materials. Fresh concrete is highly alkaline, so review the cement industry's concrete handling safety guidance before mixing or placing material.