Concrete Mix Ratio Calculator
Concrete is a mix of cement, sand and coarse aggregate in a fixed ratio, and getting the proportions right is what gives a pour its strength and workability. A common general-purpose mix is 1:2:4, meaning one part cement to two parts sand to four parts aggregate by volume. To estimate how much of each material you need, you split the total volume of concrete in proportion to those parts. This calculator takes the total volume of concrete and the three ratio numbers, then returns the volume of cement, sand and aggregate to two decimal places in the same volume unit you entered. It works for any whole or fractional ratio, so you can model a richer structural mix or a leaner foundation mix by changing the parts. Remember that dry materials occupy more space than the finished wet concrete because of voids, so many practitioners add an allowance, but this tool gives the clean proportional split of the volume you specify. Construction materials conventions and related standards are published by US federal agencies including the National Highway Traffic Safety Administration. Every figure is computed deterministically from the proportional split, shown below, with a worked example that reconciles exactly to the calculator so you can check each step yourself.
Each material is the total volume times its parts over the sum of parts. For a 1 m3 pour at a 1:2:4 ratio (7 parts total), you need 0.14 m3 cement, 0.29 m3 sand and 0.57 m3 aggregate.
Concrete mix ratio formula
Each = V x (parts / sum of parts)
V = total volume of concrete
sum = cement parts + sand parts + aggregate parts
cement = V c / sum, sand = V s / sum, aggregate = V a / sum
Add the three ratio numbers to get the total parts, then give each material its share of the total volume in proportion to its own parts. The three results always add back to the total volume you entered, since the shares are fractions of one whole.
Worked example
You need 1 m3 of concrete using a 1:2:4 mix (1 part cement, 2 parts sand, 4 parts aggregate).
- Add the parts: 1 + 2 + 4 = 7
- Cement: 1 x (1 / 7) = 0.1429 m3, rounded to 0.14
- Sand: 1 x (2 / 7) = 0.2857 m3, rounded to 0.29
- Aggregate: 1 x (4 / 7) = 0.5714 m3, rounded to 0.57
So a 1 m3 1:2:4 pour splits into about 0.14 m3 cement, 0.29 m3 sand and 0.57 m3 aggregate. These are the calculator's default inputs, so the results above match the widget exactly.
Common concrete mix ratios
Ratios are cement : sand : aggregate by volume. Richer mixes use more cement.
| Mix | Ratio | Typical use |
|---|---|---|
| General | 1 : 2 : 4 | Paths, non-structural |
| Standard | 1 : 1.5 : 3 | Footings, slabs |
| Structural | 1 : 1 : 2 | Beams, columns |
| Lean | 1 : 3 : 6 | Blinding, fill |
Mix conventions: US National Highway Traffic Safety Administration (NHTSA).
Concrete Mix Ratio Calculator: frequently asked questions
How do you work out a concrete mix ratio?
Add the ratio numbers to get the total parts, then give each material its share of the total volume. For a 1 m3 pour at 1:2:4 (7 parts), cement is 1/7, sand 2/7 and aggregate 4/7 of the volume, giving 0.14, 0.29 and 0.57 m3.
What does a 1:2:4 mix mean?
It means one part cement, two parts sand and four parts coarse aggregate, measured by volume. It is a common general-purpose mix. Richer mixes like 1:1:2 use proportionally more cement and are stronger; leaner mixes use less.
Do the material volumes add up to the concrete volume?
In this proportional split they sum exactly to the total volume you enter, because each share is a fraction of one whole. In practice dry materials occupy more space than the finished concrete due to voids, so many people add an allowance on top.
Can I use the same ratio for any unit?
Yes. The split is purely proportional, so if you enter the total in cubic meters the results are in cubic meters, and the same holds for cubic feet or any other volume unit.
What is the concrete mix split formula?
Each material equals the total volume times its parts divided by the sum of all parts.
Official sources
- Construction materials and engineering standards reference: US National Highway Traffic Safety Administration (NHTSA). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.