Cement Mix Ratio Calculator
Work out exactly how much cement, sand, and aggregate you need for your concrete pour. Enter your volume and mix ratio to get bags of cement, material weights, and dry volume in seconds.
Concrete Volume & Mix Ratio
Enter the volume of concrete you need and your chosen mix ratio
Total finished (wet) volume of concrete required, in cubic metres.
Extra material to allow for spillage and mixing losses.
Choose a common grade, or select “Custom ratio” to enter your own.
Standard cement bags are typically 50kg (or 25kg in some regions).
Kilograms of water per kilogram of cement, typically 0.4–0.6.
Materials Required
Cement, sand, aggregate and water for your pour
Enter your concrete volume and mix ratio, then click Calculate Materials Needed to see your cement bags, sand, and aggregate quantities.
Common Concrete Mix Ratios
Standard cement, sand, and aggregate ratios by concrete grade, and their typical use on site.
| Grade | Mix Ratio | Cement per m³ | Typical Use |
|---|---|---|---|
| M5 | 1 : 5 : 10 | ~3 bags | Lean mix, blinding layers |
| M7.5 | 1 : 4 : 8 | ~4 bags | Mass concrete, mud slabs |
| M10 | 1 : 3 : 6 | ~5 bags | Footings, levelling course |
| M15 | 1 : 2 : 4 | ~6–7 bags | General purpose slabs & footings |
| M20 | 1 : 1.5 : 3 | ~8 bags | Structural slabs, driveways |
| M25 | 1 : 1 : 2 | ~11 bags | Columns, beams, RCC work |
Cement Mix Ratio FAQ
Everything you need to know about mix ratios, dry volume, and estimating materials for a concrete pour.
A cement mix ratio describes the proportion of cement, sand, and coarse aggregate used in a concrete mix, written as Cement:Sand:Aggregate. For example, a 1:2:4 ratio means 1 part cement, 2 parts sand, and 4 parts aggregate by volume. The ratio determines the strength grade of the finished concrete.
When cement, sand, and aggregate are mixed with water, the volume shrinks because the dry materials fill the voids between each other. To get 1 cubic metre of finished wet concrete, you need roughly 1.54 cubic metres of combined dry materials. This factor accounts for that volume loss and bulking.
For a common 1:2:4 mix, roughly 6 to 7 bags of 50kg cement are needed per cubic metre of finished concrete. This changes with the mix ratio: richer mixes like 1:1.5:3 need more cement per cubic metre, while leaner mixes like 1:4:8 need fewer bags.
Lean mixes like 1:4:8 or 1:3:6 are typically used for mass concrete, footings, and blinding layers. A 1:2:4 mix is a common general-purpose ratio for slabs and non-structural work. Richer mixes such as 1:1.5:3 or 1:1:2 are used for structural elements like columns and beams that need higher strength. Always check local building codes or a structural engineer’s specification for load-bearing work.
Water quantity is usually expressed as a water-cement ratio, commonly between 0.4 and 0.6 by weight of cement. A ratio of 0.5 means 0.5kg of water for every 1kg of cement. Too much water weakens the concrete, while too little makes it hard to work with, so follow the ratio suited to your cement type and site conditions.
Yes, it’s standard practice to add a wastage or safety margin of around 5 percent to account for spillage, over-excavation, uneven surfaces, and mixing losses on site. Larger or more complex pours may need a higher margin.
Yes, mix ratios and this calculator assume dry, loose volumes of sand and aggregate. Damp sand can bulk up in volume by 20 to 30 percent, so if your sand is wet or damp, you may need to increase the measured volume slightly to get the correct dry quantity.
This calculator uses standard reference densities of 1440 kg per cubic metre for cement, 1600 kg per cubic metre for sand, and 1500 kg per cubic metre for coarse aggregate. Actual site densities can vary slightly depending on material source and moisture content.