Work out cement, sand, aggregate and water quantities from a concrete mix ratio, plus mortar mix ratio — metric or imperial.
Cement : Sand : Aggregate, by volume.
Typical range: 0.4-0.6 for general concrete work.
| Item | Value |
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Choose a common mix ratio preset (like 1:2:4) on the Concrete Mix Ratio tab, or enter your own cement:sand:aggregate ratio. Enter the wet concrete volume you need, a water-cement ratio, and your cement bag size. For mortar instead of concrete, switch to the Mortar Mix Ratio tab and use a type preset or custom cement:sand ratio. Use the Cost tab with your local material prices for a material cost estimate.
A concrete mix ratio expresses the proportion of cement, sand and coarse aggregate by volume — for example, 1:2:4 means 1 part cement to 2 parts sand to 4 parts aggregate. This is different from calculating the total volume of concrete needed for a slab or footing (which our Cement Calculator handles) — a mix ratio calculation instead answers "given this ratio and this target volume, how much of each ingredient do I need?"
Dry, loose cement, sand and aggregate have air gaps between their particles. When mixed with water and compacted, these gaps get filled in, so the finished wet concrete volume is less than the dry material volume you started with. This calculator uses a commonly cited factor of 1.54× to convert your target wet volume into the dry material volume needed, then splits that dry volume according to your ratio:
Each material's volume is then converted to weight using standard reference bulk densities (cement ≈ 1,440 kg/m³, sand ≈ 1,600 kg/m³, aggregate ≈ 1,550 kg/m³), and cement weight is divided by your bag size to get the number of bags, rounded up.
| Ratio (C:S:A) | Typical use | Approx. grade |
|---|---|---|
| 1 : 1.5 : 3 | Structural elements, higher strength | ~M20 |
| 1 : 2 : 4 | General purpose slabs, footings | ~M15 |
| 1 : 3 : 6 | Lean mix, non-structural fill | ~M10 |
| 1 : 4 : 8 | Mass concrete, blinding layers | ~M7.5 |
These are commonly cited nominal mix ratios used for general estimating, not a substitute for an engineered mix design. Actual grade designations (M15, M20, etc.) are typically based on design mix calculations that account for specific aggregate properties and target strength testing, not a fixed nominal ratio alone.
The water-cement ratio is the weight of water divided by the weight of cement in the mix. A lower ratio generally produces stronger, less porous concrete, but a mix that's too dry is difficult to work with and compact properly. A ratio of 0.4 to 0.6 is typical for general concrete work — this calculator multiplies your chosen ratio by the calculated cement weight to estimate water quantity.
Mortar is used to bond masonry units like brick and block, and uses a simpler cement:sand ratio without coarse aggregate. Type M (about 1:2) is a high-strength mix used for below-grade or load-bearing work; Type S (about 1:2.5) suits general structural masonry; Type N (about 1:3) is a common general-purpose mix for above-grade work; and Type O (about 1:4) is a low-strength mix for non-structural or restoration work. These are simplified cement:sand ratios — actual ASTM C270 mortar types also specify lime content and can be proportioned or tested by property, so check your project's specification for structural masonry work.
The Cost tab multiplies your cement bag count by a price per bag, and sand/aggregate weight (converted to tonnes or tons) by a price per tonne/ton. This is a material-only estimate — delivery, admixtures, waste and labour aren't included. Material prices vary by region and supplier, so use your local current quote for an accurate total.
For 1 m³ of concrete at a 1:2:4 ratio with a 0.5 water-cement ratio and 50kg bags: dry volume = 1 × 1.54 = 1.54 m³. Total parts = 7, so cement volume = 1.54 × (1/7) = 0.22 m³, sand = 0.44 m³, aggregate = 0.88 m³. Cement weight = 0.22 × 1,440 = 316.8 kg, which needs 7 bags of 50kg cement (rounded up from 6.34). Water = 316.8 × 0.5 = 158.4 litres.
A frequent mistake is using the wet (finished) volume directly as the dry material volume, which understates how much cement, sand and aggregate to actually buy — the 1.54× dry volume factor accounts for this. Another is confusing a concrete mix ratio (which includes coarse aggregate) with a mortar mix ratio (cement and sand only) — these serve different purposes and aren't interchangeable. Finally, treating a nominal ratio like 1:2:4 as equivalent to a specific engineered grade (like M20) can be inaccurate, since real mix design accounts for aggregate size, moisture content and target strength testing that a nominal ratio alone doesn't capture.
This calculator uses commonly cited nominal mix ratios and standard reference bulk densities for general estimating — it is not an engineered mix design. It does not account for specific aggregate gradation, moisture content, admixtures, or target compressive strength testing. For structural, safety-critical, or code-compliant concrete work, use a mix design provided by a qualified concrete supplier, testing laboratory or engineer. Mortar type presets are simplified cement:sand ratios and do not include lime content specified in ASTM C270 mortar types.
A concrete mix ratio expresses the proportion of cement, sand and coarse aggregate by volume, such as 1:2:4 (1 part cement, 2 parts sand, 4 parts aggregate). Different ratios produce different strength concrete - richer mixes (more cement relative to sand/aggregate) are generally stronger.
M20 concrete is commonly associated with a nominal mix ratio of approximately 1:1.5:3 (cement:sand:aggregate), though actual mix design for M20 is typically based on design calculations rather than a fixed nominal ratio - check your project's specification.
A 1:2:4 ratio is a commonly used general-purpose/medium-strength mix, often used for slabs, footings and general structural work. Use the calculator above with this ratio and your target volume to get exact material quantities.
The water-cement ratio is the weight of water divided by the weight of cement in a mix, commonly 0.4 to 0.6 for general concrete work. Enter your chosen ratio in the calculator above and it multiplies this by the calculated cement weight to give the water quantity.
This depends on your mix ratio, target volume and bag size. Enter these into the calculator above and it works out the cement weight from the ratio, then divides by your bag size and rounds up to whole bags.
Mortar mix ratio is typically expressed as cement:sand, commonly ranging from about 1:2 (Type M, high strength) to 1:3 (Type N, general purpose). Use the Mortar Mix Ratio tab above with a type preset or your own custom ratio.
Concrete mix ratio includes coarse aggregate (cement:sand:aggregate) and is used for structural elements like slabs and footings, while mortar mix ratio is just cement and sand (sometimes with lime), used for bonding masonry units like brick or block.
Dry, loose materials (cement, sand, aggregate) have air gaps between particles that get filled in and compacted when mixed with water, so the dry volume needed is greater than the finished wet concrete volume - commonly estimated using a factor of about 1.54.
A richer mix with more cement relative to sand and aggregate, such as 1:1.5:3, generally produces higher-strength concrete than a leaner mix like 1:3:6. Actual strength also depends on water-cement ratio, aggregate quality and curing - for structural work, use an engineer-specified mix design.
No - it uses commonly cited nominal mix ratios and reference material densities for general estimating, not a full engineered mix design that accounts for specific aggregate properties, admixtures or target strength testing. For structural or safety-critical work, use a qualified mix design from a concrete supplier or engineer.
Water quantity is based on your chosen water-cement ratio multiplied by the calculated cement weight - commonly a water-cement ratio of 0.4 to 0.6 is used for general concrete work. Enter your ratio in the calculator above for an estimated water volume.