Concrete Mix Calculator
Calculate the quantities of cement, sand and coarse aggregate needed for a given volume of nominal mix concrete. Enter the wet concrete volume, or the length, width and thickness, and select a mix ratio to see the volume in m³, cu ft and cubic yards, the dry volume and the material breakdown in bags and cubic feet.
Concrete Mix Calculator
Nominal mixes are a site convention, not a design mix. Confirm the grade and water-cement ratio with a structural engineer and batching plant before placing concrete.
The volume one bag makes, printed on the bag (litres, or cu ft in imperial). Leave blank to skip.
- Cement
- 64 bags
- Sand
- 155.36 cft
- Coarse aggregate
- 310.73 cft
- Dry volume
- 15.400 m³
- 543.8 cu ft
- Concrete volume
- 10.000 m³
- 353.1 cu ft
- Concrete in cubic yards
- 13.08 yd³
- Premixed bags
- Add a bag yield to count bags
64 bags of cement, 155.4 cft sand and 310.7 cft aggregate for 10 m³ of 1:2:4 concrete.
How this was calculated
- Volume = length × width × thickness × pours (or the volume you enter)
- Cubic yards = volume ÷ 0.764555 m³
- Premixed bags = volume ÷ bag yield, rounded up
- Dry volume = wet volume × 1.54
- Cement bags = ROUNDUP(dry × cement/Σratio × 1440 / 50)
- Sand = dry × sand/Σratio × 35.31 cft
- Aggregate = dry × aggregate/Σratio × 35.31 cft
- Cubic yards = 10.000 m³ ÷ 0.764555 = 13.08 yd³
- Dry volume = 10.00 m³ × 1.54 = 15.400 m³
- Cement = ⌈ dry × cement/Σratio × 1440 / 50 ⌉ = 64 bags
- Sand = dry × sand/Σratio × 35.31 = 155.36 cft
- Aggregate = dry × aggregate/Σratio × 35.31 = 310.73 cft
How to use the concrete mix calculator
Enter the wet concrete volume (m³, cu ft or cu yd), or choose "Length × width × thickness" and enter the pour size and the number of identical pours. The volume is the volume of concrete as placed on site, including voids between particles. Select a nominal mix ratio from the dropdown: common options are 1:2:4 (M15), 1:1.5:3 (M20) and 1:1:2 (often quoted as M25). The calculator computes the dry volume (wet volume x 1.54), then derives cement bags, sand in cubic feet and coarse aggregate in cubic feet using the standard conversion factors.
How much concrete do I need?
Multiply length × width × thickness, in the same unit. A 3 m × 2 m slab 100 mm thick is 3 × 2 × 0.1 = 0.6 m³, which is 21.19 cu ft or 0.78 cubic yards (1 yd³ = 27 cu ft = 0.7646 m³). At 1:2:4 that needs 4 bags of cement, 9.32 cft of sand and 18.64 cft of aggregate.
In feet: a 10 × 10 ft patio 4 in thick is 10 × 10 × 4/12 = 33.33 cu ft, or 1.23 cubic yards (0.944 m³). For premixed bags, enter the yield printed on the bag: at 0.6 cu ft per bag that is 33.33 ÷ 0.6 = 55.6, so 56 bags; at 0.45 cu ft per bag, 75 bags. The bag count is rounded up and has no wastage added.
Understanding nominal mix ratios
A nominal mix is written as three numbers separated by colons, e.g. 1:2:4. These are the parts by volume of cement, sand and coarse aggregate respectively. The sum of the parts is used as the denominator when converting volume to bag count. A richer mix (smaller total) uses more cement per cubic metre. The 1:1:2 mix is the richest; it is often quoted as M25, but IS 456 allows nominal mixes only up to M20, so M25 and above need a design mix. The 1:4:8 mix is used for lean concrete under foundations.
Nominal mixes are a site convention, not a design mix. The actual grade achieved depends on the quality of materials, water-cement ratio, compaction and curing. For structural concrete, specify the grade (M20, M25, etc.) and have the batching plant confirm the mix design.
Conversions used
The calculator uses the following standard conversions: dry volume = wet volume x 1.54 (accounts for bulking of sand and voids in aggregate); cement density = 1440 kg/m3; one bag = 50 kg; 1 m3 = 35.3147 cft. These are approximate values used across India's construction estimating practice.
Next steps
Use the concrete mix output to prepare a Bill of Quantities for your project. Add approximately 5-10% extra for wastage. Order cement by the bag count shown above and aggregate by the cubic feet shown. For structural concrete, the steel reinforcement must be calculated separately: use the Steel Quantity Calculator or the Slab Concrete Calculator. Combine both with the India Construction Cost Estimator for a complete project cost estimate.
Frequently asked questions
How many cement bags for 1 m3 of concrete?
It depends on the mix ratio. For 1:2:4 (M15), about 6.3 bags per m3. For 1:1.5:3 (M20), about 8.1 bags. For 1:1:2, about 11.1 bags. The calculator rounds up to whole bags for your volume.
What is the difference between nominal mix and design mix?
A nominal mix uses fixed proportions by volume (e.g. 1:2:4) without testing. A design mix is developed from trial batches and specifies exact proportions by weight, with a target strength tested in a lab. Nominal mixes are suitable for small residential work. Design mixes are required for large or structural projects.
How much sand and aggregate for 10 m3 of concrete?
For a 1:2:4 mix: 10 m3 of wet concrete is 15.4 m3 dry (x 1.54), which needs about 155 cft of sand (15.4 x 2/7 x 35.31) and 311 cft of coarse aggregate (15.4 x 4/7 x 35.31), plus 64 bags of cement. Exact figures depend on the mix ratio selected. Use the calculator with your volume and mix to get precise numbers.
What is dry volume and why is it larger than wet volume?
Dry volume is the volume of the ingredients before water is added. It is larger than wet volume because sand bulks when it absorbs moisture (typically 20-35%) and there are air voids between aggregate particles. The standard factor of 1.54 accounts for this bulking and void space.
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