Cement Calculator — Bags, Sand & Aggregate for Concrete
Enter the volume of concrete you need and the mix grade to find out exactly how many 50 kg cement bags, how much sand and how much aggregate to order.
m³
Concrete grade / mix ratio
403,2 kg · 0,28 m³
1:1.5:3
mix ratioCement
18.2%
Sand
27.3%
Aggregate
54.5%
- 1
Dry volume (+ settlement factor)
1 × 1.54 = 1,54Dry ingredients need ~54% more volume than finished wet concrete. - 2
Cement volume
(1 ÷ 5,5) × 1,54 = 0,28 m³ - 3
Cement weight
0,28 m³ × 1,440 kg/m³ = 403,2 kg - 4
Bags needed (50 kg each)
⌈403,2 ÷ 50⌉ = 9
Как работи този калкулатор?
Multiply your wet concrete volume by 1.54 to get the dry volume, then split by mix ratio (e.g. 1:1.5:3 for M20). Cement (m³) = (1/5.5) × dry volume; cement weight = volume × 1440 kg/m³; divide by 50 and round up for bags. Add 5–10% waste allowance when ordering.
Формула
How this is calculated
Concrete is a mixture of cement, sand (fine aggregate) and coarse aggregate combined with water. The mix ratio — written as cement:sand:aggregate — defines the relative volumes of each dry ingredient. Common structural grades range from M10 (1:3:6, lower strength) to M25 (1:1:2, higher strength), where M stands for mix and the number is the 28-day compressive strength in MPa.
The calculation starts with the wet volume of concrete you need (length × width × thickness). Because dry materials settle and compact when mixed with water, they occupy about 54% more volume in dry form than the finished concrete. Multiplying the wet volume by 1.54 gives the dry volume. Each material's share is then found by dividing its ratio parts by the total parts and multiplying by the dry volume: cement volume = (1 / total_parts) × dry volume. Cement weight is then density × volume, using the standard bulk density of Ordinary Portland Cement (OPC) of 1,440 kg/m³, and dividing by the standard 50 kg bag weight gives the bag count, rounded up.
The calculation assumes all materials are measured by volume, OPC cement is used, and a 5–10% waste allowance is not built in — add extra bags for spillage, uneven formwork or wastage. For water-to-cement ratio, site conditions (temperature, slump) and admixtures, consult a structural engineer. This tool is for estimating material quantities before purchasing; exact batching should follow IS 10262 (India), BS 5328 (UK), ASTM C94 (US) or the applicable local standard.
Често задавани въпроси
When dry cement, sand and aggregate are mixed together and compacted with water, they fill void spaces and settle, reducing the total volume to about 65% of the original dry volume (or equivalently, you need 1.54× more dry material to get a given wet concrete volume). The 1.54 factor is an industry-accepted empirical constant for this settlement.
For M20 (1:1.5:3 mix), roughly 8 bags of 50 kg cement are required per cubic metre of wet concrete. This equals about 400 kg of cement, 0.44 m³ of sand and 0.88 m³ of coarse aggregate per m³ of concrete.
Yes — add 5–10% to the calculated quantities to cover spillage, uneven formwork surfaces, mixing loss and over-excavation. For large pours, 5% extra is usually sufficient; for complex shapes or manual mixing, allow 10%.
Известен също като
TG we-Calculate Editorial Team. (2026). Cement Calculator — Bags, Sand & Aggregate for Concrete [Online calculator]. TG we-Calculate. https://we-calculate.com/bg/calculator/cement-calculator
TG we-Calculate Editorial Team. "Cement Calculator — Bags, Sand & Aggregate for Concrete." TG we-Calculate. 2026. https://we-calculate.com/bg/calculator/cement-calculator.
TG we-Calculate Editorial Team, "Cement Calculator — Bags, Sand & Aggregate for Concrete," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/bg/calculator/cement-calculator
@misc{wecalculate_cement_calculator, title = {Cement Calculator — Bags, Sand & Aggregate for Concrete}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/bg/calculator/cement-calculator}}, year = {2026}, note = {TG we-Calculate} }
Помогна ли ви този калкулатор?