Concrete & Cement Mix Calculator
Calculate total concrete volume in $\text{m}^3$ and exact quantities of cement bags, sand, gravel, and water for slabs, beams, and footings.
What does the Concrete Calculator do and how to use it?
The Herramix Concrete & Cement Mix Calculator helps civil engineers, contractors, architects, and builders estimate concrete volume ($\text{m}^3$) and exact material quantities (Portland cement, washed sand, crushed gravel, and mixing water) for slabs, footings, columns, and retaining walls.
Enter your element dimensions in meters (length, width, and thickness/height), choose the target compressive strength (from $2000\text{ PSI}$ lean concrete up to $3500\text{ PSI}$ structural concrete), select your local cement bag weight ($50\text{ kg}$, $42.5\text{ kg}$ / $94\text{ lb}$, or $25\text{ kg}$), and include a waste percentage.
Usage example
Scenario: Pouring a $5\text{ m} \times 4\text{ m}$ concrete slab with a thickness of $0.15\text{ m}$ ($15\text{ cm}$) using a $3000\text{ PSI}$ ($1:2:3$) structural mix and $5\%$ waste allowance.
Result: Net volume $3.00\text{ m}^3$ ($3.15\text{ m}^3$ with waste) · 22.1 bags of 50 kg cement ($1103\text{ kg}$) · $1.76\text{ m}^3$ of sand · $2.65\text{ m}^3$ of gravel · $567\text{ L}$ of water.
Frequently Asked Questions
How many bags of cement are needed per cubic meter ($\text{m}^3$) of concrete?
For a standard $3000\text{ PSI}$ ($21\text{ MPa}$, $1:2:3$ ratio) structural mix, you need approximately $350\text{ kg}$ of cement per $\text{m}^3$, which equals 7 bags of 50 kg (or 14 bags of 25 kg).
What does a 1:2:3 concrete mix ratio mean?
It indicates the loose volume proportion of dry materials: 1 part cement, 2 parts sand (fine aggregate), and 3 parts gravel (coarse aggregate).
Why do the loose volumes of sand and gravel add up to more than 1 $\text{m}^3$?
Dry loose aggregates contain air voids between particles. When mixed with cement paste and water, fine sand grains fill the voids between coarse gravel stones, compacting into $1\text{ m}^3$ of dense wet concrete.