Calculate cement bags, sand, and gravel for any mix grade from M5 to M30. Volume helpers for slabs, columns, beams, and footings. African cement brand prices included.
Getting concrete quantities right is critical for any construction project. Too little cement means weak concrete that fails under load. Too much is wasteful and expensive. This calculator uses standard volumetric mix ratios from M5 through M30 — the grades most commonly used across African construction — to determine exact quantities of cement, sand, and aggregate for your project.
Concrete grades are classified by their characteristic compressive strength at 28 days, measured in N/mm² (Newtons per square millimetre). M15 (1:2:4) is the most widely used grade in African residential construction — suitable for floor slabs, strip foundations, and general structural work. M20 (1:1.5:3) is required for reinforced concrete (RCC) elements like suspended slabs, beams, and columns. M25 and above are used for high-rise buildings, bridges, and structures bearing heavy loads.
When cement, sand, and gravel are mixed with water, the resulting concrete volume is less than the sum of the individual dry materials. This is because the fine particles of cement and sand fill the voids between larger aggregate particles. The industry-standard factor is 1.54 — meaning you need 54% more dry material by volume than the final wet concrete volume. This calculator applies this factor automatically.
The water-cement ratio (W/C) directly affects concrete strength. A lower W/C ratio means stronger concrete but harder workability. For M15 concrete, a W/C ratio of 0.50 is standard. For M20, use 0.45. For M25, use 0.44. Too much water is the most common cause of weak concrete on African construction sites — workers often add extra water for easier pouring, but this dramatically reduces strength.
Concrete gains strength through hydration, which requires moisture. In the hot African sun, exposed concrete dries out quickly, halting the curing process and resulting in weak, cracked surfaces. Always cure concrete for a minimum of 7 days (14 days for structural elements). Cover with wet hessian sacks, plastic sheeting, or apply curing compound. Water curing in extreme heat (above 35°C) should be done 3-4 times daily. Failure to cure properly can reduce concrete strength by up to 40%.
Dangote Cement is Africa's largest manufacturer, producing 51 million tonnes per annum across plants in Nigeria, Ethiopia, Tanzania, South Africa, and other countries. BUA Cement and Lafarge Africa are major competitors in Nigeria. In East Africa, Bamburi Cement (part of Holcim) and ARM Cement dominate. PPC and AfriSam lead the South African market. Ghana is served by GHACEM and Diamond Cement. All produce standard Portland cement in 50kg bags — the universal unit of measurement on African construction sites.