RCC Slab Calculator
Calculate cement, sand, aggregate, and steel rebar required for a Reinforced Cement Concrete slab.
Slab Details (Metric)
Material Estimation
Calculating RCC Slab Materials
Reinforced Cement Concrete (RCC) refers to concrete containing steel rebars for tensile strength. Calculating materials for an RCC slab involves two distinct phases: finding the concrete material weights (cement, sand, aggregate), and calculating the steel reinforcement weight.
The concrete volume is found by multiplying Length × Width × Thickness. Because dry materials shrink by 54% when water is added, you must multiply this wet volume by 1.54 to find your dry volume. You then divide this dry volume according to your mix ratio (e.g., M20 is 1:1.5:3). The steel is calculated as a percentage of the wet volume (typically 1%) multiplied by the density of steel (7850 kg/m³).
Standard Concrete Grades (Mix Ratios)
M15 (1 : 2 : 4)
1 part cement, 2 parts sand, 4 parts aggregate. Used for general non-structural groundwork and leveling.
M20 (1 : 1.5 : 3)
The industry standard for residential RCC slabs, beams, and columns.
M25 (1 : 1 : 2)
High-strength mix used for commercial load-bearing structures and foundations.
Frequently Asked Questions
How much steel is required for an RCC slab?
As a general rule of thumb in civil engineering, steel reinforcement in a standard residential RCC roof slab constitutes about 0.7% to 1.0% of the total concrete volume.
What is the best concrete grade for an RCC slab?
M20 grade concrete (1 part cement : 1.5 parts sand : 3 parts aggregate) is the widely accepted minimum standard for RCC slabs in residential construction. Heavy-duty commercial slabs may require M25.
Why do we multiply concrete volume by 1.54?
Dry concrete materials (cement, sand, and gravel) contain voids filled with air. When water is added, the mix compresses and shrinks by roughly 54%. Therefore, to get 1 cubic meter of wet concrete, you must start with 1.54 cubic meters of dry materials.
How thick should an RCC roof slab be?
A typical residential RCC roof slab is usually 125mm to 150mm (5 to 6 inches) thick depending on the span between supports.