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Foundation Cement Calculator

Calculate cement, sand, and aggregate volumes for Strip, Slab, or Footing foundations. Includes dry volume conversion and mix ratio presets.

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Total Usage 1 times
Category Foundation & Concrete
Wet Volume (Target)0.00 m3
Dry Volume (Required)0.00 m3
Cement Required0 kg0 Bags (50kg)
Sand Required0.00 m3
Aggregate Required0.00 m3
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About

Accurate material estimation prevents expensive onsite shortages or wasteful surpluses. In foundation work, the distinction between wet volume (geometry) and dry volume (material procurement) is often overlooked by novices. Concrete shrinks by approximately 54% when water is added; therefore, a dry volume safety factor of 1.54 is mathematically required to fill a specific geometric form.

This tool addresses the geometry of three common foundation types: Strip (continuous), Slab (area), and Footing (isolated). It applies the specific density of cement (1440 kg/m3) and standard mix ratios (M20, M25) to derive exact bag counts. Engineers use these values to order logistics, ensuring structural integrity without overspending on binding agents.

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Formulas

The calculation proceeds in three stages: Geometric Volume, Dry Volume conversion, and Material Fractioning.

1. Geometric Volume (Vwet):

{
L × W × D for Strip/SlabL × W × D × Count for Footings

2. Dry Volume (Vdry):

Vdry = Vwet × 1.54

3. Cement Mass (Mc):

Vdry × Ratiocement × ρcementRatiototal

Reference Data

GradeMix Ratio (C:S:A)Compressive Strength (28 Days)Cement (kg/m3)Typical Use
M51:5:105 MPa140PCC, Bedding
M7.51:4:87.5 MPa170Foundations (Light)
M101:3:610 MPa220Leveling Course
M151:2:415 MPa300General Flooring
M201:1.5:320 MPa400Reinforced Structures
M251:1:225 MPa550Heavy Load Foundations
M30Design Mix30 MPaVariableHigh-Rise Columns
M35Design Mix35 MPaVariablePiles, Piers

Frequently Asked Questions

Dry materials (cement, sand, aggregate) contain air voids. When water is added, these voids collapse, reducing the total volume. To get 1 cubic meter of wet concrete, you physically need 1.54 cubic meters of dry ingredients. Ignoring this leads to a 35% material shortage.
No. Reinforcement (rebar) estimation requires structural load analysis and bending schedules. This tool strictly calculates the volumetric matrix (cement, sand, aggregate).
The global standard is often 50kg per bag. However, some regions use 42kg or 94lb bags. This calculator outputs "Total Mass" first to allow you to divide by your local bag size.
Not necessarily. M20 is a standard for general reinforced concrete, but heavy load-bearing structures or marine environments may require M25 or higher. Always check the structural engineer's drawings.