Concrete Calculator – How Much do I Need

A concrete calculator to know how much material you need for building a concrete element. Practical examples of concrete calculators to build:

  • Solid slab
  • Footing
  • Columns

Quantities of materials are given, such as cement, sand, gravel, steel, and water. Here you can know a lot of details about REBAR CALCULATOR AND SPACING FOR SLAB.

Concepts to Take Into account in Material Calculations to Build a Concrete Element

To build a traditional concrete slab (solid reinforced concrete slab) we need 5 basic materials:

MaterialsImperial UnitsMetric Units
Cement40 – 60 – 80 lbs bag25 kg

Additives are usually used in the preparation of concrete. Additives have the function of increasing the final resistance, and accelerating or retarding the setting of the concrete. We will not take them into account, so as not to complicate the calculations.

Concrete Calculator for Slabs

Concrete slab of 100 sqf.
Concrete slab of 100 sqf.

Volume and Material Concrete Calculator for Slabs

How much is a Bag of Cement

  • 20 bags of 50 kg of cement weigh 1 ton.
  • 40 bags of 25 kg of cement weigh 1 ton.
  • 55 bags of 40 pounds of cement weigh 1 ton.
  • 37 bags of 60 pounds of cement weigh 1 ton.
PoundsCubic Yards
40 pound bag0.011 cubic yards
60 pound bag0.017 cubic yards
80 pound bag0.022 cubic yards

Slab Thickness to Calculate How much Material do I need

It will be considered as standard slab thickness, 6 inches (150mm) , since this thickness or cant of concrete slab, allows greater constructive possibilities, which are detailed below…

  • It allows greater spans or separations between supports than a 4 or 5 inches (10 – 12 cm) thick slab.
  • It can have a greater amount of steel reinforcement (as necessary).
  • It allows to support higher loads (use and dead loads).
  • It achieves a better coverage of the reinforcement (rods), especially for areas with high relative humidity or constructions near the sea.
  • It is cheaper than a slab of 7 or 8” (15 – 20 cm) height.

In summary, a 6” high reinforced concrete slab has many benefits, since it is light, economical, it can take on a greater number of reinforcing rods , and therefore greater resistance, being useful for different types of constructions or homes. All this without the need to spend extra material.

Volume and Material Concrete Calculator for Footing

Volume and Material Concrete Calculator for Footing

Let’s see now, a material concrete calculator for columns, square and round.

Volume and Material Concrete Calculator for Columns

Volume and Material Concrete estimator for Columns

Waste to Calculate Materials for a Concrete Element

Economic technical indices for waste, widely accepted, are taken as references in the calculation of construction materials, which are detailed below.

Material% of Waste
Cement3 %
Sand8 %
Gravel7 %
Steel2 %
Water3 %

Type of Concrete to Use

There are different dosages that can be used to build a concrete slab. These (dosages) depend on many factors, including the materials used (raw material).

In the following examples we will do the material calculations for,

  • M20 (200kg/cm²) (20.0Mpa) concrete
  • M25 (250kg/cm²) (25.0Mpa) concrete

…since these are differents TYPES OF CONCRETE, most used in construction in most countries.

For the calculation of the amount of steel or reinforcing rods in the slab, a technical index of the construction is taken. A quantity range in kilograms is suggested.

It should be taken into account that concrete slabs may need a greater or lesser amount of reinforcement (slightly reinforced slabs or highly reinforced slabs), due to their support conditions (with or without walls or intermediate beams) and the loads they are going to support. (A roof is not the same as a mezzanine).

For the exact calculation of quantities of rods, a structural project must be available.

Since the diameter of the rods that you could use is not known, the quantity is given in kg.

Keep in mind that the 3/8″ (10mm) corrugated steel bar weighs 0.413lb/ft (0.62kg/ml). In the case of the 1/2″ (13mm) corrugated steel rod, it weighs 0.66lb/ft (0.99kg/ml).

In the markets, the reinforcing steel rods are sold in strips of 40ft (12ml) and 30ft (9ml).

For the mooring, you can use wire no. 18, at a rate of 7kg for every 1000kg of reinforcing steel.

So, let’s see the calculate of the amount of material that a slab carries.

How much Material do I need to Build a Slab of 100 ft²

How much material do I need for a slab of 10 square meters
Reinforced concrete slab of 10′×10”x6”.
For slab
of 100 ft² (9.3m²)
For 600 ft³ of
For 1.70m³ of
Cement41 bags of 40 lbs30 bags of 25kg
Sand1.41 yd³1.08 m3
Gravel1.73 yd³1.32 m3
Steel260 to 320 lbs120 to 145 kg
Water374 liters374 liters
Wire1.0 kg1.0 kg

For 250kg/cm² (25.0 MPa) of concrete

For slab
of 100 ft² (9.3m²)
600 ft³ of
1.70m³ of
Cement34 bags of 40 lbs24.5 bags of 25kg
Sand1.47 yd³1.12 m3
Gravel1.80 yd³1.38 m3
Steel240 to 300 lbs120 to 150 kg
Water340 liters340 liters
Wire1.0 kg1.0 kg

For 200kg/cm² (20.0 MPa) of concrete


You can leave your doubts and comments, about construction and BEAUTIFUL HOME DESIGN PLANS , which will be answered.

It may be interesting to see all these BEDROOM PLANS with measurements.

Later you will be able to know HOW MUCH MATERIAL YOU NEED TO BUILD A ROOM.

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