# 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. If you want to know more details about HOW MANY RODS ARE NEEDED TO BUILD A SLAB, you should also check this link.

We start…

## Concepts to take into account in Material Calculations to Build a Concrete Element

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

There are other materials (additives) that are usually used in the preparation of concrete.

The additives have the function of maximizing the basic materials, increasing the final resistance, and accelerating or retarding the setting of the concrete. Now, we will not take them into account, so as not to complicate the calculations.

### How much is a Bag of Cement

It is taken as a reference that 55 packages or 55 pounds bags of cement weigh one ton. Besides, 40 packages or 25 kg bags of cement weigh one ton. Besides:

• 40 pound bag yields .011 cubic yards
• 60 pound bag yields .017 cubic yards
• 80 pound bag yields .022 cubic yards

## Concrete Calculator for Slabs

### 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 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

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

## Volume and Material Concrete Calculator 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.

### 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 the 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

For 250kg/cm² (25.0 MPa) of concrete

For 200kg/cm² (20.0 MPa) of concrete

It may also be useful to know HOW MANY RODS ARE IN A TON OF STEEL and how to calculate it.