To calculate quantity in construction various methods and technologies are being used to generate accurate results. Whatever the methods are being used, the most important concern is that the output must be spot-on. So, in the end, the contractors and project managers do not need to face budget overruns. Whether it is about estimating residential, commercial, or industrial projects! In short, understanding how to calculate quantities helps avoid unnecessary wastage and financial losses.
Qualified and efficient cost estimators know the exact ways how to count the overall materials that are the base of evaluating the overall cost. Various experienced companies are working in the US market to offer precise quantity takeoff services to contractors. One of the top firms is Bidding Estimate who have expert estimators to count materials.
In this article, first, we will discuss the significance of the calculation of quantities in the construction job. After that, we will jump into the methods about how to calculate materials quantity.
Importance of Accuracy in Quantity Calculation
Accuracy is considered a serious and essential element while calculating material quantities in construction.
Let us show you why.
The first reason is the cost control in which a minor calculation error can derail the whole construction project. Suppose if you end up over or underestimating, how would you cover the project delays and higher costs?
Second, the most important thing is to prevent wastage of materials. If you know the exact amount of quantity for your construction work, you can save your budget easily.
By precisely knowing the required quantities, contractors can plan the procurement and construction schedule more efficiently.
With your accurate estimates or takeoffs, your clients are more than satisfied with your job. You will get more portable projects and grow your business.
Now, let’s see which are the construction materials that need to be precisely calculated!
- Concrete
- Bricks or Blocks
- Steel Reinforcement
- Cement
- Sand
- Gravel or Coarse Aggregates
- Tiles
- Pain
- Timber
- Labour and more!
Methods to Calculate Quantity in Construction
First of all, you need to know about proper formulas to calculate quantities to avoid Common Mistakes in the Construction Cost Estimating process.
Follow our steps and roughly estimate the quantities for your construction project:
1. Concrete Calculation
The following formula calculates concrete in cubic meters (m³).
Concrete Volume (m³) = Length (m) × Width (m) × Height (m)
Let’s take an example you are constructing a concrete slab of 5 meters long, 4 meters wide, and 0.2 meters thick.
Calculation:
Concrete Volume = 5 × 4× 0.2 = 4 m³
Concrete Volume=5×4×0.2=4m³
You will need 4m³ concrete for the slab.
2. Brick Calculation
Bricks are calculated on the number of units required per square meter. The formula used for brick calculation is:
Number of Bricks = Area of Wall (m²)/Area of One Brick (m²)
Let’s say a wall is 3 meters high and 10 meters long, and the size of one brick is 0.19 meters long and 0.09 meters wide.
You will calculate it like this:
Wall Area =3×10=30m²
Area of One Brick=0.19×0.09=0.0171 m²
Number of Bricks=30/0.0171=1,754 bricks
This is how you can calculate the number of bricks for your construction project.
3. Steel Reinforcement Calculation
Steel reinforcement calculation is dependent on the length, diameter, and number of bars needed for the structure.
The following formula is used to calculate steel reinforcement:
Weight of Steel (kg)=𝑑2×𝐿×𝑁/162
Let’s assume 10 bars of 12mm diameter steel, each 6 meters long:
Weight of Steel=12(Square) ×6×10/162
=144×6×10/162
= 53.33 kg
4. Cement, Sand, and Aggregate for Concrete
Concrete mix typically follows a ratio of materials such as 1:2:4 (cement: sand) for general concrete construction.
Example for M15 Concrete: For 1 cubic meter of M15 grade concrete (1:2:4):
Cement
Cement Volume=1/(1+2+4)× Total Volume of Concrete
=1/7 × 1= 0.143m³
Convert this to bags of cement:
Cement Bags= 0.143m³/0.035m³ per bag
= 4.09 bags are needed
Sand
Sand Volume=2/7×1
=0.286m³
Aggregate
Aggregate Volume=4/7×1
=0.571m³
The results that are calculated represent the required materials to prepare 1 cubic meter.
5. Tile Calculation
Tile is calculated in square meters and the formula that helps to evaluate the total number of tiles is:
Number of Tiles=Floor/Wall Area (m²)/Area of One Tile (m²)
Suppose you need to calculate a 12 square meters floor area, using tiles that are 0.3 meters by 0.3 meters:
Tile Area=0.3×0.3=0.09 m²
Number of Tiles=12/0.09=133tiles
You are going to need 133 tiles for your space!
Final Words
In short, these are a few formulas based on which you can calculate quantity in construction. Remember, the most crucial thing is to be accurate in the whole process. However, advanced methods also involve the usage of the latest software and tools. Contractors can avoid mistakes in calculations by using the above formulas. Whether calculating concrete, bricks, steel reinforcement, or paint. In addition to that, never forget to add extra funds in the overall estimations or takeoffs to prevent overbudgeting. This way you set the successful foundation of your construction projects.
