What is quantity takeoff?

Quantity takeoffs (QTO) are precise estimates of the materials and labor costs required to finish a construction project. During the pre-construction phase, an estimator prepares them, breaking down the project into smaller, more manageable parts that are easier to evaluate. These measurements are used to prepare a construction scope bid. Estimators examine the drawings, specifications, and models to figure out different quantities and their costs. Since, the components, their quantity, and price are all included in the model, quantity take-off can be done automatically using Building Information Modelling (BIM). The time taken for completing a construction project can be reduced by the use of quantity takeoff. These takeoffs are also called material takeoffs and construction takeoffs.

The takeoffs are classified into two types depending on the method of preparing the quantity takeoff, they are digital takeoffs and manual takeoffs.

Manual takeoffs

This is a conventional quantity takeoff approach. Estimators examine the construction drawings and papers to see what the scope of work and specifications are. The estimator then uses the information in those documents to calculate the precise work measurements required to construct a structure. After going through the plans, the estimator then applies various formulas and computations to determine the precise number of each item by looking at the blueprints. After that, a value can be assigned to it to obtain a precise cost estimate. Because it is a complicated and time-consuming procedure, errors are bound to occur, leading to either overestimation or underestimation.

Digital takeoffs

Digital takeoffs are widely used in construction projects. Because of their accurate and quality cost estimate, digital takeoffs have high quality and are better than manual takeoffs. Digitizers, electronic devices acquire measurements from drawings and feed the data directly into computer programs. The scanned blueprint is uploaded into the software in a digital take-off. After that, the blueprint is examined to provide a detailed list of all materials required for the project. Wherever necessary, the cost estimator can make manual revisions. Construction takeoff softwares are also available which enables us to get more accurate results. Human error is greatly reduced as the formulas and equations are automated. Cloud-based technologies keep everything in one place and make it accessible to all teammates at any time. This protects data while simultaneously enhancing collaboration. Usage of such digital quantity takeoff services enables us to use and refer to previous quantity takeoffs for current and future projects. Digital takeoffs can be a complicated operation, necessitating the use of a skilled expert to effectively apply cost-based outcomes in software programs.  

Process of quantity takeoff

The process of quantity takeoff contains two stages, namely, the input and output stages. The input stage begins with accurate data being loaded onto blueprints or into the computer-assisted takeoff software. Then the relevant data is entered into the takeoff models to accomplish a high volume of takeoffs.

The output step transforms the concepts contained in the data into the project's requirements. At this point, having correct material estimations is also critical to obtaining accurate quantity takeoff solutions. This information is then utilized by contractors to submit construction bids and, the more precise the information, the more likely the proposals will be successful.

Flow chart showing the work flow of quantity takeoff in construction projects.

In the takeoff process, takeoff specialists or cost estimator uses the following formulas to locate and measure construction materials:

  • Unit count of items: The unit items such as doors, windows, light fixtures and pipe fixtures are calculated in this. The quantities of the items are multiplied by their unit price.
  • Linear: The lengths of the materials such as steel and piping are calculated in this. The cost of the items is then added in terms of cost per unit length.
  • 2D quantities: In this the two-dimensional quantities such as surface areas are calculated by multiplying the length with width to quantify the materials used for flooring tiles, roofing materials.
  • Volumetric quantities: The three-dimensional quantity such as volumes are calculated for earthworks and concrete works in a cubic meter.
  • Physical weight: The materials that are to be bought in terms of weight like steel are calculated in this.

Quantity takeoff softwares

Computer systems that assist users in deriving material quantity and estimations from digitally fed blueprint designs or BIM models are referred to as Quantity take-off software. Takeoff software includes tools for generating material and labor estimates. Most common blueprint file types, such as SVG, DXF, DWG, and even PDF or picture files, will be supported by the program. Estimators then use the estimate values obtained from the software to prepare the complete takeoff.

Some of the quantity takeoff softwares are Stack, Square takeoff, ProEst and Planswift.

Uses of quantity takeoffs

Quantity takeoffs help in preliminary project estimate, preparation of bill of quantity (BOQ) for contract documents, and also help to identify the number of resources required throughout the construction process. They are also used to estimate the material costs, to prepare an estimate to provide the payment bills to the contractor, to estimate construction costs, and to prepare the project schedule.

Context and Applications

The topic of quantity takeoff is an important aspect of preparing estimates for construction projects and also preparing contract documents in the bidding process. It is also used to estimate the amount payable to contractors. The significance of quantity takeoffs can be seen in the following engineering disciplines.

  • Bachelors in Civil Engineering
  • Masters in Civil Engineering
  • Masters in Construction Management

Practice Problems

1. Which of the following quantities are measured in a cubic meter?

  1. Earthwork excavation
  2. Damp proof course
  3. Woodworks
  4. None of the above

Answer: Option a

Explanation: Earthwork excavation is volumetric quantity and is usually measured in a cubic meter. The damp-proof course and woodworks are measured in square meters.

2. Which of the following are the uses of quantity takeoff in the construction industry?

  1. To provide payments to contractors
  2. To provide BOQ as a document for contracts
  3. To prepare accurate estimation of project costs
  4. All the above

Answer: Option d

Explanation: All the above options are the uses of quantity takeoff.

3. Which method of the following quantity takeoff is mostly used by the contractors and cost estimators?

  1. Manual takeoff
  2. Digital takeoff
  3. Both a and b
  4. None of the above

Answer: Option b

Explanation: Digital takeoffs are generally used as it provides more accurate takeoff solutions, whereas manual takeoff methods are bound to human errors.

4. Which of following items is estimated under the unit count method?

  1. Doors and windows
  2. Reinforced concrete
  3. Steel
  4. None of the above

Answer: Option a

Explanation: The quantity and cost of doors and windows are measured under unit count, while reinforced concrete is measured in cubic meters, and steel is measured in terms of kg (physical weight).

5. The process of preparing an estimate for project and labor costs is called-

  1. Quantity takeoff
  2. Preliminary estimate
  3. Rough estimate
  4. None of the above

Answer: Option a

Explanation: Quantity takeoff is also called quantity surveying. It is material-specific and calculates the cost and quantities of different materials used in the construction project. While the other two are methods of the estimation process.

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