An estimate for any construction work may be defined as the process of calculating the quantities and costs of the various items required in connection with the work. Before the start of any work for its execution, the owner of the builder should have a thorough knowledge of the volume of work. The minutest details can help him understand if the work can be completed within the stipulated time frame and budget. It also enables him to understand the probable cost that may be incurred to complete the proposed work. Therefore, it is necessary to list the probable costs or develop an estimate for the proposed work from its plans and specifications. An estimate is prepared by calculating the quantities from the drawings for various items and multiplying them with the unit cost of the item concerned.

 Purpose of Estimating:

To give a reasonably accurate idea of the cost.An estimate is necessary to give the owner a reasonably accurate idea of the cost to help him decide whether the work can be undertaken as proposed or needs to be curtailed or abandoned, depending upon the availability of funds and prospective direct and indirect benefits. For government works proper sanction has to be obtained for allocating the required amount.

Types of Construction Estimates:

  1.   Approximate Estimates: An approximate estimate is an approximate or rough estimate prepared to obtain an approximate cost in a short time. For certain purposes, the use of such methods is justified.
  2. Detailed Estimate: A detailed estimate of the cost of a project is prepared by determining the quantities and costs of everything that a contractor is required to provide and do for the satisfactory completion of the work. It is the best and most reliable form of estimate.

General Term in Estimation:


Takeoff is the process of counting, measuring, or otherwise extracting data from construction documents in order to quantify and cost it.


The extension is the process of calculating the takeoff items into meaningful financial data.


The breakdown is an analysis or separation of items in a particular component of an estimate.

Overhead cost

Overhead are the costs such as office rent, utility costs for the home office, project manager and estimator salaries, clerical staff, like payroll clerks and material handlers, are some of the common items that make up the overhead.

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