Purpose of construction estimating is to give a reasonably accurate idea of the cost.
Construction 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. Works are often let out on a lump sum basis, in which case the Estimator must be in a position to know exactly how much expenditure he is going to incur on them.
From the estimate of a work it is possible to determine what materials and in what quantities will be required for the work so that the arrangements to procure them can be made.
The number and kind of workers of different categories who will have to be employed to complete the work in the specified time can be found out from the estimate.
An estimate will help in determining amount and kind of equipment needed to complete the work.
The estimate of a work and the past experience enable one to estimate quite closely the length of time required to complete an item of work or the work as a whole. Whereas the importance of knowing the probable cost needs no emphasis, estimating materials, labor, plant and time is immensely useful in planning and execution of any work.