In construction, estimation is the process of forecasting the costs of building a structure. The estimating process may span several phases of a project, mirroring concept, schematic design, design development, and final construction documents. Estimation is typically handled by the general contractor. If you only know the cost of similar buildings, an analogous estimate is your best best in construction management. This technique works by taking past project costs and analogizing to your current project.

Estimation is a rough calculation of the actual value, number, or quantity for making calculations easier. Example: When taking a cab or waiting for a bill at a restaurant, we tend to estimate the amount to be paid. In short, it is an approximate answer. The process of determining the number of materials, resources, and especially project costs needed to operate during a construction project.