In general, the accuracy of a cost estimate will reflect the information available at the time of the estimate.
The cost of construction constitutes only a fraction, but a substantial fraction, of the total cost of the project. However, it is the part of the cost under the control of the construction project manager.
This tool provides the calculations with the required accuracy levels of construction cost estimates that vary in different stages of project development, ranging from Ball Park figures in the first stage to fairly reliable figures for the control of Budget before construction.
Since design decisions taken in the initial phase of the life cycle of a project are more provisional than those made at a later stage, it is expected that the cost estimates made in the previous stage will be less precise. In general, the accuracy of a cost estimate will reflect the information available at the time of the estimate. However for early stages, this tool provides default values that greatly facilitate calculations.