LOC is the most common way of quantifying software size; however, this cannot be done until the coding process is complete. Function points have the advantage of being measurable during the design phase of the development process or possibly earlier.

J. Albrecht proposed a metric for software size and the effort required for development that can be determined early in the development process. This approach computes the total function points (FP) value for the project, by totaling the number of external user inputs, inquiries, outputs, and master files, and then applying the following weights: inputs (4), outputs (5), inquiries (4), and master files (10). Each FP contributor can be adjusted within a range of ±35% for a specific project complexity.