Software Sizing

Use international standard techniques to quantify your software

Total Metrics are recognised world leaders in the area of Functional Size Measurement (FSM). Our consultants have been developers and/or reviewers for all the ISO certified FSM Methods, including IFPUG Function Points and COSMIC FFP Function Points. We were the project editors and ISO convenor for the ISO / IEC Standards 14143 for Functional Size Measurement. Our consultants are certified in both IFPUG and COSMIC function points and bring over 15 years of experience to their function point counting.

How can you size software?

Software can be quantified based on an international standard of assessing the functionality it delivers and the complexity of that functionality. This methodology enables any type of software to be quantified in internationally recognized units of size. This then allows comparisons to other software applications or development projects to benchmark quality and productivity. For a planned project we use size to estimate development effort pr for implemented applications we use size to assess effort to support and enhance the software. The activity of measuring functional size is known as 'function point counting'.

Total Metrics use specialized SCOPE to record and report the details of the function point count. SCOPE:

  • models your software's functionality to leave you with a fully quantified map of your application or project
  • uses a 'functional decomposition' to model your Project or Application. This functional model provides the 'map' on which to identify the logical processes/transactions
  • provides a facility which enables individual transactions to be assigned attributes with User customised key words, e.g. Specifications 'Complete' and 'Deficient'. Reports can then be produced selectively listing and sizing functions functions that have been flagged with the attribute. This is a useful tool for negotiating scope changes with suppliers and customers
  • allows a function point count to be calculated from any position on the hierarchy, thus enabling relative sizes of functional areas to be measured, e.g. compare the functional size of the business area
  • allows a project to be re-sized at any phase during the life cycle, facilitating project tracking. The sizing provides an 'audit' trail of the project for cost variation discussions based on quantitive data reflecting the true size of the changes and when and why they occured
  • allows automatic update of the baseline function point count and subsequent enhancement counts of the application over its life time

The level of accuracy and the quantity of documentation for a function point count can be tailored to the purpose for which the count will be used. See Total Metrics Articles : Levels of Function Point Counting. The quicker the count the more cost effective the sizing activity for the client.


Deliverables from a function point count of each project or application include:

  • a fully documented function point count including all assumptions, provided to you as a PDF or softcopy. The softcopy database will enable easy maintenance over the life of the application to reflect future scope changes. SCOPE Viewer™ is downloadable for free and can be used to view all details of the count.
  • a functional hierarchy decomposed to elementary process level. Each elementary process classified into function type (input/output/enquiry)
  • a functional Hierarhcy of Logical Files (RETs and DETs) classified by type (Internal Logical and External Interface files)
  • a list of Logical Files (Data Groups) and Elementary Processes (transactions), their complexities and position on the functional hierarchy
    • Total Metrics produces a brief 'Analysis Report' for the application in addition to the detailed Count Results Report. The Function Point Count Analysis Report will outline the strategy for the count, application boundary, identify issues, noteworthy aspects of this type of development, summarize results, make comparisons to industry based data (ISBSG) and make recommendations.

Total Metrics' Functional Sizing brochure

The Total Metrics consulting charge for our functional size measurement is determined by:

  • the size and complexity of the software
  • the quality of the documentation supporting the software
  • which additional estimation and productivity evaluation activities are required