Software Sizing

Software Sizing

Frequently Asked Questions About Software Sizing

Software is everywhere in modern life - from automobiles, airplanes, utilities, banks, to complex systems and global communications networks. They run the gamut from tiny applets that comprise just a handful of instructions to giant systems running millions of lines of code that take years to build.

Software professionals are at the front lines of this information revolution.  This post addresses Frequently Asked Questions about measuring the size of software applications after they’re finished and estimating the work for a project that has yet to be started. We hope it will help software professionals do a better job of describing what they are building for their companies as software continues to grow in strategic importance to our companies and to our daily lives.

Question:  What do we mean by the term, “Software Size”

Answer:  For starters, think of T-shirts – Small, Medium, Large, or Extra-Large, or houses that can range from a small summer cottage all the way up to a 20,000 sq ft Hollywood mansion on a sprawling estate.

So it goes with software. You can have a small program with a few cool features, or a huge, complex computerized trading system for the New York Stock Exchange comprised of millions of lines of code, and everything in-between.

Question:  I have a large project and its size is 20 people. Is that what you mean?

Answer:  Not quite. That’s actually the number of the people on your team, or number of staff resources on the project.  It’s not the amount of functionality, or the volume of software created by a team of that size. 

Question:  Ok, so you’re saying that small feature sets for a software program - or a long list of features - is what you mean by the size of the software. Do you also mean lines of code?

Code Counters and Size Measurement

Regardless of which size measures (Effective SLOC, function points, objects, modules, etc.) your organization uses to measure software size, code counters provide a fast and easy way to measure developed functionality. If your organization uses Effective (new and modified) SLOC, the output from an automated code counter can generally be used "as is". If you use more abstract size measures (function points or requirements, for example), code counts can be used to calculated gearing factors such as average SLOC/FP or SLOC/requirement.

The QSM Code Counters page has been updated and extended to include both updated version information and additional code counters. Though QSM neither endorses nor recommends the use of any particular code counting tool, we hope the code counter page will be a useful resource that supports both size estimation and the collection of historical data.

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Benchmarking Software Sizing Estimation