Backlog sizing essentials

Software backlog sizing and estimation are often considered wasteful and time-consuming. Estimates are also more than occasionally misused, yet reliable estimates are essential for sound investment decisions and effective planning.

ScopeMaster automatically provides a standardised functional interpretation and functional size estimate based on the text of each user story.

backlog sizing starts with the functional interpretation of each user story

Why automated sizing > team Sizing

Not only does ScopeMaster provide a reasonable size estimate for the backlog, but it can do so instantly and effortlessly, and even size backlog items that might be missing!

Knowing the size leads to more sophisticated management decision making and planning about projects
Software Backlog Sizing Automated by ScopeMaster

Estimating software backlog size (and subsequently cost and schedule) is important to give managers an understanding of how much it will cost and how long it will take. Managers and executives are constantly faced with difficult decisions about software work. On larger projects, budgets and schedules are frequently exceeded, both of which lead to considerable waste and inefficiencies. Managers need to know the likely cost and duration to develop software so that they can plan accordingly. They are expected to make dependable decisions about priority and staff allocation and yet often do so without reliable software estimation of the time and effort needed.

Most software professionals believe that it is impossible to estimate software development work, or that it will always be very time consuming, which simply isn’t true.

Why are developer estimates unreliable?

Developers often struggle with estimation. Estimation with techniques such as story points or T-shirt sizing is really just a proxy for approximating (as in guessing) hours or even days of work. Teams might often argue otherwise, but this is likely an attempt to obfuscate in order to promote. When developers provide estimates for a piece of work, they may deliberately understate the work to “win” the work and protect their work. They may also overestimate to avoid work that they don’t want to do.

Once developers have provided a manager with an estimate of a user story, a Sprintly of work or even an entire backlog, the manager might then use that estimate as a target, a measure of control or even a commitment, all of which are unsuitable uses of an estimate.

Unfortunately, developers almost always underestimate the time and effort actually required for software delivery. It is human nature to do so. They only consider known factors, but with software, there are often unknowns that cause delay. Theses are rarely permitted in technical estimation for this reason.

So how do we estimate backlogs more reliably?

Tens of factors can affect the time and effort to develop software (such as complexity, work environment, executive support, technical experience, requirements volatility). The single most significant factor in determining effort or cost is size, specifically functional size. Once you know the functional size, you can quickly derive valid estimates for other dimensions, such as:

  • staffing
  • develop time
  • costs
  • tests needed to achieve suitable quality
  • …and much, much more

What is functional size?

Functional size arises from Functional Size Measurement (FSM). It is a mature and proven standardised technique for software sizing, a formal engineering practice approved by ISO standards groups, and agnostic of technology, coding and development methodology. As universal measure that applies to all types of software, it is considered from the user’s perspective. Above all else, functional size is objective and valid, and consistent—in other words, two people measuring the functional size should come up with the same number each time. The unit of measure is the function point; to put it more specifically, it is the COSMIC function point (or CFP), which can be estimated or counted solely and precisely from requirements and specifications. FSM has been around for many years and has proven to be the most reliable measure of software size, allowing you to estimate or measure size before, during and after the coding process.

ScopeMaster is the first and only tool to reliably estimate functional size directly and automatically from a backlog of written requirements. Don’t just take our word for it, though; experts and academics around the world agree that ScopeMaster is a breakthrough automated sizing tool.

Bring certainty to your software work with automated functional size measurement.

For more on COSMIC functional size measurement, visit https://www.cosmic-sizing.org.

Automated software estimation with ScopeMaster

Fast: About 10 times faster than a sizing expert.

Precise: Within 15% of a manual sizing.

Standards-based: Results in the leading ISO standards for software sizing.

Three leading standards automated:

ScopeMaster was conceived as a tool to automate the clerical work of measuring the functional size of software from requirements. In the words of our founder, Colin Hammond, “The reason I set out to write a tool to do this is because, as a software project manager, I found that functional size is the single most significant factor that I need in order to manage a project successfully.”

ScopeMaster interprets the functional intent of the user story or software requirement, and thus is able to automate functional sizing, which can then be used for further estimation of software development.

Not only is ScopeMaster much faster than measuring manually, it costs substantially less than manual sizing. Certified counters are scarce, and ScopeMaster takes much of the drudgery out of doing the job. ScopeMaster “reads” the requirements, interprets the functional intent and then sizes them accordingly. It can estimate size at about three CFP per second. You could size a 1,000 CFP set of requirements (about $1m of outsourced software) in about two or three minutes. You might then review the results to correct any requirements mistakes and verify the functional size of each requirement. Once verified by the analyst, the estimate becomes an exact measurement, which can then be used for fixed price outsourcing of software development work.

COSMIC functional sizing

Over the years, several variations of functional size metric have been created. Only five have achieved ISO recognition (COSMIC, IFPUG, Mark II, NESMA and FiSMA). IFPUG, Mark II, NESMA and FiSMA are all similar in that they are derived from the original ruleset created by Allan Albrecht at IBM back in the 1980s. The COSMIC functional size methodology evolved from earlier methodologies, specifically designed to address their shortcomings. The key advantages that make COSMIC sizing methodology more relevant to modern software are:

  1. It is based on software principles, dealing elegantly with interconnected software layers and software architectures.
  2. Estimates and measurements can be made before all requirements are known, highly suited to Agile development.
  3. It has been automated and thus takes negligible learning.

Story points are prevalent across all Agile projects; they are a team-specific proxy measure for effort. Each team has a common understanding of the magnitude of a story point—typically in the order of a few hours of effort—although there are no strict rules. Story points are not a universal currency; they are not a standard and cannot be reliably used to compare teams or projects. Story points are a useful internal indicator of anticipated effort when no other means of estimation are available. Function points, however, are universal, standard, and highly applicable to Agile development as much as any other development methodology. Click here to read more on the merits of CFP vs Story Points.

Size is the cornerstone of software estimation

Once you know the functional size in COSMIC function points (CFP), you can quickly establish other metrics that are directly related to size, such as cost, effort and schedule. After the size in CFP is established, you can then use industry conversion values that map function points to these metrics. Rather than use industry conversions, you can use your own historical project data to establish your own velocity benchmarks.

Agile estimation

Instead of burning time by discussing story points or playing with Fibonacci cards, we feel that Agile estimation is ideally achieved via functional sizing with COSMIC FP. That means you can better estimate:

  • Velocity (average CFPs delivered per week)
  • Schedule (number of weeks needed to deliver)
  • Cost (total cost to design, develop, test and deliver)
  • Effort (effort needed to design, develop, test and deliver)
  • Quality (defect potentials for each constituent of the delivery)

How fast can you derive estimates?

Manually, a competent analyst can measure function points at a rate of several hundred FPs per day (which translates to software worth hundreds of thousands of dollars), although it depends on the quality and clarity of the requirements and specifications. The speed also depends on the experience and ability of the analyst. With ScopeMaster, you can expect to achieve these rules about four times faster.

Automated Estimation in COSMIC Function Points

Estimating as you write user stories in Jira

Using the ScopeMaster Story Analyser for Jira, you can estimate your stories’ functional size without even leaving Jira. The text of your user story is analysed by ScopeMaster’s powerful language engine to detect the functional intent and functional size.

Size is not the only factor that determines software costs and schedule, but it is the most significant one. Discover the value and insight from automated functional sizing through our brochure:



For those who consider estimation to be harmful, unimportant or just too difficult, check out Steve McConnell’s excellent article on why estimation is an important and valuable skill that project managers need.

Problems with story points and T-shirts

  • Inconsistent
  • Gameable
  • Nonlinear

Story points are a team-based opinion about the amount of effort it might take to build software from a developer’s perspective. Story points are essentially a proxy for effort estimates, e.g. one story point might be the equivalent of one ideal employee working for one ideal day. They are highly subjective and dependent on the opinions of the team. Additionally, they vary from team to team, and even within the same team over time. Their inconsistency and gameability renders them impractical as a reliable engineering metric.