Story Points

What they mean & how we use them

So you may be thinking:

What are Story Points?

Story points rate the complexity of a task, relative to the complexity of other tasks.

Video explanation!

So they're hours?
Nope! Story points rate complexity, not time. A task might take me longer to build than you, but we can probably agree that it is more or less complicated than another task.
Give me an example.
I can't tell you how much a motorcycle or a pickup or an airplane weighs, but I can tell you that a motorcycle weighs less than an airplane, and a pickup is somewhere in the middle.
How does this help?
Over time, a team's average velocity will reveal about how much complexity they can build in a given time. This helps predict how long a backlog will take to build. Building on the example, stakeholders can decide if they want five motorcycles or one airplane this sprint.
Sounds stupid. Why not hours?
Estimating is never perfect, but hours have a tendency to vary wildly while waiting for follow-up meetings, getting clarifications, variance between developers' skills, etc. But over time, a project team has a tendency toward a predictable velocity of building complexity.
How do we pick a size?
Debate with teammates about how a story might be completed, you might know a shortcut and someone else may anticipate a pitfall. Compare against other stories on complexity and approach, not by debating hours. “Does this sound as hard as that 8-pointer from last sprint or does it sound more like a 5-pointer we just talked about?”
How do we standardize?
As a company with many teams, if we can all come to a somewhat common understanding of rating complexity, estimates become portable and our gained business intelligence can be shared across teams.
What about “shirt sizes?”
Nothing wrong with that, but S + L isn't mathematically useful the same way 3 + 13 is. Story point values are 1, 2, 3, 5, 8, 13, and 20. Your product owner probably translated your shirt sizes into these numbers.

Here's a guideline:

General themes of the kinds of stories we've assigned to point values, pulled from Jira. Lacking context makes this difficult to envision but if you have any better ideas, open a PR!

Not pictured, but acceptable: 2, 40, and 100. Since it's rarely actually a 1, but it can be easier than a 3, sometimes we settle on 2. 40 and 100 must be broken down, and we often use them for placeholder epics.