This post goes over how to estimate when an epic will be done.
T-Shirt
T-shirt size provides a rough estimate of how long it would take a delivery team to finish an epic.
| Size | Time |
|---|---|
| XS | 0-1 weeks |
| S | 2-4 weeks |
| M | 5-8 weeks |
| L | 9-12 weeks |
| XL | +13 weeks |
Since the t-shirt size is a high-level estimate, it’s usually given before a technical design or story breakdown (ticket creation) is done.
Ticket Count
If you’re doing Scrum/Kanban, you can check your Agile report to see how long it takes a developer to complete a ticket.
Example
1 developer closes 1 ticket every 1 week and epic has 10 tickets:
- 10 tickets / 1 developer = 10 weeks
- 10 tickets / 2 developers = 5 weeks
- 10 tickets / 3 developers = 3.3 weeks
Story Points
If you’re doing Scrum/Kanban, you can check your Agile report to see how many story points a developer completes in a week.
Example
1 developer does 3 points every 1 week and epic has 30 points (10 tickets × 3 points):
- 30 points / (1 developer × 3 points) = 10 weeks
- 30 tickets / (2 developers × 3 points) = 5 weeks
- 30 tickets / (3 developers × 3 points) = 3.3 weeks
Monte Carlo
If you have existing data, you can run a Monte Carlo simulation.
If you’re using Jira, you can use the ActionableAgile plugin charts:
Buffer
Once your epic has a target date, you should always add a buffer because it’s rare for projects to complete on time since there are always interrupts, changes, and bugs.
| Outlook | Buffer |
|---|---|
| Optimistic | 1.25x |
| Conservative | 1.5x |
| Pessimistic | 2x |
Example
Given an epic is estimated to take 10 weeks to complete:
- Optimistic = 10 weeks × 1.25 = 12.5 weeks
- Conservative = 10 weeks × 1.5 = 15 weeks
- Pessimistic = 10 weeks × 2 = 20 weeks