Project Management guide · Scheduling and time
Project Milestones: Definition, Examples and How to Set Them
A project milestone is a significant point or event in a project, such as an approval, a handover or a go-live. Milestones have zero duration: they mark a moment in time rather than a piece of work.
Key takeaways
- Milestones are zero-duration points that mark significant events.
- Write them as completed states with clear completion criteria.
- Link them to activities so their dates calculate from the schedule.
- Report milestone forecasts against the baseline.
Milestones vs tasks vs deliverables
| Milestone | Task | Deliverable | |
|---|---|---|---|
| What it is | A point in time | Work that takes time | An output produced by the work |
| Duration | Zero | Hours to weeks | Not applicable |
| Example | Design signed off | Draft the design | The approved design document |
| On a Gantt chart | Diamond | Bar | Often linked to a milestone |
Common milestone examples
- Project charter approved; see project charter.
- Requirements signed off.
- Design approved.
- Contract awarded to a supplier.
- Build complete or code freeze.
- User acceptance testing passed.
- Go-live or launch.
- Project closed and handed over to operations; see project closure.
How to set milestones
- Look for points where a decision is made, a phase ends, or something is handed to another party.
- Write each milestone as a completed state, for example "Supplier contract signed" rather than "Sign contract".
- Link each milestone to the activities that must finish first so its date calculates.
- Agree clear completion criteria so there is no debate about whether it has been reached.
- Keep the number manageable: a handful per phase is usually enough for reporting.
- Mark the milestones that the sponsor or customer care about most and report against them.
Worked example
A website redesign planned over 12 weeks might use these milestones:
| Milestone | Target | Completion criteria |
|---|---|---|
| Discovery complete | End of week 2 | Requirements document signed by product owner |
| Design approved | End of week 5 | Sponsor approves page designs |
| Build complete | End of week 9 | All pages pass internal testing |
| Launch | End of week 12 | Site live and monitoring in place |
If the design is approved at the end of week 6 instead of week 5, the milestone report shows one week of slippage immediately, even before the build is affected.
Tips for tracking milestones
- Report forecast against baseline dates for each milestone in your status report.
- Use a milestone trend chart to show how forecast dates move over time.
- Treat a missed milestone as a trigger for a recovery discussion, not just a note.
- Link payment milestones in contracts to clear acceptance criteria.
Free templates for this topic
Frequently asked questions
What is a project milestone?
A significant point in a project schedule, with zero duration, used to mark progress such as an approval or completion of a phase.
Do project milestones have a duration?
No. A milestone marks a moment in time. The work leading up to it is shown as tasks.
How many project milestones should you have?
There is no fixed number. Enough to show progress at meaningful points, typically a few per phase.
What is the difference between a project milestone and a deliverable?
A deliverable is an output; a milestone is the moment something happens, such as the deliverable being accepted. See project deliverables.
What is a project milestone chart?
A simple chart that shows only milestones on a timeline, useful for senior stakeholders; see project timeline.
What is a payment milestone in a project milestone plan?
A contract milestone that triggers a payment when the agreed work is accepted.
How do you show project milestones on a Gantt chart?
As diamond symbols. In most tools you create them by setting a task's duration to zero; see Gantt chart.
Can a project milestone be on the critical path?
Yes. Milestones linked to critical activities are on the critical path and any delay to them delays the project.
What is the difference between a project milestone and a phase gate?
A phase gate is a type of milestone where a formal go or no-go decision is made before the next phase starts.
Are project milestones used in Agile?
Yes. Agile teams often use release dates, sprint reviews or product launches as milestones on an agile roadmap.