Primavera P6 Baselines Explained: Set, Compare, Maintain
What Is a Baseline in Primavera P6?
A baseline in Primavera P6 is a snapshot of your project schedule at a specific point in time. It captures the planned start and finish dates, durations, relationships, and resource/cost assignments. Once approved, the baseline becomes the reference against which you measure actual progress. Without a baseline, you have no way to objectively answer “Are we on schedule?” or “Are we over budget?”
P6 allows you to store up to 50 baselines per project. The first one you create is typically the “Original Baseline” – the approved plan. Later you may create “Current Baseline” or “Target Baseline” copies to reflect re-baselining events.
How to Set and Assign a Baseline
Setting a baseline is straightforward but requires care. Follow these steps:
- Finalise your schedule – Ensure all logic ties, durations are realistic, and the project is resource-loaded if you plan to track costs.
- Create the baseline – Go to Project > Maintain Baselines. Click Add, give it a meaningful name (e.g., “Original Baseline v1.0”), and click OK.
- Assign the baseline – In the same window, highlight the baseline and click Assign. This makes it the “Project Baseline” that appears in columns and reports.
- Update the baseline data – After assigning, go to Project > Baseline > Update Baselines. Select the baseline and click Update. This copies the current schedule data into the baseline.
Pro tip: Always update the baseline immediately after creating it. Many users forget and end up with an empty baseline, causing zero variance.
Comparing Current vs Baseline (Variance)
Once you have a baseline, you can compare your current schedule against it. P6 offers several ways to see variance:
- Columns – Add columns like Baseline Start, Baseline Finish, Start Variance, Finish Variance. Positive variance means the activity is ahead of plan; negative means behind.
- Bar chart formatting – Set the timescale to show both the current bar and the baseline bar (usually in a different colour). This gives a visual of where the schedule has slipped.
- Reports – Use the built-in “Schedule Comparison” report or create a custom report to show variance for all activities.
- Earned Value Management (EVM) – With a cost-loaded baseline, you can compute Schedule Variance (SV) and Cost Variance (CV) using EVM metrics.
For example, if Activity A has a Baseline Finish of 01-Jun-2025 but the Current Finish is 15-Jun-2025, the Finish Variance is -14 days. That’s a clear signal the activity is behind.
Common Baseline Mistakes That Ruin Reporting
Even experienced schedulers make these errors. Avoid them to keep your reporting reliable:
| Mistake | Consequence | How to Avoid |
|---|---|---|
| Not updating baseline after creation | Baseline is empty; all variance is zero or nonsense. | Always run Update Baselines immediately after assigning. |
| Overwriting the original baseline | Lose the approved plan; cannot measure true variance. | Create a new baseline copy instead of updating the original. |
| Using multiple baselines inconsistently | Confusion over which baseline is the reference. | Clearly label baselines (e.g., “Original”, “Rebaseline v2”) and assign only one as the primary. |
| Editing baseline data directly | Corrupts the baseline; variance becomes meaningless. | Baselines are read-only after creation; never modify them manually. |
| Ignoring resource/cost baseline | Cost variance reports show no data. | Ensure the schedule is resource-loaded before creating the baseline. |
How to Maintain Baselines Over Time
Projects change. When a major change occurs (e.g., scope change, delay beyond a threshold), you may need to re-baseline. Best practice:
- Never delete the original baseline. Keep it for historical comparison.
- Create a new baseline copy (e.g., “Rebaseline 01-Jan-2025”) and assign it as the new target.
- Document the reason for re-baselining in a project note or separate log.
- Use the “Baseline Comparison” feature in P6 to compare the new baseline against the original to show the impact of changes.
You can also use tools like Project Assure – a free, browser-based Primavera P6 XER schedule analyser – to run DCMA 14-point, GAO & NASA checks, EVM/S-curve, and forensic baseline-vs-update comparison. Nothing is uploaded; your XER is parsed locally in the browser, making it safe and fast.
Conclusion
Baselines are the backbone of schedule control in Primavera P6. Set them correctly, compare variance diligently, and avoid common pitfalls. With a solid baseline, you can track progress, communicate delays, and keep stakeholders informed. For a deeper dive into baseline health, run your XER through Project Assure to spot issues before they become problems.
Run these checks free, in your browser
Free, browser-based Primavera P6 XER schedule analyser — DCMA 14-point, GAO & NASA checks, EVM/S-curve, and forensic baseline-vs-update comparison. Nothing is uploaded; your XER is parsed locally in the browser. 3 free analyses, no card required.
Analyse your XER →Frequently asked questions
What is a baseline in Primavera P6?
A baseline is a snapshot of your project schedule at a specific point in time. It captures planned dates, durations, relationships, and costs, and serves as the reference for measuring progress and variance.
How do I set a baseline in Primavera P6?
Go to Project > Maintain Baselines, add a new baseline with a name, assign it, then update it via Project > Baseline > Update Baselines. Always update immediately after creation to copy current data.
What is variance in P6 and how do I see it?
Variance is the difference between current dates and baseline dates. Add columns like 'Start Variance' and 'Finish Variance' to your activity table, or use bar chart formatting to show both bars.
Can I have multiple baselines in one project?
Yes, P6 allows up to 50 baselines per project. Keep the original for history and create new ones for major re-baselining events. Label them clearly and assign only one as the primary target.
What happens if I forget to update the baseline?
The baseline will be empty, causing all variance columns to show zero or incorrect values. Always run 'Update Baselines' immediately after creating or assigning a baseline.