Compare Two Versions of a Primavera P6 or Microsoft Project Schedule
Pick last month's update and this month's, and XER Reader lists what changed between them: activities added and deleted, dates, durations, logic, progress and the critical path. No Primavera P6 or Microsoft Project licence is needed.
| Activity ID | Activity Name | Change | What Changed | From | To | Difference |
|---|---|---|---|---|---|---|
| A1010 | Site mobilisation | Actuals Changed | Actual Start | 16-Feb-26 | 23-Feb-26 | +7d |
| A1020 | Excavation | Progress | Actual Finish | 20-Mar-26 | ||
| A1020 | Excavation | Progress | % Complete | 60% | 100% | +40% |
| A1040 | Pour foundations | Dates | Start | 09-Mar-26 | 16-Mar-26 | +7d |
| A1040 | Pour foundations | Dates | Finish | 27-Mar-26 | 10-Apr-26 | +14d |
| A1040 | Pour foundations | Critical | Became critical | 6d | 0d | -6d |
| A1050 | Erect steel frame | Duration | Original Duration | 20d | 25d | +5d |
| A1055 | Temporary roof protection | Added | Activity | |||
| A1060 | Roof cladding | Logic | Predecessor A1055 added | FS | ||
| A1300 | Handover | Constraint | Primary Constraint | Finish On 13-Nov-26 | Finish On 27-Nov-26 | +14d |
An illustration of the Compare Baseline tool with sample figures: two monthly updates of one schedule, and the first rows of the list of changes.
Fifteen Kinds of Change, Each With Its Own Button
Each kind has a button with its count. A click narrows the list to that kind, and a second click shows everything again. Rest the pointer on a button and it says what the kind covers.
| Kind | A change is |
|---|---|
| Added | An activity only the later version has. |
| Deleted | An activity only the earlier version has. |
| Renamed | A new activity name, or a new Activity ID when the activities are matched by GUID. |
| Type | A new activity type, such as a task that became a milestone. |
| Dates | A start or a finish that moved, counted in calendar days. |
| Duration | A new original or remaining duration. |
| Progress | An actual start or finish reported for the first time, or a new % complete, read by the activity's own % complete type. |
| Actuals Changed | An actual date the earlier version reported, now changed or removed. Shown in amber, as a warning. |
| Logic | A predecessor added or removed, or a new relationship type or lag. |
| Constraint | A primary or secondary constraint added, removed or changed, with how far its date moved. |
| Calendar | An activity on another calendar, or a calendar with new working time. |
| Code | An activity code value added, removed or changed. |
| Resource | A resource or role assigned or removed, or new budgeted units or cost. |
| Expense | An expense item added or removed, or a new budgeted cost. |
| Critical | An activity that became critical, or is no longer critical. |
One Row per Change, or One per Activity
Two radio buttons above the list switch between the views. Both have a filter on every column.
By Change
Each change on its own row: Activity ID, Activity Name, the kind of change, what changed, its value in each version, and the difference. The difference sorts and filters as a number.
By Activity
Each activity with a change once, with how many changes it has and of what kinds, and its start, finish, original duration, total float and % complete in each version, beside how far its finish moved.
Saved to Excel
A workbook of three sheets: a Summary of the two versions with the count of each kind, the Changes, and the Activities, each with a filter on every column. Differences are numbers Excel can sort, and each says what it counts.
Double click a row and the tool closes with that activity selected in the Activity view, when its project is open.
What to Know About the Comparison
A monthly update is usually a copy of the last one with progress added. The tool is built around that.
Activities are matched by Activity ID
As in Primavera P6. When both versions keep their GUIDs, as two exports of one P6 project do, the GUID is used instead, so an activity whose ID changed is listed as renamed rather than deleted and added.
Rewritten actuals stand out
An actual start or finish reported in the earlier update and changed or removed in the later one is a kind of its own, in amber. A line above the list says how many there are, and a click lists them.
Critical as each project defines it
Became critical and No longer critical follow each project's own setting: a total float up to its limit, or the longest path. Preferences can set one rule for every project instead. A completed activity is never critical.
New activities do not bury the list
An added activity brings its own predecessors, and they can be most of the logic changes. They are left out of the list, its counts and the Excel file until you tick the box that says how many there are.
Any Two Projects XER Reader Holds
Open the later version, then import the earlier one beside it with Manage Baseline. The + button in the tool's title bar opens it too.
Primavera P6
An XER that holds several projects, such as monthly copies kept in one export, brings them all in at once.
- Each project listed with its data date, since two versions of one schedule often share a name
- Activity codes, resources, roles, expenses and calendars compared, as well as dates and logic
- A changed relationship listed on its successor, with its old and new type and lag
Microsoft Project
Two saves of one Microsoft Project schedule compare the same way, with one thing to know about how tasks are matched.
- A task is matched by its outline number, unless the file carries activity IDs of its own
- So a task moved in the outline, or indented under a new summary, shows as deleted and added
Common Questions About Comparing Schedules
What you need, and what the comparison leaves out.
Do I need Primavera P6 to compare two XER files?
Which edition has Compare Baseline?
What does the comparison leave out?
Can the people I share a schedule with compare versions?
Does my schedule get uploaded?
See What Changed Since Last Month
Open this month's update, import last month's, and click Compare Baseline on the Tools tab. Importing a version is described in How to Assign and Manage Baselines.