Make every comparison
easier to understand.

Any two related Microsoft Project schedules you want to assess against each other. They might be consecutive programme updates, a baseline and forecast, an original and revised programme, a recovery programme, or two alternative scenarios.

The schedules do not need to be consecutive versions.

No. Reference is the schedule you want to use as the basis of the comparison. Comparison is assessed against it.

Reversing the files can reverse added and removed activities or earlier and later date movements.

For meaningful activity-level results, the schedules should generally represent the same project, programme or scenario, with enough common work for activities to be aligned.

Substantially different schedules can still be compared, but differences in scope or structure may result in more activities being shown as added or removed.

No. GanttScan reads the schedule information required for the comparison. It does not write changes back to either uploaded .mpp file.

Not currently. The current comparison tool accepts Microsoft Project .mpp files.

GanttScan reads the schedule information in both Microsoft Project files, aligns corresponding activities and compares the relevant schedule fields.

The analysis is deterministic: the same two files, in the same Reference and Comparison order, produce the same analysis. GanttScan does not use AI to invent schedule values or guess unsupported changes.

No. GanttScan compares the information read from the supplied files. It does not replace Microsoft Project’s scheduling engine or independently reschedule the programme.

For the clearest comparison, recalculate and save schedules in Microsoft Project before upload.

Yes. Calendars, manually scheduled activities, constraints, logic, progress entry and critical-path settings can affect the values in the supplied files.

GanttScan identifies differences; it does not determine whether the underlying scheduling approach is correct.

Automated comparison cannot understand every project context. Activity matching requires the most judgement: extensive restructuring, duplicate activities, major renaming or changes to several attributes at once can make correspondence less clear.

Review important findings in the context of the project.

GanttScan reports what changed. A later finish, a newly critical activity or a logic change may be important, but its significance depends on the project.

It does not judge whether the revised plan is appropriate or beneficial.

GanttScan does not rely on the visible Microsoft Project row ID alone. It uses activity identity and wider schedule context to align corresponding activities before comparing them.

Normal ID movement caused by inserting, deleting or reorganising activities does not automatically make an activity appear removed and re-added.

Yes, where the two schedules provide enough consistent evidence that their Unique IDs correspond. Individual matches are also checked against activity context.

A matching Unique ID is not accepted blindly. GanttScan can use other schedule characteristics when Unique IDs are missing, inconsistent or unsuitable.

A renamed activity can still be matched using the wider schedule context; a changed name does not automatically make it new.

A major rename combined with other substantial changes may prevent a reliable match. Review important differences in the project context.

Names form part of matching, but duplicate or generic names can make activities harder to distinguish. GanttScan also considers their context within the schedule.

Similar names do not guarantee a match, and extensive duplication can leave activities shown as added or removed.

An Added Activity exists in the Comparison Schedule but was not aligned to an activity in the Reference Schedule.

A Removed Activity exists in the Reference Schedule but was not aligned to an activity in the Comparison Schedule.

In the dashboard, a structural change is a detected change to an existing activity’s duration, predecessor logic links or constraints.

GanttScan shows the Reference and Comparison values so you can review the difference directly. Name and row-ID changes are not listed in this section.

Summary rows are excluded from activity-level analysis, so rolled-up information is not treated as separate work. Their hierarchy can still help align the underlying activities.

The overall project summary provides the project finish when that value is available in the file.

Yes. Milestones that are not summary rows are included as activities and can appear in critical activity analysis when marked critical.

GanttScan uses the Microsoft Project % Complete field to compare recorded activity progress. It does not infer progress from today’s date or assume work has started because its planned start date has passed.

The tracker shows starts, completions, increases, decreases in % Complete and unchanged in-progress work. The PDF includes the progress comparison too.

No. The current comparison uses % Complete, rather than Physical % Complete or Work % Complete.

The page shows no recorded progress when neither supplied schedule contains a valid % Complete value above 0%. GanttScan does not estimate progress from dates.

If progress exists but has not increased between matched activities, the tracker can instead show no progress movement.

An activity has a valid recorded % Complete greater than 0% and less than 100% in the Comparison Schedule. This can include added activities.

Activities with decreased progress also appear here when their Comparison value remains between 0% and 100%. An activity can appear in both a progress-change category and Currently In Progress.

GanttScan uses the Critical flag read from each supplied Microsoft Project file. It does not apply its own critical-slack threshold.

Microsoft Project’s criticality settings, including the slack threshold, can affect which activities carry that flag.

No. GanttScan compares the Critical flags read from the supplied schedules. The side-by-side list aligns critical activities for comparison; it is not a newly calculated path.

Criticality depends on the surrounding network and available float, as well as activity dates. Changes to logic, duration, neighbouring work, constraints, deadlines or scheduling settings can affect critical status.

GanttScan reports the difference without deciding what it means for the project.

Available float and the surrounding network can change even when an activity’s own dates stay the same. Changes elsewhere in the programme can therefore change its critical status.

The comparison reflects the Critical flags read from each file. Different Microsoft Project criticality settings may contribute to differences.

Where criticality is important to the review, check the settings used for both schedules.

Date movements are calendar-day differences between the recorded dates and times. A positive movement means later; a negative movement means earlier. Time-of-day differences can produce fractional days, even though dates are displayed without times.

Activity durations and logic-link lags retain the units read from Microsoft Project, including working or elapsed units where supplied. GanttScan does not convert these values into calendar days or normalise them onto a common calendar.

Yes. Calendars affect the dates Microsoft Project calculates, so different working calendars can produce different dates even where duration or logic appears similar.

GanttScan compares the values read from each file; it does not normalise the schedules onto a common calendar.

GanttScan compares the values that can be read from the file. Manually scheduled activities may not respond to logic or calendars in the same way as automatically scheduled activities.

Missing or unreadable date values are not inferred from the surrounding programme.

GanttScan compares an activity’s predecessor links: which activities are linked, the relationship type and the lag. Added, removed or changed links can appear as structural changes.

The supported relationship types include finish to start, start to start, finish to finish and start to finish. Matched activity identities are used so normal renumbering alone is not treated as a link change.

It means the project finish read from the Comparison Schedule is later than the finish in the Reference Schedule.

The movement alone does not establish its cause, responsibility or contractual delay entitlement.

No. GanttScan identifies schedule movement; it does not determine extension-of-time entitlement, concurrency, responsibility, excusable delay or compensable delay.

Those questions require a separate review of the contract, project events and supporting records.

Activity, logic, progress and criticality differences provide a starting point for investigating the revised schedule.

GanttScan does not automatically determine which change caused the completion date to move.

The current comparison tool accepts genuine Microsoft Project .mpp files. Each uploaded file must be no larger than 25 MB.

Check that the file opens normally in Microsoft Project and has been saved as a genuine .mpp file.

Renaming another file type to .mpp does not create a Microsoft Project schedule.

The free tool uses temporary uploaded files to read the schedule information required for your comparison, then deletes those files when processing finishes.

It does not create a saved project or schedule history.

To let you generate the PDF, a copy of the completed comparison results is held temporarily in server memory for up to 30 minutes. It is available only to the browser session that performed the comparison.

These results are not saved as project history. If the report is no longer available, compare the schedules again.

No. The free comparison tool does not use uploaded schedules or extracted schedule information to train AI models.

No. The current comparison is rule-based and deterministic.

Yes. After a successful comparison, select Generate report to download a branded PDF Schedule Comparison Report containing key findings and supporting detail.

Download it in the same browser session while the report is available.

Yes. The report provides a clear record of the schedule comparison.

Review important findings in the project context before relying on them for contractual or formal decisions.

Select New comparison at the top of the results page and choose another Reference and Comparison schedule.