Last reviewed 16 Sept 2026 · 7 min read
Why software?
Manual CPM/PERT calculations become impractical for projects with hundreds or thousands of activities. Project management software:
- Computes schedules, critical paths and floats automatically.
- Manages resources and costs, levelling and cash flow.
- Stores baselines and tracks progress; performs earned value analysis.
- Produces reports (Gantt charts, histograms, S-curves) and supports what-if analysis.
- Enables multi-project and multi-user planning (enterprise tools).
General workflow
- Set up the project — start date, calendars (working days, hours, holidays).
- Create the WBS (summary levels).
- Add activities (tasks) with durations.
- Define relationships (FS, SS, FF, SF) and lags/leads.
- Apply constraints only where necessary (imposed dates).
- Schedule — compute early/late dates, float, critical path.
- Define and assign resources (labour, equipment, materials) and costs.
- Level resources if overallocated.
- Save a baseline (approved plan).
- Update progress periodically (actual start/finish, % complete, remaining duration) at a data date/status date; reschedule.
- Compare with baseline; analyse variances; report.
Microsoft Project
A desktop (and cloud) tool widely used for small to medium projects; files typically saved as .mpp.
Key views
| View | Use |
|---|---|
| Gantt Chart | Task table with bars on a timescale; links shown |
| Tracking Gantt | Current schedule bars compared with baseline bars |
| Network Diagram | Tasks as boxes (activity-on-node) with dependencies |
| Resource Sheet | List of resources — type (work, material, cost), rates, maximum units |
| Resource Usage / Task Usage | Time-phased work per resource/task |
| Resource Graph | Histogram — shows overallocation |
| Calendar, Timeline | Overview displays |
Task types and the work formula
FormulaWork formula (MS Project)
- Fixed units — adding resources shortens duration (effort-driven) or keeps units constant when duration changes.
- Fixed duration — duration stays constant; changing work changes units.
- Fixed work — work stays constant; adding resources reduces duration.
Dependencies, lags and constraints
- Link types: Finish-to-Start (FS) (default), Start-to-Start (SS), Finish-to-Finish (FF), Start-to-Finish (SF); lag (positive, e.g. curing) or lead (negative lag).
- Constraints: As Soon As Possible (ASAP) (default for projects scheduled from the start date), As Late As Possible (ALAP), Start No Earlier Than (SNET), Start No Later Than (SNLT), Finish No Earlier Than (FNET), Finish No Later Than (FNLT), Must Start On (MSO), Must Finish On (MFO).
- Hard constraints (MSO, MFO) override logic and can create negative slack — use sparingly; deadlines are a softer alternative.
- Milestones — tasks of zero duration; summary tasks roll up subtasks; recurring tasks for repeated meetings.
Other features
- Critical path highlighting; total slack and free slack columns.
- Resource levelling — delays or splits tasks within slack (or beyond) to resolve overallocation.
- Baselines (up to 11) and interim plans; % complete, actual work, remaining duration.
- Earned value fields (BCWS, BCWP, ACWP, SV, CV, CPI, SPI).