Track schedule efficiency with earned value inputs. Forecast finish dates and quantify delay risk quickly. Export neat CSV and PDF summaries for onsite teams.
| Scenario | BAC | Planned % | Actual % | PV | EV | SPI | Interpretation |
|---|---|---|---|---|---|---|---|
| Residential remodel (status week 6) | 500,000 | 50% | 45% | 250,000 | 225,000 | 0.900 | Behind schedule |
| Commercial fit-out (status week 10) | 1,200,000 | 40% | 44% | 480,000 | 528,000 | 1.100 | Ahead of schedule |
Values are illustrative and should match your project reporting rules.
Schedule Performance Index measures schedule efficiency at a status date.
Use SPI alongside field notes, constraints, and approved change logs.
Accurate inputs turn schedule metrics into actionable insights.
Schedule Performance Index (SPI) converts progress into a clear efficiency signal. An SPI below 1.00 means the project is earning less progress than planned at the checkpoint, while values above 1.00 indicate outperformance. It helps teams spot slippage early and communicate it consistently. Because it is ratio-based, SPI stays comparable across budgets, phases, and reporting periods.
In earned value reporting, SPI uses EV (earned value) and PV (planned value). If BAC is 500,000 and the plan calls for 50% complete, PV equals 250,000. If measured completion is 45%, EV equals 225,000 and SPI is 0.90.
SPI shows efficiency; variance shows magnitude. SV = EV − PV. In the example, SV is −25,000, meaning the team has earned 25,000 less value than planned at the status date. A small SPI change can still hide a large variance on big projects.
Many teams treat 0.98–1.02 as “on track” to reduce noise. Values below 0.95 typically trigger deeper review: constraints, rework, access, crew balance, and procurement timing. Values above 1.05 can be positive, but verify that progress crediting is not overstated.
A simple forecast uses Estimated Duration ≈ Planned Duration ÷ SPI. With a 120‑day baseline and SPI of 0.90, the rough forecast becomes 133.33 days. Use this as an early warning and confirm with look‑ahead plans and critical path checks.
When EV data is unavailable, time-based SPI compares planned elapsed days to actual elapsed days up to a status date. It is easy to apply for small scopes, but it does not weight progress by scope complexity or budget, so interpret it carefully.
Define rules for percent complete, avoid counting deliveries as installed work, and keep PV aligned to the approved baseline. Weekly updates fit most active sites and support quick recovery moves, while long reporting gaps can delay decisions and worsen schedule drift.
Use SPI to drive a response plan: confirm the constraint, assign an owner, set a recovery target, and track it at the next status date. Pair SPI with safety, quality, and change control so productivity gains do not create rework or risk.
You’re earning about 90% of the planned progress at the checkpoint. It indicates the project is behind schedule relative to the baseline and may require recovery actions.
Usually it suggests work is completing faster than planned, but confirm progress crediting rules. Front-loading or inconsistent measurement can inflate EV and make SPI look better than reality.
SPI is a ratio (EV ÷ PV) showing efficiency. SV is a difference (EV − PV) showing the size of the gap at the status date. Use both together for context.
Yes. A time-based approach uses planned elapsed days divided by actual elapsed days to a status date. It’s simpler, but it doesn’t weight progress by scope or cost.
Weekly updates work well for active construction because they align with look-ahead planning. More frequent updates can be noisy; monthly updates may be too slow for recovery decisions.
PV should follow the approved baseline schedule and budget allocation. It should represent budgeted value of planned work by date, not invoices or delivered materials.
Validate the data first, then review constraints, productivity, sequencing, and procurement. Identify the critical drivers, assign owners, and create a targeted recovery plan with measurable milestones.
Plan smart, track progress, and finish projects on time.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.