Schedule Variance (SV)
How Schedule Variance Works
Schedule variance is an earned value metric that expresses how far ahead or behind schedule a project is in dollar terms. The formula is SV = EV minus PV. A positive SV means the project is ahead of schedule: more work has been completed than planned. A negative SV means the project is behind schedule: less work is done than the plan called for at this point. An SV of zero means the project is exactly on schedule.
SV expresses schedule deviation in dollar terms, which can feel counterintuitive (schedule is usually measured in days or weeks, not dollars). The dollar value represents how much budgeted work is ahead or behind. A negative SV of $20,000 means $20,000 worth of planned work has not yet been completed.
How to Calculate SV
SV = EV minus PV. Example: At Month 3, the baseline says $120,000 of work should be complete (PV = $120,000). The team has completed work budgeted at $105,000 (EV = $105,000). SV = $105,000 minus $120,000 = negative $15,000. The project is behind schedule by $15,000 worth of planned work.
When to Use SV vs SPI
Use SV when communicating the magnitude of a schedule gap in terms stakeholders can relate to budget conversations. Use SPI for trend analysis and efficiency comparisons across time periods. Like CV and CPI, SV gives magnitude while SPI gives rate.
SV shares the same convergence limitation as SPI: it approaches zero as the project nears completion regardless of how late the project is. This makes SV most reliable in the first half of the project. For late stage schedule analysis, use critical path slack and SPI(t).
When SV Is Less Useful
SV does not tell you which tasks are behind or whether the delay affects the critical path. A negative SV could result from delays on non critical tasks (no impact on end date) or delays on the critical path (project end date at risk). Pair SV with critical path analysis to determine the actual schedule risk.
Commonly Confused With
| Term | Key Difference |
|---|---|
| SPI (Schedule Performance Index) | SV is an absolute dollar amount (EV minus PV). SPI is a ratio (EV / PV). SV shows how much work is ahead or behind. SPI shows the rate of schedule efficiency. |
| Cost Variance (CV) → | SV measures schedule deviation (EV minus PV). CV measures cost deviation (EV minus AC). Both use EV but compare it to different baselines. |
| Schedule Slip | Schedule slip is measured in time units (days, weeks). SV is measured in dollar terms. A negative SV of $20,000 means $20,000 worth of planned work is not yet complete, but does not directly indicate how many days late the project is. |