SV (Schedule Variance)
Schedule Variance (SV) is earned value (EV) minus planned value (PV). Negative SV means less value is complete than was planned through the status date — the schedule is behind.
How it is computed
SV = EV − PV: earned value minus planned value. With week-5 planned value at $50k and completed value at $40k, SV is −$10k — $10k of the value planned through the status date has not been earned yet. Zero means on plan, negative means behind, positive means ahead. To see the same information as a ratio, use the Schedule Performance Index, SPI = EV ÷ PV — 0.8 in the example. SV shows the size of the gap; SPI shows its proportion. They are a pair.
Why it matters
It states the delay as an amount of value rather than an adjective. "The schedule slipped" says nothing about how much; "SV is −$10k" suggests the scale of the recovery effort. Across projects of different sizes, SPI compares better; within one project, SV tracks the absolute size of the slip better. Recorded every reporting period, the SV trend shows in one line whether the delay is growing or being recovered.
Common misconceptions
The most frequent mistake is reading SV as a duration. SV is a variance in value, not in dates. A −$10k SV off the critical path moves no finish date, while a small SV on the critical path pushes the finish date all the same — completion outlook belongs to the critical path and remaining-work dates. Also, near the end of a project PV reaches the budget total and stops, so SV converges to zero even on a badly late project. A late-stage SV improvement can be a property of the formula, not a recovery.
wbsgantt's Overview shows SV in weight percent on the SPI card ('SV −10% vs plan'), and the Top Delay card drills into the five tasks with the worst weighted SV.