Earned Schedule: time-based schedule performance
5 min read · Updated 22 Jun 2026
Why Earned Schedule?
Traditional EVM uses cost to measure schedule performance: SPI = EV ÷ PV. That works early in a project, but on a near-complete project where PV ≈ EV, SPI converges toward 1.0 regardless of how late you are — it loses its signal exactly when you most need it. Earned Schedule measures schedule slippage in time instead: how many months of progress has the project actually earned, versus how many months have elapsed?
The four metrics
- ES (Earned Schedule) — the point on the time axis where the planned-value curve equals the current earned value. In plain terms: the amount of schedule (in time units) that has been earned. If you are behind, ES < AT.
- AT (Actual Time) — elapsed time since the project baseline date. The clock reading, in the same units as ES.
- SV(t) (Schedule Variance in time) — ES − AT. Negative means behind schedule; positive means ahead. Expressed in time units (weeks, months) rather than money, so it stays interpretable to project completion.
- SPI(t) (Schedule Performance Index in time) — ES ÷ AT. Below 1.0 means the project is earning schedule slower than time is passing; above 1.0 means it's ahead.
How WBSync computes it
WBSync needs two inputs:
- The baseline plan — the time-phased distribution of planned value (PV curve) from the project's baseline contract dates and approved budget hours. WBSync builds this from the WBS node start / finish dates and budgeted hours.
- Approved hours to date — the earned value curve, built from all approved labour entries up to today.
It then finds the point on the PV curve that corresponds to the current EV — that point's time coordinate is ES. AT is simply today minus the baseline start date. All arithmetic follows the PMI Earned Schedule Practice Standard (Lipke, 2003; ISO 21508).
Where to find it
ES, AT, SV(t) and SPI(t) appear alongside the cost-based KPIs (SPI, CPI, EAC) in the KPI grid. They are only shown if you have cost-view access.
The EV Curves section of the dashboard plots the ES timeline alongside the PV and EV S-curves so you can see visually where the earned schedule falls relative to actual time.
The scheduled weekly progress PDF includes the Earned Schedule metrics in its EVM summary section.
What next?
See the full set of EVM metrics on the dashboard: Reports & dashboards →
Frequently asked
Why does WBSync use Earned Schedule instead of just SPI?
Cost-based SPI (EV ÷ PV) loses its signal late in a project — it converges toward 1.0 as PV approaches the budget at completion, regardless of how late you are. SPI(t) stays meaningful through project completion because it measures time earned vs time elapsed, not cost earned vs cost planned.
What is the difference between SPI and SPI(t)?
SPI = EV ÷ PV (cost-based schedule performance). SPI(t) = ES ÷ AT (time-based schedule performance). Both measure whether the project is ahead or behind schedule, but SPI(t) remains accurate to project completion; SPI does not.
What does a negative SV(t) mean?
The project is behind schedule. SV(t) = ES − AT; a negative value means the project has earned fewer time units of schedule than have actually elapsed. The magnitude tells you by how much (in weeks or months).
Who can see Earned Schedule metrics?
Anyone with can_view_costs access — QS, PM, Owner, Admin. Foremen, engineers, supervisors and operatives do not see the ES metrics, consistent with all other cost-gated KPIs.
What if the project has no baseline dates set?
Earned Schedule requires a time-phased PV curve, which is built from the WBS node baseline start/finish dates. If baseline dates are not set, the ES metrics will be unavailable and the dashboard will show a prompt to set the project baseline.
Is Earned Schedule available on all plans?
Yes, on any plan that includes EVM reporting (Field and above). It is gated by role (can_view_costs), not by plan tier.