Cost Variance (CV) measures the dollar difference between the value of work actually completed and the money actually spent to complete it. A negative CV signals a project is over budget; a positive CV signals a project is under budget. CV is a to-date measurement, calculated at any point during execution, not a forecast of final project cost.
What Is Cost Variance (CV) in Project Management?
Cost Variance (CV) is the dollar difference between Earned Value and Actual Cost, measuring whether a project is currently over or under budget. CV belongs to the Project Cost Management knowledge area and functions as a core input to cost control throughout project execution.
What Is the Cost Variance Formula?
The Cost Variance formula is CV = EV − AC, where EV is Earned Value and AC is Actual Cost. Both inputs must reflect the same reporting date for the calculation to produce an accurate result.
How Do You Calculate Cost Variance?
A project manager calculates Cost Variance by subtracting Actual Cost from Earned Value at a given reporting date.
A marketing campaign project has a total budget of $80,000. At the current reporting date, the team has completed 40% of the planned work and has spent $36,000.
EV = 40% × $80,000 = $32,000 AC = $36,000 CV = $32,000 − $36,000 = −$4,000
A CV of −$4,000 indicates the project is currently $4,000 over budget relative to the value of work completed.
How Do You Interpret Cost Variance?
A negative CV indicates the project is over budget, a positive CV indicates the project is under budget, and a CV of zero indicates the project is exactly on budget. A CV of exactly zero is rare in practice, since actual spending almost never matches earned value precisely.
- CV < 0 — the project is over budget; more was spent than the value of work completed.
- CV > 0 — the project is under budget; less was spent than the value of work completed.
- CV = 0 — the project is exactly on budget.
What Is the Difference Between Point-in-Time and Cumulative Cost Variance?
Point-in-time CV measures cost performance for a single reporting period alone, while cumulative CV measures cost performance across all periods combined, and the two can tell very different stories about the same project. A healthy cumulative CV can mask a serious overrun in a single period, if an earlier or later period compensates for it.
A project has a $12,000 budget tracked monthly:
- Month 1: 10% cumulative complete, $1,000 cumulative spent. Cumulative EV = $1,200. Cumulative CV = $1,200 − $1,000 = +$200.
- Month 2: 22% cumulative complete, $2,700 cumulative spent. Cumulative EV = $2,640. Cumulative CV = $2,640 − $2,700 = −$60.
- Month 3: 35% cumulative complete, $4,000 cumulative spent. Cumulative EV = $4,200. Cumulative CV = $4,200 − $4,000 = +$200.
Isolating Month 2’s point-in-time performance tells a sharper story. Work completed that month alone was 12% (22% − 10%), and money spent that month alone was $1,700 ($2,700 − $1,000).
Point-in-Time EV (Month 2) = 12% × $12,000 = $1,440 Point-in-Time CV (Month 2) = $1,440 − $1,700 = −$260
Month 2 ran $260 over budget on its own, a signal the cumulative CV alone never revealed, since Month 3’s strong performance offset it in the running total.
How Does Variance at Completion (VAC) Relate to Cost Variance?
Variance at Completion (VAC) is not a type of Cost Variance — it is a separate, forward-looking forecast calculated as BAC minus EAC, projecting the budget variance expected at project close. Point-in-time and cumulative CV both measure performance to date; VAC forecasts an outcome that has not happened yet. Grouping VAC alongside the two CV types as interchangeable measurements blurs a distinction the PMP exam tests directly.
How Does Cost Variance Relate to Cost Performance Index (CPI)?
Cost Variance expresses budget performance as a dollar amount, while Cost Performance Index expresses the same underlying data as an efficiency ratio, calculated as CPI = EV / AC. A related metric, Cost Variance Percentage (CVP = CV / EV × 100), converts the dollar figure into a percentage for easier comparison across projects of different sizes.
How Does Cost Variance Compare to Schedule Variance (SV)?
Cost Variance isolates budget performance using EV and AC, while Schedule Variance isolates timeline performance using EV and PV, and a project can show favorable results on one measure while showing unfavorable results on the other. A project running under budget is not necessarily on schedule, and a project running on schedule is not necessarily on budget — the two variances must be read together for a complete performance picture.
What Causes Cost Variances?
Cost variances typically originate from labor, materials, unplanned damage, or overhead costs deviating from their original estimates. Identifying which category drove a variance is the first step toward corrective action.
- Labor cost variance occurs when actual hours worked or labor rates differ from the original estimate, often from underestimated task complexity.
- Material cost variance occurs when raw material or supply costs shift due to market pricing changes or unexpected waste.
- Unplanned damage or rework occurs when equipment failure, errors, or accidents require unbudgeted repair or replacement spending.
- Overhead cost variance occurs when shared costs such as facilities, utilities, or administrative overhead run higher than planned.
What Common Mistakes Do Project Managers Make With Cost Variance?
The most common Cost Variance mistakes involve confusing CV with CPI, treating VAC as a period-based CV type, and relying on cumulative CV alone without checking individual periods. Each mistake risks missing a real budget problem hiding inside an otherwise healthy-looking number.
- Confusing CV, a dollar figure, with CPI, a ratio — the two are related but not interchangeable.
- Classifying VAC as a type of Cost Variance rather than a distinct end-of-project forecast.
- Reviewing only cumulative CV, missing a single bad period masked by strong performance elsewhere.
- Identifying a negative CV without following up with root-cause analysis and corrective action.
How Does Cost Variance Appear on the PMP Exam?
The PMP exam tests Cost Variance through direct calculation questions, interpretation questions, and questions requiring candidates to distinguish CV from CPI or from VAC. Exam scenarios frequently supply more data than needed, requiring candidates to identify which figures actually apply to the CV calculation.
Sample Question 1: A project has AC = $18,500 and EV = $17,200. What is the Cost Variance, and what does it indicate? A) $1,300; the project is under budget B) −$1,300; the project is over budget C) $1,300; the project is over budget D) −$1,300; the project is under budget
Sample Question 2: A project is budgeted at $90,000 across 6 equal months. At the end of month 2, the project is exactly on schedule, and $32,000 has been spent. What is the Cost Variance? A) $2,000 B) −$2,000 C) $30,000 D) $32,000
Sample Question 3: A project manager reports a cumulative CV of +$500 through month 4, but month 4’s point-in-time CV alone is −$1,200. What does this indicate? A) The project has no budget concerns at all B) Prior months performed well enough to offset a real overrun in month 4 C) The calculation contains an error, since both figures cannot be true D) Month 4’s overrun means the cumulative CV is also negative
Sample Question 4: A stakeholder asks for the project’s forecasted budget variance at completion, not its current cost performance. Which metric should the project manager provide? A) Cumulative CV B) Point-in-time CV C) CPI D) VAC
Answers: 1) B — CV = EV − AC = $17,200 − $18,500 = −$1,300, indicating the project is over budget. 2) B — with the project on schedule at month 2 (33.3% complete), EV = $30,000; CV = $30,000 − $32,000 = −$2,000. 3) B — cumulative CV can remain positive even when a specific period runs over budget, if earlier periods performed well enough to offset it. 4) D — VAC is the forward-looking forecast of budget variance at project completion, distinct from CV, which measures performance to date.
Frequently Asked Questions
Is Cost Variance the Same as Cost Performance Index?
Cost Variance and Cost Performance Index are related but distinct: CV expresses budget performance as a dollar amount (EV − AC), while CPI expresses the same data as a ratio (EV / AC). A project can have a small CV in dollar terms but a meaningfully high or low CPI, depending on the project’s overall size.
Can Cost Variance Be Zero?
Cost Variance can be zero, indicating Earned Value and Actual Cost are exactly equal, but this outcome is rare in real project data. A CV very close to zero is a more realistic sign of strong budget control than an exact zero.
What Does a Negative Cost Variance Mean for a Project’s Future?
A negative Cost Variance signals the project is currently over budget, and if the underlying cause continues unaddressed, the trend typically carries forward into future reporting periods and the project’s final cost forecast. Identifying and correcting the root cause early prevents a small overrun from compounding into a significant one.
Is Variance at Completion a Type of Cost Variance?
Variance at Completion is not a type of Cost Variance — it is a separate forecasting metric calculated as BAC minus EAC, projecting the expected budget outcome at project close rather than measuring performance to date. Treating VAC as interchangeable with point-in-time or cumulative CV is a common source of confusion on the PMP exam.
