Cost Variance (CV) and Schedule Variance (SV) are two core Earned Value Management (EVM) measures used to understand project performance. CV shows whether the completed work is costing more or less than its earned budget, while SV shows whether the project has completed more or less work than planned. Together, they help project teams identify performance problems early and take corrective action.
What Is Cost Variance?
Cost Variance (CV) measures the difference between the Earned Value (EV) of completed work and the Actual Cost (AC) spent to perform that work.
The formula is:
CV = EV − AC
The result tells you whether the project is performing better or worse than its cost baseline.
- Positive CV: The project is under budget for the work performed.
- Zero CV: Cost performance is exactly on plan.
- Negative CV: The project is over budget for the work performed.
For example, suppose a project has earned value of $80,000, but the actual cost of completing that work is $90,000.
CV = $80,000 − $90,000 = −$10,000
The negative $10,000 variance means the project has spent $10,000 more than the budgeted value of the work completed.
Cost variance is therefore a useful indicator for project controls teams monitoring whether project spending is aligned with the approved cost baseline.
What Is Schedule Variance?
Schedule Variance (SV) measures the difference between the Earned Value (EV) of completed work and the Planned Value (PV) of work that was scheduled to be completed.
The formula is:
SV = EV − PV
The result indicates whether the project has accomplished more or less work than planned at a particular point in time.
- Positive SV: More work has been earned than planned.
- Zero SV: Progress is aligned with the plan.
- Negative SV: Less work has been earned than planned.
For example, if the planned value is $100,000 and the earned value is $80,000:
SV = $80,000 − $100,000 = −$20,000
The negative result indicates that the project has completed less work than planned.
An important point is that traditional EVM schedule variance is expressed in value or monetary units, not directly in days or weeks. PMI research has highlighted this limitation and discusses earned schedule approaches for translating schedule performance into time-based measures.
Cost Variance vs Schedule Variance: The Key Difference
The simplest way to remember the difference is:
1. Cost Variance asks:
“Are we spending more or less than the value of the work we have completed?”
2. Schedule Variance asks:
“Have we completed more or less work than we planned to complete by now?”
The two measures use the same Earned Value (EV) but compare it with different project-control values.
- CV compares EV with AC.
- SV compares EV with PV.
This distinction is important because a project can be under budget but behind schedule, or over budget while still achieving more progress than planned.
Understanding PV, EV and AC
To calculate CV and SV correctly, you need to understand three basic EVM terms.
1. Planned Value (PV)
Planned Value is the authorized budget assigned to the work that was planned to be completed by a specific date.
In simple terms, PV answers:
“How much work did we plan to accomplish by now, measured in budgeted value?”
2. Earned Value (EV)
Earned Value is the budgeted value of the work that has actually been completed.
It answers:
“How much budgeted work have we actually accomplished?”
3. Actual Cost (AC)
Actual Cost is the cost actually incurred for the completed work.
It answers:
“How much have we actually spent to accomplish that work?”
PMI's EVM guidance uses these three values as the foundation for calculating cost and schedule performance.
Also read: WBS vs Project Schedule: Understanding the Difference
A Simple Example of CV and SV Together
Consider a project with the following status at the reporting date:
- Planned Value (PV): $100,000
- Earned Value (EV): $80,000
- Actual Cost (AC): $90,000
The Cost Variance is:
CV = EV − AC
CV = $80,000 − $90,000
CV = −$10,000
This indicates unfavorable cost performance.
The Schedule Variance is:
SV = EV − PV
SV = $80,000 − $100,000
SV = −$20,000
This indicates that the project has accomplished less work than planned.
The overall picture is therefore clear: the project is both over budget for the work performed and behind its planned progress.
This is where variance analysis becomes valuable. Rather than looking at one number in isolation, project professionals should investigate the reasons behind both variances.
Four Common CV and SV Scenarios
CV and SV become particularly useful when considered together.
1. Positive CV and Positive SV
The project is performing favorably on both measures.
It is costing less than the earned budget and has accomplished more work than planned.
However, the project team should still verify that progress measurements are accurate and that favorable performance is sustainable.
2. Negative CV and Negative SV
This is a warning situation.
The project is spending more than the value of the work completed while also accomplishing less work than planned.
Possible causes could include productivity problems, inaccurate estimates, resource constraints, procurement delays, rework, or technical issues.
3. Negative CV and Positive SV
The project is progressing faster than planned but at a higher cost.
This may happen when additional resources, overtime, premium procurement, or accelerated work are being used to protect the schedule.
The project team should determine whether the additional cost is justified by the schedule benefit.
4. Positive CV and Negative SV
The project is spending efficiently but progressing more slowly than planned.
This could indicate resource shortages, delayed approvals, procurement issues, design changes, or other schedule constraints.
Saving money is not necessarily positive if the project is unable to achieve required milestones.
CV and SV vs CPI and SPI
Variance values tell you the difference, while performance indices show efficiency.
1. Cost Performance Index (CPI)
The formula is:
CPI = EV ÷ AC
A CPI of:
- Greater than 1.0: Favorable cost efficiency.
- 1.0: Cost performance is on target.
- Less than 1.0: Unfavorable cost efficiency.
2. Schedule Performance Index (SPI)
The formula is:
SPI = EV ÷ PV
A SPI of:
- Greater than 1.0: More work has been earned than planned.
- 1.0: Progress is aligned with the plan.
- Less than 1.0: Less work has been earned than planned.
PMI guidance identifies CPI and SPI as complementary measures to CV and SV.
For example, the earlier project has:
CPI = $80,000 ÷ $90,000 = 0.89
SPI = $80,000 ÷ $100,000 = 0.80
This indicates unfavorable cost efficiency and progress below the planned level.
Why CV and SV Matter in Project Controls
Variance analysis is not simply about producing monthly reports. It helps project teams understand where performance is moving away from the baseline.
For professionals working with Integrated Project Controls, CV and SV can contribute to a broader performance-management process involving:
- Cost monitoring
- Schedule monitoring
- Earned value analysis
- Forecasting
- Progress measurement
- Risk analysis
- Corrective action
- Management reporting
The Project Controls Institute (PCI) emphasizes integrated project controls capabilities that connect planning, cost, schedule, risk, forecasting, and performance management. This makes variance analysis an important practical skill for project controls professionals.
The most valuable question after identifying a variance is not simply “What is the variance?” It is “Why did the variance occur, and what should we do next?”
Common Mistakes When Interpreting CV and SV
1. Looking at CV or SV in Isolation
One favorable indicator does not automatically mean the project is healthy. Always consider cost, schedule, scope, risk, and forecast information together.
2. Treating SV as Actual Days of Delay
Traditional SV is calculated using EV and PV, so it is expressed in the same value units used for those measures. It should not automatically be interpreted as “10 days late,” for example. Time-based earned schedule methods can provide a more direct view of schedule delay.
3. Ignoring the Trend
A single month's variance may not tell the whole story. Tracking CV, SV, CPI, and SPI over several reporting periods can reveal whether performance is improving or deteriorating.
4. Focusing Only on the Number
A variance is a signal for investigation, not a diagnosis. The team still needs to identify the underlying cause and determine an appropriate response.
How to Use CV and SV for Better Project Decisions
A practical variance-review process can follow these steps:
- Calculate CV and SV using reliable PV, EV, and AC data.
- Review CPI and SPI to understand performance efficiency.
- Compare current and cumulative results to identify trends.
- Investigate significant variances and identify their root causes.
- Assess the impact on cost, schedule, scope, risk, and forecast.
- Develop corrective or preventive actions.
- Monitor the next reporting cycle to determine whether the action worked.
This approach turns EVM from a reporting exercise into a decision-support process.
Final Takeaway
Cost Variance and Schedule Variance answer two different but connected project-performance questions. CV shows whether the cost of completed work is favorable or unfavorable, while SV shows whether the amount of work completed is ahead of or behind the planned progress. For professionals developing project controls qualification and practical project-management capability, understanding these measures is essential because they connect baseline planning with actual project performance. The Project Controls Institute (PCI) provides a broader integrated project-controls perspective in which cost, schedule, risk, forecasting, and performance information support better project decisions.
When reviewing project performance, do not stop at calculating the variance. Look at the trend, investigate the root cause, assess the impact, and determine what action is needed. Used correctly, CV and SV can help project teams move from simply reporting project problems to identifying them early enough to manage them.
Frequently Asked Questions
Q1. What is the formula for Cost Variance?
Cost Variance is calculated as CV = EV − AC. A positive value is generally favorable, while a negative value indicates unfavorable cost performance.
Q2. What is the formula for Schedule Variance?
Schedule Variance is calculated as SV = EV − PV. A positive value indicates that more work has been earned than planned, while a negative value indicates less work has been earned than planned.
Q3. What does a negative Cost Variance mean?
A negative CV means the actual cost of the completed work is greater than its earned budgeted value. In simple terms, the project is experiencing unfavorable cost performance.
Q4. What does a negative Schedule Variance mean?
A negative SV means the project has earned less value than was planned by the status date. It indicates unfavorable progress against the schedule baseline.
Q5. Can a project have a positive CV and negative SV?
Yes. A project can be under budget for the work performed while still completing less work than planned. This is why cost and schedule performance should be reviewed separately and together.
Q6. What is the difference between CV and CPI?
CV measures the absolute variance between earned value and actual cost. CPI measures cost efficiency by dividing earned value by actual cost.
Q7. What is the difference between SV and SPI?
SV measures the difference between earned value and planned value. SPI measures the ratio of earned value to planned value and indicates relative progress efficiency.
Q8. Are CV and SV important for project controls professionals?
Yes. Understanding CV and SV helps project controls professionals monitor performance, identify deviations from baseline expectations, investigate root causes, and support forecasting and corrective action.
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