Schedule variance vs cost variance is a comparison between two earned value management metrics. Schedule variance measures whether the program has accomplished more or less work than planned. Cost variance measures whether the accomplished work cost more or less than its budgeted value.
The distinction matters because a program can run behind schedule while remaining under cost, or run ahead of schedule while exceeding its budget. Neither metric explains the full condition by itself. Program managers, Control Account Managers (CAMs) and analysts should evaluate both variances, then reconcile them with the Integrated Master Schedule (IMS), actual costs and forecast.
Schedule variance vs cost variance: the direct comparison
Earned Value Management (EVM) uses three core data elements:
- Planned Value (PV): The time-phased budget for work scheduled through the status date. The legacy term is Budgeted Cost for Work Scheduled (BCWS).
- Earned Value (EV): The budgeted value of work actually accomplished through the status date. The legacy term is Budgeted Cost for Work Performed (BCWP).
- Actual Cost (AC): The recorded cost of accomplishing that work. The legacy term is Actual Cost of Work Performed (ACWP).
For a more detailed explanation of the terminology, see BCWS, BCWP and ACWP vs PV, EV and AC.
The two variance formulas use EV as their common point of comparison:
- Schedule Variance (SV) = EV − PV
- Cost Variance (CV) = EV − AC
Therefore, SV asks, “Did we accomplish the amount of work planned by the status date?” CV asks, “Did the accomplished work cost what we budgeted for it?” The NASA Project Planning and Control Handbook uses these formulas and cautions that SV is an indicator rather than a direct measure of time or criticality.
How to interpret schedule variance
Schedule variance compares earned progress with the baseline value of work scheduled through the reporting cutoff.
- Positive SV: The program earned more value than planned through the status date.
- Zero SV: Earned value equals planned value at the selected level.
- Negative SV: The program earned less value than planned through the status date.
For example, if PV is $5 million and EV is $4 million, SV equals negative $1 million. The program has not earned $1 million of the work value planned through the cutoff.
However, the program is not necessarily “$1 million late.” Traditional SV is expressed in budget units, usually dollars or labor hours. It does not state that a milestone will finish a specific number of days late.
Schedule variance is not a critical path calculation
A negative SV can come from critical, near-critical or high-float work. Likewise, a positive summary-level SV can coexist with delays on the program’s driving path. Favorable performance in one control account may offset an unfavorable variance in another.
Therefore, analysts should reconcile SV with the logic-driven IMS. Review driving predecessors, total float, missed baseline dates, forecast milestone movement and the current critical path. The Department of Energy also advises analysts to combine earned value metrics with network schedule information because SV alone does not reveal critical path status.
Use the same reporting cutoff when comparing the systems. The IMS status date should align with the EVM accounting calendar and reporting period. Otherwise, the schedule and cost system may describe different points in time.
How to interpret cost variance
Cost variance compares the budgeted value of completed work with the actual cost incurred for that same work.
- Positive CV: The accomplished work cost less than its budgeted value.
- Zero CV: Actual cost equals the budgeted value of completed work.
- Negative CV: The accomplished work cost more than its budgeted value.
Suppose a team earned $4 million of value but recorded $4.5 million in actual costs. CV equals negative $500,000. The team spent $500,000 more than the budgeted value of its completed work.
Cost variance often has stronger implications for the final cost forecast than traditional SV has for the completion date. A cumulative cost overrun does not disappear merely because the remaining work finishes on time. The CAM must determine whether the variance reflects a one-time event, a recurring efficiency problem or a condition that will affect the remaining estimate to complete.
That analysis should connect CV to the current Estimate to Complete (ETC) and Estimate at Completion (EAC). A favorable current-period CV does not automatically support an underrun forecast. Meanwhile, a negative cumulative CV may require an EAC increase if the same drivers will continue.
What the four SV and CV combinations reveal
Comparing the signs of both variances provides a useful starting point for analysis.
Negative SV and negative CV
The program has completed less work than planned and spent more than the budgeted value of that work. This is the clearest adverse combination. Possible causes include low labor productivity, technical rework, supplier problems, late material or underestimated complexity.
Negative SV and positive CV
The program is behind its baseline accomplishment plan but reports favorable cost performance. This condition requires careful review. The apparent underrun may result from delayed hiring, late invoices, missing accruals or work that has not started.
Therefore, “under cost” may not be good news. The program may simply have deferred both the work and its associated cost.
Positive SV and negative CV
The program has earned more value than planned but spent more than the budgeted value of that work. Management may have added shifts, authorized overtime or used more expensive resources to accelerate progress.
This trade may support an important delivery objective. However, the team should determine whether the acceleration was planned, affordable and reflected in the EAC.
Positive SV and positive CV
The program appears ahead of its accomplishment plan and under the budgeted cost of completed work. Although favorable, the result still deserves validation. Analysts should check for premature earned value, inaccurate actual costs, weak objective completion criteria or summary-level masking.
Fictional program example
Consider the fictional Falcon Ridge sensor development program. At the end of the June reporting period, the program reports:
- PV of $10 million
- EV of $8 million
- AC of $9 million
The calculations are:
- SV = $8 million − $10 million = negative $2 million
- CV = $8 million − $9 million = negative $1 million
The program earned $2 million less value than planned. In addition, it spent $1 million more than the budgeted value of the work accomplished.
The percentages add scale:
- SV% = SV ÷ PV = −20%
- CV% = CV ÷ EV = −12.5%
The equivalent performance indices are Schedule Performance Index (SPI) of 0.80 and Cost Performance Index (CPI) of approximately 0.89. See CPI vs SPI for a focused explanation of those ratios.
Next, the program-controls team reviews the IMS. It finds that late environmental qualification testing is driving a forecast slip to the design certification milestone. Meanwhile, engineering rework caused the adverse CV. The schedule and cost variances have related technical origins, but they measure different consequences.
A useful variance narrative would identify the failed test condition as the root cause, describe the certification milestone impact, quantify the rework cost and explain the corrective action. It would also address whether the remaining test and redesign effort has been incorporated into the forecast and ETC.
How practitioners should analyze SV and CV
1. Start below the summary level
Program-level variances can hide opposing conditions. Review control accounts, work breakdown structure elements, work packages and elements of cost. Look for offsetting positive and negative variances that disappear during rollup.
2. Separate current and cumulative performance
Current-period variance helps identify what changed this month. Cumulative variance shows the net performance since the baseline began. A favorable monthly result may represent genuine recovery, or it may only reflect a quiet accounting period.
3. Validate the underlying data
Check whether earned value matches objective accomplishment. Also confirm that actual costs align with the same work and accounting period. Missing accruals, delayed supplier invoices and incorrect progress can distort CV.
For SV, confirm that the performance measurement baseline and IMS use consistent work scope and dates. Poor schedule status can undermine the comparison. The process described in how to status an Integrated Master Schedule helps establish a reliable reporting cutoff.
4. Connect variance to forecast impact
A variance narrative should go beyond restating the number. Identify the root cause, explain the effect on downstream work and quantify the forecast impact. Then assign a corrective action, responsible owner and expected completion date.
The Department of Energy’s EVMS Variance Analysis Quality Checklist emphasizes root cause, schedule impact, EAC impact and corrective-action tracking. Those elements provide a strong model even when a program uses different contractual thresholds or report formats.
Common mistakes when comparing SV and CV
- Translating SV dollars directly into days: SV measures accomplishment in budget terms. Use the network schedule to determine calendar impact.
- Assuming positive variance is automatically favorable: Delayed work, missing actuals or premature progress can create misleading results.
- Ignoring the status date: Schedule, earned value and actual cost data must use compatible cutoff periods.
- Using summary metrics without drilling down: Positive and negative work-package variances can offset each other.
- Confusing cost variance with funding status: CV compares EV with AC. It does not measure available funding, cash flow or contract funding limits.
- Treating SV as a completion-date forecast: Traditional cumulative SV normally converges toward zero when all budgeted work has been earned, even if the program finishes late.
- Applying a universal variance threshold: Reporting thresholds may depend on the contract, data item, agency, program procedures or approved EVMS description.
Contractual requirements versus management practice
The SV and CV formulas are standard EVM calculations. However, the formulas alone do not establish whether a contract must use an Earned Value Management System (EVMS), submit monthly data or prepare a formal variance narrative.
FAR Subpart 34.2 provides the federal EVMS framework. For applicable DoD contracts, the solicitation and contract may include DFARS 252.234-7002 and associated data requirements. Application can vary by contract type, value, acquisition strategy, agency procedures and approved tailoring.
Therefore, teams should read the actual contract, Contract Data Requirements List, applicable data item description and approved EVMS system description. A recommended management practice should not be presented as a contractual requirement unless the governing documents make it one.
Schedule and cost variance in Microsoft Project
Microsoft Project calculates earned value SV as BCWP minus BCWS and CV as BCWP minus ACWP. Its SV field documentation also confirms that SV appears in cost terms rather than calendar days.
Do not confuse the earned value SV field with baseline start or finish variance fields. Those fields compare schedule dates and durations. They support schedule analysis, while earned value SV compares the budgeted value of accomplished and planned work.
Frequently asked questions
Can a project have a favorable CV and still be in trouble?
Yes. A positive CV may result from delayed work, missing actual costs or unfilled positions. Review schedule status, accruals and the remaining forecast before concluding that the program will underrun.
Does negative SV prove the critical path is late?
No. Negative SV shows that less budgeted work was accomplished than planned. Only network analysis can determine whether that condition affects the critical path, contractual milestones or completion date.
Which metric is more important?
Neither should be used alone. SV provides an accomplishment indicator, while CV measures cost efficiency for completed work. Together with CPI, SPI, forecast dates, total float and EAC, they support an integrated view of program performance.
What should a good variance explanation include?
It should identify the root cause, quantify the variance, describe cost and schedule impacts, explain the effect on the forecast and define corrective actions. It should also distinguish between current-period events and conditions that will continue through completion.
The practical takeaway
Schedule variance compares EV with PV. Cost variance compares EV with AC. That common use of earned value allows the two metrics to describe different dimensions of the same completed work.
However, the numbers are only the start of the analysis. Reconcile SV with the logic-driven IMS, and connect CV to actual-cost integrity and the EAC. Then explain the root cause, impact and corrective action at the level where management can act.