Cost Variance Calculator
EVM AnalysisAdvanced cost variance analysis with CPI metrics and professional earned value management
EV - AC: Measure cost performance variance
Cost Performance Index for efficiency tracking
Estimate at Completion calculations
Comprehensive budget variance monitoring
Cost Performance Metrics
Budgeted cost of work scheduled
Budgeted cost of work performed
Actual cost of work performed
Total planned budget for the project
What is Cost Variance (CV)?
Cost Variance is the heartbeat metric of earned value management. It tells you, in cold hard dollars, whether your project is spending more or less than it should be at this point in time. A positive CV means you are under budget -- you are getting more value for your money than planned. A negative CV means you are over budget, and every dollar of negative variance is money that has to come from somewhere: contingency reserves, management reserves, or your sponsor's patience.
What makes CV genuinely useful compared to simply looking at "budget spent versus budget planned" is that it accounts for actual work completed. If you have spent 80% of your budget but only completed 60% of the work, the raw budget comparison might look acceptable. CV exposes the real problem: you are paying for 100% but earning only 60%. This is why CV is paired with its cousin, the Cost Performance Index (CPI), which expresses the same relationship as a ratio that is easier to trend over time.
In the PMBOK Guide, Cost Variance is a core output of the Control Costs process within Project Cost Management. It is calculated at the work package level and can be rolled up to control account and project levels. Regular CV tracking -- weekly or biweekly at minimum -- enables early detection of cost overruns and gives the project manager time to implement corrective actions before the variance becomes unrecoverable.
Cost Variance Formula Explained
EV (Earned Value) is the budgeted cost of work actually performed. If you planned to spend $100,000 on a deliverable and you have completed 60% of it, your EV is $60,000 regardless of what you actually spent. AC (Actual Cost) is exactly what it sounds like -- the real money spent on that work. If AC is $75,000, then CV = $60,000 - $75,000 = -$15,000 (you are $15K over budget) and CPI = $60,000 / $75,000 = 0.80 (you are getting 80 cents of value for every dollar spent).
The relationship between CV and CPI is straightforward but powerful. CV gives you the dollar magnitude of the problem; CPI gives you the efficiency rate. CPI is especially valuable for forecasting. If your current CPI is 0.80, you can project that the final project cost will be BAC / 0.80 -- a 25% overrun. This CPI-based Estimate at Completion formula is one of the most frequently tested on the PMP exam.
Step-by-Step Guide to Cost Variance Analysis
Establish the Planned Value (PV) by distributing the BAC across the project timeline. At any reporting date, PV represents how much work should have been completed in budget terms.
Measure the Earned Value (EV) by assessing the percentage of work actually completed for each work package and multiplying by the work package budget. Use objective measurement criteria whenever possible.
Collect the Actual Cost (AC) from your accounting or time-tracking system. Ensure all costs are captured including labor, materials, and overhead allocations for the reporting period.
Calculate CV = EV - AC and CPI = EV / AC. A positive CV and CPI above 1.0 indicate under-budget performance. A negative CV and CPI below 1.0 indicate over-budget performance requiring corrective action.
Investigate root causes of any significant variance, document findings, and implement corrective actions. Update your EAC forecast and communicate the revised budget outlook to stakeholders through change control.
Real-World Cost Variance Example
Scenario: Commercial Building Renovation Project at 40% Complete
Budget at Completion (BAC): $2,000,000
Planned Value at reporting date (PV): $800,000
Work actually completed (Earned Value): $700,000 (35% of total scope)
Actual Cost incurred to date: $850,000
CV = $700,000 - $850,000 = -$150,000 (over budget)
CPI = $700,000 / $850,000 = 0.82
EAC = $2,000,000 / 0.82 = $2,439,024
Result: The project is $150K over budget and running at 82% cost efficiency. At this rate, the final cost will be approximately $2.44M -- a projected $439K overrun that needs immediate corrective action.
Common Mistakes to Avoid
- Confusing CV with SV -- Cost Variance (EV - AC) measures budget performance. Schedule Variance (EV - PV) measures time performance. Both are essential but answer different questions.
- Using only absolute dollars -- A $50K variance on a $1M project is concerning. The same $50K on a $10M project is noise. Always consider CV as a percentage and alongside CPI for context.
- Inaccurate EV measurement -- If your work completion percentages are guesses, your CV will be meaningless. Use milestone-based or weighted criteria to measure EV objectively.
- Delayed cost reporting -- CV is only useful for corrective action if AC data is timely. Lagging cost data by a month makes variance analysis reactive rather than proactive.
- Ignoring the trend -- A single negative CV might be an anomaly. Three consecutive negative CVs with declining CPI signal a systemic problem requiring structural changes, not just a quick fix.
- Focusing only on negative variances -- Large positive variances can indicate scope gaps, under-resourcing, or overly conservative estimates. Investigate them too.
PMP Exam Tips for Cost Variance
Cost Variance is one of the highest-yield topics on the PMP exam. Expect multiple questions that give you EV and AC and ask for CV, or give you EV and AC and ask for CPI. The math is simple subtraction and division, but the exam tests your interpretation skills. Know these rules cold: CV greater than zero is good (under budget), CV less than zero is bad (over budget). CPI greater than 1.0 is good, CPI less than 1.0 is bad. A CPI of 0.85 means you are earning 85 cents for every dollar spent.
The exam also frequently tests EAC calculations derived from CV data. The three EAC formulas you must know are: EAC = BAC / CPI (assuming current efficiency continues), EAC = AC + (BAC - EV) (assuming future work returns to planned efficiency), and EAC = AC + [(BAC - EV) / (CPI x SPI)] (when both cost and schedule performance affect future work). The PMBOK Guide presents these in the Control Costs process. Pay attention to the question wording to determine which formula to apply -- phrases like "current trend continues" point to the CPI-based formula, while "original estimate is valid" points to the second approach.