🧮 PMP Formulas
Study Notes — Formulas Page | ClearPMPExam.com
How to use this page: Learn each formula, what it means in plain English, and the worked example. In the exam, always calculate EV first. For PERT, always multiply Most Likely by 4 first. For channels, always divide by 2 last.
1. Earned Value Management — Core Terms First
Before any formula, you need to understand the four inputs. Every EVM calculation starts here.
In EVERY EVM question: Step 1 = Calculate EV first. EV = % work done × BAC. EV appears in both CPI (EV÷AC) and SPI (EV÷PV). If EV is wrong, everything else is wrong. Never skip this step.
2. All 8 EVM Formulas
| Formula | Calculation | If positive / >1 | If negative / <1 |
|---|---|---|---|
| CV Cost Variance |
EV − AC | Under budget ✅ | Over budget ❌ |
| SV Schedule Variance |
EV − PV | Ahead of schedule ✅ | Behind schedule ❌ |
| CPI Cost Performance Index |
EV ÷ AC | >1 = under budget, efficient ✅ | <1 = over budget ❌ |
| SPI Schedule Performance Index |
EV ÷ PV | >1 = ahead of schedule ✅ | <1 = behind schedule ❌ |
| EAC Estimate at Completion |
BAC ÷ CPI | Expected final cost of the project. Most common EAC formula in exam. | |
| ETC Estimate to Complete |
EAC − AC | Money still needed to finish the project from today. | |
| VAC Variance at Completion |
BAC − EAC | Positive = will finish under budget ✅ | Negative = will finish over budget ❌ |
| TCPI To Complete Performance Index |
(BAC − EV) ÷ (BAC − AC) | >1 = must work more efficiently than current. <1 = can afford to slow down. | |
For both CPI and SPI: greater than 1 = good news. Less than 1 = bad news. Equal to 1 = perfect. Same rule for both — no exceptions.
3. PERT Formula — Three-Point Estimation
E = (3 + 4×6 + 15) ÷ 6 = (3 + 24 + 15) ÷ 6 = 42 ÷ 6 = 7 days
Confidence Intervals — Sigma Rules
Step 1: Multiply M by 4 first. Step 2: Add O + result + P. Step 3: Divide by 6. Never divide first. Never forget the ×4 on M. For SD: always P minus O (bigger minus smaller), then divide by 6.
4. Communication Channels Formula
Add 2 more (12 people): 12 × 11 ÷ 2 = 66 channels
Adding 2 people created 21 new channels
Pre-calculated Reference — Most Common Exam Numbers
Type 1: “How many channels for a team of 10?” → Single calculation: 10×9÷2 = 45.
Type 2: “Team grew from 5 to 8. How many NEW channels were added?” → Two calculations: 8×7÷2 = 28 minus 5×4÷2 = 10 → Answer: 18 new channels. Always calculate both sizes and subtract.
5. Expected Monetary Value (EMV)
🧮 Worked Example — Campaign Project
6. Float / Slack Formulas
LF = Late Finish | EF = Early Finish | LS = Late Start | ES = Early Start. The exam usually gives you these values directly in a network diagram question rather than asking you to calculate them from scratch.
7. Full EVM Worked Example — Step by Step
The exam always gives you a scenario. Here is how to solve it using the exact step-by-step method.
🧮 Pharma App Launch Project
BAC = ₹1,00,000 | Total Duration = 10 months
Time elapsed = 5 months | Work completed = 45% | AC = ₹42,000
8. All Formulas — One Page Reference
Every formula you need for the PMP exam. Bookmark this page for your last revision session.
| Formula Name | Calculation | Plain English Meaning | Topic |
|---|---|---|---|
| EV (Earned Value) | % done × BAC | Value of work actually completed | EVM |
| PV (Planned Value) | % planned × BAC | Value of work planned to be done by now | EVM |
| CV (Cost Variance) | EV − AC | +ve = under budget, −ve = over budget | EVM |
| SV (Schedule Variance) | EV − PV | +ve = ahead, −ve = behind schedule | EVM |
| CPI (Cost Performance Index) | EV ÷ AC | >1 = under budget, <1 = over budget | EVM |
| SPI (Schedule Performance Index) | EV ÷ PV | >1 = ahead, <1 = behind schedule | EVM |
| EAC (Estimate at Completion) | BAC ÷ CPI | Expected final project cost | EVM |
| ETC (Estimate to Complete) | EAC − AC | Money still needed to finish | EVM |
| VAC (Variance at Completion) | BAC − EAC | +ve = finish under budget, −ve = overrun | EVM |
| TCPI | (BAC − EV) ÷ (BAC − AC) | Efficiency needed in remaining work | EVM |
| PERT Expected Duration | (O + 4M + P) ÷ 6 | Weighted average of 3 estimates | Schedule |
| Standard Deviation | (P − O) ÷ 6 | Spread of uncertainty in PERT estimate | Schedule |
| ±1 Sigma Confidence | E ± 1 SD | 68% probability task finishes in this range | Schedule |
| ±2 Sigma Confidence | E ± 2 SD | 95% probability task finishes in this range | Schedule |
| ±3 Sigma Confidence | E ± 3 SD | 99.7% probability task finishes in this range | Schedule |
| Communication Channels | n × (n − 1) ÷ 2 | Number of channels for n team members | Communication |
| New Channels Added | New channels − Old channels | When team size changes, subtract old from new | Communication |
| EMV (Expected Monetary Value) | Probability × Impact | Average financial outcome of a risk. Threats = −ve, Opportunities = +ve | Risk |
| Total Float | LF − EF or LS − ES | Delay without delaying the project end date. Zero on critical path. | Schedule |
| Free Float | ES(next) − EF(current) | Delay without delaying the next activity | Schedule |
| Parametric Estimating | Rate × Quantity | Cost or duration = unit rate × number of units | Schedule / Cost |
| Cost Baseline | Work costs + Contingency Reserve | Approved budget excluding Management Reserve | Cost |
| Total Project Funding | Cost Baseline + Management Reserve | Full funding including unknown risk buffer | Cost |
✅ Formulas page complete. Every formula in one place — EVM, PERT, Communication Channels, EMV, Float, and all budget calculations. Use this as your last-minute revision sheet the night before the exam.