When I sat for the PMP exam on October 10, 2026, I expected to spend part of the morning doing earned value math. I didn't calculate a single formula. Instead, question after question gave me a number such as a CPI, an SPI, a float value or an expected monetary value, and asked what it meant or what I should do next.
That doesn't mean you can skip the formulas. You still need to know them cold, because you can't interpret a number you don't understand. But it changes how you should study them. This guide covers the formulas that matter most and, more importantly, how to read each result the way the exam expects.
Why interpretation matters more than calculation
The PMP exam is built around scenarios. A typical question describes a project situation, gives you one or two metrics, and asks for the best next action. If you know that a CPI of 0.85 means you're getting 85 cents of value for every dollar spent, you can rule out half the answers immediately. If you only memorized "CPI = EV / AC", you'll lose time working backward.
So for each formula below, learn three things: what goes in, what comes out, and what the result tells you to do.
Earned value formulas
| Formula | Calculation | How to read it |
|---|---|---|
| Cost variance (CV) | EV − AC | Negative means over budget |
| Schedule variance (SV) | EV − PV | Negative means behind schedule |
| Cost performance index (CPI) | EV / AC | Below 1 means over budget |
| Schedule performance index (SPI) | EV / PV | Below 1 means behind schedule |
| Estimate at completion (EAC), typical | BAC / CPI | Assumes the current cost trend continues |
| EAC, atypical | AC + (BAC − EV) | Assumes the overrun was a one-time event |
| Estimate to complete (ETC) | EAC − AC | Money still needed to finish |
| Variance at completion (VAC) | BAC − EAC | Negative means an overrun is expected |
| To-complete performance index (TCPI) | (BAC − EV) / (BAC − AC) | Above 1 means the team must work more efficiently than planned |
Example: CPI 0.85, SPI 1.05
The work is slightly ahead of schedule but over budget. A strong answer usually involves finding out why costs are high, such as overtime or extra resources used to get ahead, before choosing a corrective action. Recommending cancellation or ignoring the numbers is almost never right.
Example: TCPI 1.25
To finish within the original budget, the remaining work must be done 25% more efficiently than planned. That's a warning sign. Expect the right answer to involve reviewing the forecast with stakeholders or revising the EAC, not simply telling the team to work harder.
Schedule and risk formulas
| Formula | Calculation | How to read it |
|---|---|---|
| PERT (beta) estimate | (O + 4M + P) / 6 | A weighted average that favors the most likely value |
| Triangular estimate | (O + M + P) / 3 | A simple average of the three points |
| Standard deviation (beta) | (P − O) / 6 | How spread out the estimate is |
| Total float | LS − ES or LF − EF | Zero on the critical path |
| Expected monetary value (EMV) | Probability × Impact | Threats are negative, opportunities positive |
| Communication channels | n(n − 1) / 2 | n is the number of people |
Example: a critical path activity slips 2 days
Critical path activities have zero total float, so the project finish date slips by 2 days unless you compress the schedule. Answers claiming "no effect because other paths have float" are traps.
Agile and value metrics
About half the exam reflects agile or hybrid approaches, so expect velocity and value questions too. Velocity forecast = remaining story points ÷ average velocity, which gives the number of iterations left. For business cases, a benefit-cost ratio above 1 means the benefits outweigh the costs, and higher NPV or IRR is better. Ignore sunk costs when choosing between options.
How to study formulas for the 2026 exam
- Memorize them first. Write the full list from memory until you can do it in under two minutes.
- Then practice reading results. For each formula, quiz yourself: "If this number is above 1, what does it mean? If it's below 1?"
- Practice scenario questions. Use questions that hand you a metric and ask for the next action, not just the math.
- Write your formula sheet on exam day. Many candidates write the formulas on their scratch paper or whiteboard after the tutorial ends, so they can focus on interpretation during the exam.
Practice with real scenario questions
PMP Sprint tags its formula questions as Interpret questions because they work exactly like the ones I saw on exam day: you get the numbers and decide what they mean. You can try 10 free PMP practice questions right now, with no signup, including two Interpret questions on CPI and the critical path.
When you're ready for the full set, the PMP Sprint bundle includes 352 practice questions, timed mock exams scored by domain, and a formula table that shows what every result tells you.
Frequently asked questions
Do you have to calculate formulas on the PMP exam?
You may see some calculation questions, but on my exam every formula question gave me the result and asked what it meant or what to do next. Prepare for both, and put most of your practice into interpretation.
Which PMP formulas are most important?
Earned value (CV, SV, CPI, SPI, EAC, ETC, VAC, TCPI), PERT estimates, float, EMV and communication channels come up most often in study materials. Know what a result above or below 1 means for every index.
Can I bring a formula sheet into the PMP exam?
No, but you can usually write formulas down on the scratch paper or whiteboard you're given during the exam. Check PMI's current exam rules before your test date.
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