Welcome to the complete how-to guide for PMP exam formulas. In the table below, you will see how and why each formula is used. I have posted the most common formulas used on the exam. There are however, other formulas, but most of which were used on previous PMP exams and are no longer used.

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**(O + 4M + P) / 6**

O = Optimistic

M = Most likely estimate

P = Pessimistic estimate

*Commonly used and preferred on PMP

**(P + ML + O) / 3**

O = Optimistic

ML = Most likely P = Pessimistic estimate

*Estimate duration of a scheduled activity

**(P – O) / 6**

O = Optimistic

P = Pessimistic estimate

*Rough estimate for standard deviation

**N (n-1) /2**

*number of communication channels.

**SPI = EV / PV**

EV = Earned Value

PV = Planned Value

= 1 is great – you are progressing as planned

> 1 progressing faster than planned

< 1 not so good – progressing slowly

**CPI = EV / AC **

EV = Earned value, AC = Actual cost

= 1 is good. 1 for 1 spend.

> 1 is better. You are getting >1 for every $1

< 1 not so good. You are getting <$1 for every $1

**SV = EV – PV **

EV = Earned value,

PV = Planned Value

- Positive = ahead of schedule
- Neutral = on schedule
- Negative = behind schedule

**CV = EV – AC **

EV = Earned value

AC = Actual cost

- Negative = over budget (spent too much)
- Positive = under budget

**EAC = AC + BAC – EV (Estimate time to completion)**

AC = Actual Cost

BAC = Budget at Completion

EV = Earned Value

*The variance is caused by a one-time event. Most likely won’t reoccur.

**EAC = BAC / CPI (Estimate time to completion)**

BAC = Budget at Completion

CPI = Cost performance index

*If CPI remains the same (no variances) until the end of the project.

or

AC + (BAC – EV) – calculates actual cost to date plus remaining work

**EAC = AC + (BAC – EV) / (CPI*SPI)**

AC = Actual Cost

BAC = Budget at completion

EV = Earned Value

CPI = Cost performance index

SPI = Schedule performance index

Used when you are presented with all the values for each one. You probably won’t see one of these questions on the exam.

**TCPI = (BAC – EV) / (BAC – AC)**

TCPI = Remaining work/ remaining funds

<1 under budget

=1 on budget

>1 over budget

**ETC = EAC – AC**

EAC = Estimate at completion

AC = Actual cost

*Used to determine how much it will cost to finish project. How much more will you spend to finish.

**VAC = BAC – EAC **

BAC = Budget at completion

EAC = Estimate at completion

<0 under budget

=0 on budget

>0 over budget

* Helps you determine if you will be over or under budget on completion.

*The best project has the higher NPV = (better project)

Positive NPV is good, negative NPV is bad.

**P x I **

P = Probability, I = Impact

*Good for ranking risks

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Now that you have learned how to use the PMP exam formulas, check out some free practice exam questions to put your formulas to work. The PMP exam is a difficult exam, but with the right preparation, you can definitely pass it first time around. If you are still unsure about whether or not you are ready for the exam, check out this article Are You Ready To Take The PMP Exam?

For more articles on project management certifications, check out our Get-Certified Articles page. For videos on interview preparation, check out our series English Interviews!