Triangular Estimate
This is the simplest way to turn three guesses into one estimate. Just like the PERT method, you collect three numbers: "O" the optimistic estimate (everything goes perfectly), "M" the most likely estimate (a normal day), and "P" the pessimistic estimate (things go wrong). The difference here is how you blend them.
To calculate it, you simply add all three numbers together and divide by three — a plain average that treats each estimate as equally important. No number gets extra weight.
Because it gives equal say to the best and worst cases, this method is more sensitive to extreme values than PERT. If your pessimistic guess is very large, it will pull the estimate noticeably higher. Project managers use this when they want a quick, easy-to-explain estimate, or when they genuinely believe all three outcomes are about equally possible and don't want to favor the most likely one.
Think of it like averaging three friends' guesses for how long a road trip will take, where you trust each friend exactly the same amount — even the one who always assumes the worst traffic.
Using the same webpage task: Optimistic = 4 days, Most Likely = 6 days, Pessimistic = 14 days. Apply the formula: E = (4 + 6 + 14) / 3 = 24 / 3 = 8 days. Your estimate is 8 days. Compare this to the PERT result of 7 days for the same numbers — the triangular estimate came out higher because it let the large pessimistic value (14) have just as much influence as the realistic value (6).
Every PMP formula explained free — plus worked examples and practice in PMP Math, and full timed mocks in the simulator.