Estimate project duration and cost using three-point estimation.
The PERT weighting produces an expected value above the most likely estimate whenever the pessimistic tail is longer than the optimistic one, which it almost always is. Quoting at 85 per cent confidence adds roughly one standard deviation. Quoting the most likely estimate means missing the deadline about half the time, which is why commercial quotes are made at a stated confidence level instead.
Project Estimation
PERT expected = (optimistic + 4 × most likely + pessimistic) ÷ 6
PERT expected = (optimistic + 4 × most likely + pessimistic) ÷ 6 The PERT weighting produces an expected value above the most likely estimate whenever the pessimistic tail is longer than the optimistic one, which it almost always is. Quoting at 85 per cent confidence adds roughly one standard deviation.
Quoting the most likely estimate means missing the deadline about half the time, which is why commercial quotes are made at a stated confidence level instead.
This calculator takes 5 inputs: Optimistic estimate, Most likely estimate, Pessimistic estimate, Hourly rate, Confidence level. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.