Project timeline estimator
Give best, likely and worst-case weeks for each phase and get an expected finish date and a safer one to promise.
Free, runs in your browser, no sign-up. Updated 2026-10-25.
Result
Expected 22.7 weeks (about 85% likely within 25, 95% within 26.4). From 25 Oct 2026: likely done 2 Apr 2027, safe date 18 Apr 2027.
- About 85% likely within
- 25 weeks
- About 95% likely within
- 26.4 weeks
- Everything goes right
- 14 weeks
- Everything goes wrong
- 38 weeks
| Phase | Best | Likely | Worst | Expected | Spread (SD) |
|---|---|---|---|---|---|
| Discovery and scope | 1 | 2 | 4 | 2.2 | 0.5 |
| Design and clickable prototype | 2 | 3 | 5 | 3.2 | 0.5 |
| Build | 8 | 12 | 20 | 12.7 | 2 |
| Testing and fixes | 2 | 3 | 6 | 3.3 | 0.67 |
| Launch and handover | 1 | 1 | 3 | 1.3 | 0.33 |
Phases run one after another. The percentages assume the phases vary independently, a normal approximation.
Send this timeline to OceanLab
Opens an email to OceanLab with this result and a link to your inputs. Nothing is sent until you press send, and there is no sign-up.
How this is calculated
Each phase uses the PERT three-point formula: expected = (best + 4 × likely + worst) ÷ 6, and spread (standard deviation) = (worst − best) ÷ 6.
Phases run one after another, so the expected total is the sum of the phases. The spread of the total is the square root of the summed squares, assuming phases vary independently.
The 85% and 95% figures add 1.04 and 1.645 standard deviations, a normal approximation. Dates count calendar weeks from the start date.
The default weeks are an example for a first product release, not a benchmark.
Questions about this tool
Which date should I promise?
The 85% date is a common choice: likely enough to keep, without padding every phase. The expected date is a coin toss.
Why do worst cases matter so much?
Overruns are bigger than early finishes, so the worst case pulls the expected value up more than the best case pulls it down.
Can phases overlap?
This model runs them in sequence. If design and build overlap, shorten the build phase by the overlap.
Is anything I enter sent anywhere?
No. The tool runs in your browser and there is no sign-up. Nothing leaves the page unless you choose to email your result to OceanLab.
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