When will your project really finish?
Upload a Microsoft Project or Primavera P6 schedule and Onplana's free Schedule Risk Analyzer runs it 2,000 times with every task's duration varied, then tells you the date you finish by half the time (P50), 80% of the time (P80) and 90% of the time (P90), and the chance of hitting the date in your file.
From one finish date to a range you can commit to
Today
- Read the finish date off the Gantt, which assumes every task takes exactly its planned duration.
- Add a buffer by feel, or copy the task list into Excel and build a simulation by hand.
- Or buy and learn a risk add-on before anyone asks how sure the date is.
With this tool
- Upload the file you already have.
- Read three dates and the chance of your own.
- See the five tasks that move the finish most, and every task's P80 in the full report.
How it works
Read the plan
Your tasks, durations, links and lags, constraints and progress come from the file. Summary tasks take their dates from the tasks under them.
Vary every task
Each task with work left gets a duration drawn between 10% under and 25% over its plan, leaning late. Done tasks and milestones stay put.
Schedule it 2,000 times
Each run is scheduled through the links by the same critical path engine Onplana uses, and its finish date is recorded.
Read the percentiles
P50, P80 and P90 are the dates half, 80% and 90% of the runs finished by. The drivers are the tasks whose duration tracks the finish most closely.
Check it against your own file
Onplana's Schedule Risk Analyzer, released in October 2026, schedules an uploaded Microsoft Project or Primavera P6 file 2,000 times through its critical path engine, drawing each task's duration from a triangular range of 10% under to 25% over its planned value, and the same file always returns the same P50, P80 and P90 dates, so anyone can repeat a result.
What it costs, and what it does not do
The dates and the five drivers are free with no signup. The full report asks for an email address.
The honest limit: durations are varied independently and by one default range, so the spread comes out narrower than real projects, where late tasks tend to be late together. The free tool also schedules a Monday to Friday week without your holidays and does not level resources. Treat its P80 as a floor.
In Onplana, the same simulation runs on your live project with your own optimistic and pessimistic durations per task and the risks on your register, on the Business plan and above.
Frequently asked questions
My schedule has no three-point estimates. Is the result meaningless?
No, but read it as a default rather than your team's judgment. Every task with work left gets the same range: 10% under to 25% over its planned duration, drawn from a triangular distribution, which skews late the way real work does. The P80 then shows how much a typical overrun on every task adds up along your links. To use your own optimistic and pessimistic durations per task, save the schedule to an Onplana workspace.
Is 2,000 runs enough?
For the P50, P80 and P90 of a project finish, yes: past a few hundred runs, more runs change those dates very little. The tool aims for 2,000 and runs fewer only when a very large schedule would take more than about eight seconds, never fewer than 200. The report says how many it ran. The same file gives the same dates every time, so you can check a result by running it again.
Does it read my calendar, holidays and resource levels?
Not in the free tool. It schedules Monday to Friday at the hours per day your file states, reads each task's dates as whole days, and does not level resources. Durations are drawn independently, which makes the spread narrower than real projects, where one late task often makes its neighbours late too. Treat the P80 as a floor, not a ceiling.
What does P80 actually mean?
It is the date 80% of the simulated runs finished on or before. One run in five finished later. Many sponsors set a commitment at P80 and an internal target at P50, which is the median: half the runs finished by it.
Why is the chance of my own finish date so low?
Because the date in a plan is what happens if every task takes exactly its planned duration, and with a range that leans late, very few runs do that. A chance under 50% on the plan date is normal. The drivers list shows which tasks pull the finish later most often, which is where a buffer or a second look pays off.
Which files work?
Microsoft Project .mpp, Project XML (MSPDI) and Primavera P6 .xer, up to 22 MB and 2,000 tasks with work. Summary tasks are not simulated: their dates come from the tasks under them, as in the plan. Done tasks and milestones are held where the file puts them.
What happens to my file?
It is read on Onplana's servers to build the schedule, and the parsed plan is kept with your result so the report and the Save to Onplana step work. The raw bytes are not kept. No AI model sees the file. Your email, if you unlock the full report, is stored encrypted.
Keep the plan and the dates together.
Import the same file into a free Onplana workspace: the Gantt, the critical path and baselines on every plan.