PERT chart maker: free, online, from your schedule
Type your tasks, how long they take and what each one waits for, and the PERT chart draws as you type: early and late dates, float and the critical path in red. Or open a Microsoft Project or Primavera file.
Save as Project XML keeps the plan you typed: import it into a free Onplana workspace, or open it in Onplana Schedule, the free Windows and Mac app, to keep editing it.
What is a PERT chart?
A PERT chart is a network diagram of a project. Each task is a box, and an arrow from one box to the next says the second task waits for the first. PERT stands for Program Evaluation and Review Technique, a method developed for the US Navy in the late 1950s to plan large programmes with many dependent tasks. Microsoft Project calls the same picture the Network Diagram, and you may also see it called a precedence diagram or an activity-on-node diagram.
How do you read a box in a PERT chart?
- Early start and early finish: the soonest the task can begin and end, once everything it waits for is done.
- Late start and late finish: the latest it can begin and end without moving the project finish.
- Float: the difference, how many working days the task can slip on its own. A task with no float is on the critical path.
- Duration: working days, not calendar days, so weekends are skipped.
PERT chart or Gantt chart?
A Gantt chart puts each task on a calendar as a bar, which answers when. A PERT chart puts the tasks in the order their dependencies force, which answers what waits for what and which chain sets the finish date. Use the PERT chart to check the logic of a plan, and the Gantt chart to run it week to week. The Gantt chart generator draws the other view.
What is the critical path on a PERT chart?
The critical path is the longest chain of dependent tasks from start to finish. Its tasks have no float, so a day lost on any of them is a day lost on the project. This chart draws them with a red border. Shortening the project means shortening that chain, or overlapping its tasks with start-to-start links and leads.
What about three-point estimates?
Classic PERT also estimates each task three ways, optimistic, most likely and pessimistic, to put odds on the finish date. This chart uses one duration per task. To see how likely your finish date is from three-point estimates, use the free schedule risk analysis.
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Frequently asked questions
What is a PERT chart?
A PERT chart is a network diagram of a project: each task is a box, and an arrow from one box to another says the second task depends on the first. PERT stands for Program Evaluation and Review Technique, a method developed for the US Navy in the late 1950s. The chart shows the order work has to happen in and which chain of tasks sets the finish date.
Is this PERT chart maker free?
Yes. Type your tasks or open a file, read the chart and export it as a PNG picture or a PDF, with no account and nothing to install.
Is what I type uploaded?
No. The table is scheduled and drawn in your browser, and the picture, the PDF and the Project XML are made there too. Nothing you type is sent to Onplana.
What do the numbers in a box mean?
The top row is the early start, the duration and the early finish: the soonest the task can begin and end. The bottom row is the late start, the total float and the late finish: the latest it can begin and end without moving the project finish. Float is the gap between the two.
How do I write a predecessor with a lag?
Write the row number, then the link type if it is not finish to start, then the lag in working days. 3SS+2d means "start two working days after row 3 starts"; 4FF means "finish when row 4 finishes"; 2-1d starts one day before row 2 finishes. Separate several predecessors with commas.
Which tasks are on the critical path?
The ones with no float: any delay to them moves the project finish. The chart draws them with a red border, and the arrows between them form the critical path.
What is the difference between a PERT chart and a Gantt chart?
A Gantt chart draws each task as a bar on a calendar, so it answers when. A PERT chart draws the tasks as boxes joined by their dependencies, so it answers in what order and what drives the finish. Most schedulers read both, and the file viewer on this page shows both views of the same plan.
Can I open a Microsoft Project or Primavera file as a PERT chart?
Yes. Choose Open a file, open your .mpp, Project XML or .xer, then switch the view to Network diagram. A Project XML file opens in your browser; other formats are converted on Onplana's servers after you say so.
Can I keep editing the plan?
Yes. Save it as Project XML and open it in Onplana Schedule, the free Windows and Mac app, or import it into a free Onplana workspace, where your team plans together on the Gantt chart.