Gantt Chart vs PERT Chart vs Timeline: Which to Use

By Dr. Ahmed Mortuza Saleque · Updated November 11, 2026 · How we check our content

The short answer

A Gantt chart is a bar chart of tasks against a calendar, so it shows when each task happens and how long it takes. A PERT chart is a network of boxes and arrows that shows which tasks depend on which, and helps find the critical path. A timeline only shows key dates. Use PERT to plan the logic, then a Gantt chart to schedule and communicate it.

Open the Gantt Chart Maker →

Side by side

	Gantt chart	PERT chart	Timeline
Shape	Bars on a calendar	Boxes joined by arrows	Points on a line
Best at	When and how long	Order and dependencies	Key dates at a glance
Shows durations	Yes, bar length	As numbers in boxes	Rarely
Shows dependencies	Optional arrows	Yes, the whole point	No
Critical path	Can be highlighted	Found directly	No
Easy for funders and clients	Yes	Less so	Yes

Worked example: five tasks

A small study, with durations in weeks and what each task must wait for.

Task	Weeks	Depends on
A. Design survey	2	–
B. Ethics approval	4	A
C. Recruit participants	3	A
D. Collect data	5	B and C
E. Analyse and report	3	D

Finding the critical path

Path A → B → D → E takes 2 + 4 + 5 + 3 = 14 weeks.
Path A → C → D → E takes 2 + 3 + 5 + 3 = 13 weeks.
The longest path, A → B → D → E, is the critical path: the project cannot finish in under 14 weeks.
Task C has 1 week of slack. It can start a week late without delaying the end.

A PERT chart makes this logic visible. A Gantt chart then places the same tasks on a calendar: in the Gantt Chart Maker you can link each task to the one it waits for and show the arrows.

Three-point estimates in PERT

PERT originally estimated each task with three numbers: optimistic (O), most likely (M) and pessimistic (P). The expected time is (O + 4M + P) ÷ 6. Ethics approval with O = 3, M = 4 and P = 8 weeks gives (3 + 16 + 8) ÷ 6 = 4.5 weeks. The method puts weight on the most likely value while still accounting for a long tail.

And Kanban or a roadmap?

Kanban board: columns of cards (to do, doing, done). Good for ongoing work without fixed dates; no time axis.
Roadmap: a high-level Gantt chart of themes or releases by quarter, with little task detail. The Roadmap style in the Gantt Chart Maker gives this look.

Common questions

Is a PERT chart better than a Gantt chart?

Neither is better; they answer different questions. PERT shows dependencies and the critical path, Gantt shows the schedule. Many projects use both.

What does PERT stand for?

Program Evaluation and Review Technique, developed for the U.S. Navy Polaris missile programme in the late 1950s.

Can a Gantt chart show dependencies?

Yes. Arrows from the end of one bar to the start of another show that a task waits for another.

What is the difference between a Gantt chart and a timeline?

A timeline marks dates and events on a single line. A Gantt chart gives each task its own row and a bar showing how long it lasts.