List dated events
Supply the milestone labels and dates from the project plan. Record dependencies explicitly instead of inferring them from spacing.
Gantt Chart Maker: Dependencies and Critical Path
Give it tasks, durations and what depends on what. It calculates the working-day dates, validates the dependencies and draws the critical path — rather than asking you to position bars by eye.
A Gantt chart is a horizontal bar chart of a schedule: each task is a bar running from its start date to its finish date, stacked in rows down the page, with the dependencies between them drawn as links. It answers two questions a task list cannot — what has to finish before this can start, and what happens to the end date if this task slips. Named after Henry Gantt, who popularised the form around 1910, it remains the standard way to show a project plan to people who are not managing it day to day.
Prism · real output
Keep dates and dependencies visible.
Inspect an actual Prism schedule capture. Supply dated events and dependencies, then verify their order and relationships against the project plan.
Prism dependency schedule
An actual Prism workflow capture from a fictional example. It demonstrates a schedule view, not a promise about project duration.
Inspect the source brief or data
A captured Prism result showing a dependency schedule. Use your own dated events and verify the order and dependencies.
Read the sample review notes
The tasks and dates are fictional and do not describe a customer project.
Check order and relationships
Verify that chronology, labels and dependency links match the source plan. Correct the supplied events before sharing the visual.
Inspect the export
Review the full schedule at its intended size and include context for dates or dependencies that need explanation.
Dates, dependencies and schedule assumptions
Check the project calendar, task dates, duration, dependency links and float against the supplied plan. Confirm that milestones and the critical path still make sense after edits; the rendered timeline does not verify a project's schedule.
Labels, evidence and readable exports
Keep task names and date labels legible at the intended size. Inspect dependency direction, source notes, alternative text and the full export before sharing the schedule.
A rendered schedule preserves the inputs it receives; it does not validate project dates, dependencies or delivery commitments.
Where most Gantt charts go wrong
Not in the drawing — in the arithmetic behind it. A chart made by dragging bars around encodes whatever the person dragging believed at the time, and nothing recalculates when that turns out to be wrong.
Calendar days, not working days
A ten-day task starting Thursday does not finish a week on Saturday. Prism counts working days and skips the holidays you declare, so the finish date is the one your team will actually hit.
Dependencies that are decorative
Arrows drawn between bars usually mean nothing to the drawing tool. Here a predecessor is a constraint: it is validated, and a circular or impossible dependency is reported rather than rendered.
No critical path
Without float, every task looks equally urgent. Prism computes CPM float and marks the critical path, so you can see which slips move the end date and which absorb quietly.
What is a Gantt chart? A worked example, element by element
| Element | What it shows | Why it matters |
|---|---|---|
| Bar length | Task duration in working days | The estimate you are actually committing to, once weekends and holidays are removed |
| Dependency link | This task cannot start until that one finishes | Turns a wish-list of dates into a schedule that recalculates when something moves |
| Float (slack) | How long a task can slip without moving the end date | Tells you where to spend attention; zero float means the deadline moves with it |
| Critical path | The chain of zero-float tasks | The only sequence where saving a day saves a day on the project |
| Milestone | A zero-duration checkpoint | Marks a decision, gate or hand-off that others are planning around |
| Progress | How much of a bar is complete | Separates "started" from "on track", which a bar alone cannot show |
How to make a Gantt chart with Prism
1
List the tasks and durations
Task name and how many working days it takes. Durations, not dates — the dates are derived.
2
Name the predecessors
Say which task must finish first. This is the part that makes it a schedule rather than a picture of one.
3
Set the start date and non-working days
Declare the project start and any holidays. Working-day arithmetic handles the rest.
4
Render and export
Prism draws the bars, links, milestones and critical path, and exports the schedule with computed float alongside the graphic.
Gantt chart template, Gantt chart in Excel, or a schedule engine?
A Gantt chart template is the right tool when the plan is small and stable — six tasks, one owner, no real dependency chain. You fill in bars, it looks like a plan, and nothing needs to recalculate because nothing is going to move.
A Gantt chart in Excel is the usual next step, built from a stacked bar chart with a transparent first series. It works, and it is genuinely useful when the numbers already live in a spreadsheet. What it does not give you is dependency validation or critical-path analysis: the bars are positioned by the dates in your cells, so if a date is wrong the chart is confidently wrong with it. Prism exports an editable XLSX schedule on a paid plan, so the spreadsheet stays available — it just is not where the arithmetic happens.
Prism is the third option: you describe the work and the constraints, and the schedule is computed. That matters once a plan has enough dependencies that you cannot hold the consequences of a slip in your head — which is usually sooner than people expect.
Frequently Asked Questions
What is a Gantt chart?
A Gantt chart is a horizontal bar chart of a schedule: each task is a bar running from its start date to its finish date, with dependencies drawn between them. It answers two questions a task list cannot — what must finish before this can start, and what happens to the end date if this slips. It is named after Henry Gantt, who popularised the form around 1910.
How do I make a Gantt chart?
List the tasks with durations in working days, name each task's predecessors, set the project start date and any non-working days, then render. Prism computes the dates from the durations and dependencies rather than asking you to place bars, so moving one task recalculates everything downstream of it.
Can I make a Gantt chart in Excel instead?
Yes — the usual method is a stacked bar chart with the first series made transparent, and it is a reasonable choice when the data already sits in a spreadsheet. The limitation is that Excel positions bars from the dates in your cells; it does not validate dependencies or compute a critical path, so a wrong date produces a confidently wrong chart. Prism exports an editable XLSX schedule on a paid plan if you want the spreadsheet as well.
Is a Gantt chart template enough?
For a small, stable plan, often yes. A template is fine when there are a handful of tasks, one owner and no real dependency chain, because nothing needs to recalculate. It stops being enough as soon as tasks depend on each other and dates start moving — at that point you need the schedule computed rather than drawn.
What is the critical path, and what is float?
Float, or slack, is how long a task can slip without moving the project end date. The critical path is the chain of tasks with zero float — the only sequence where saving a day actually saves a day overall. Prism computes both, so you can tell which delays matter and which absorb quietly. Without them every task on a chart looks equally urgent, which is how teams end up expediting work that had a fortnight of slack.
Does it handle weekends and holidays?
Yes. Durations are in working days, and you can declare non-working days so they are excluded from the arithmetic. This is the most common source of quietly wrong finish dates — a ten-day task starting on a Thursday does not finish a week on Saturday, but a calendar-day calculation will say it does.
Is it spelled Gantt or Gant chart?
Gantt, with two Ts — after Henry Gantt. "Gant chart" is a very common misspelling and means the same thing. Both refer to the same bar-chart-of-a-schedule; nothing about the format changes with the spelling.
Explore the Prism toolkit
Keep the project schedule behind the chart
Prism makes the visual. For saved tasks, milestones, dependencies and reviewed project dates, explore project scheduling in Keystone. A chart made from captured facts is not a live project schedule.
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