Gantt Chart Explained: Examples and How to Create One

A Gantt chart is a project schedule that displays tasks as horizontal bars along a timeline. Each bar shows when an activity starts, when it finishes, and how long it lasts. It helps you see which tasks overlap, which must happen in sequence, and where delays could affect later work.

If you searched for “gant chart,” the correct spelling is Gantt chart.

For a website launch, a Gantt chart can show when content writing, design, development, and testing should happen. Instead of keeping separate deadlines in messages and notebooks, you get one shared view of the schedule.

The chart does not guarantee an on-time launch. Its value comes from making the plan visible—and keeping that plan realistic as work changes.

What Does a Gantt Chart Show?

A basic Gantt chart combines a task list on the left with a timeline on the right. More detailed versions include owners, dependencies, milestones, and progress.

Microsoft’s documentation describes the Gantt view as a task grid paired with timeline bars, with links showing task dependencies. Milestones commonly represent significant events using zero duration.

Duration is different from effort. A task requiring six hours of effort might span three working days if its owner can contribute only two hours each day.

That distinction matters when a project shares people with other responsibilities.

How to Read a Gantt Chart

Start with the date scale. A chart organized by weeks is useful for an overall project review; daily detail helps with short projects and handoffs.

Then read across each task row:

1. Find the bar’s left edge: This marks the scheduled start.
2. Find its right edge: This marks the scheduled finish.
3. Look vertically for overlapping bars: These activities are planned to happen simultaneously.
4. Follow dependency lines: These show relationships between tasks.
5. Check milestones and progress: Identify upcoming decisions and unfinished work.

Read the legend before interpreting colors. Blue might mean planned work in one chart and completed work in another. A red bar does not universally mean overdue.

Also distinguish scheduled dates from actual dates. A bar ending yesterday does not prove that the task is complete. You need a status update or recorded actual finish.

Gantt Chart Example: Planning a Small Website Launch

Imagine a small business preparing a five-page website. The following illustrative schedule assumes:

• Work happens Monday through Friday.
• No public holidays or staff absences affect these dates.
• Copywriting and design have separate owners.
• Development begins after both copy and design are approved.
• Testing includes minor fixes and launch approval.

Dates below use day–month–year to avoid confusion between regional date formats.

Here is the same plan as a simple visual:

The table specifies dependencies; the visual makes the timing and overlap easier to see.

What Happens If a Task Slips?

Suppose copy approval moves from Friday, 6 November, to Monday, 9 November. Under this plan’s next-working-day handoff rule, development starts Tuesday, 10 November.

If all later durations stay unchanged, testing finishes Monday, 16 November, and the launch-ready milestone moves to Tuesday, 17 November.

Design, however, could finish one working day later without changing development’s original start. That spare time is called float.

The sequence that determines the earliest project finish is the critical path. Here, it runs through scope, copy, development, and testing. Resource shortages or changed dependencies can alter it.

How to Create a Gantt Chart Step by Step

1. Define the Outcome

Write down what the project must deliver and what counts as finished.

For this example:

A five-page website with approved content, working navigation, tested contact forms, and launch approval.

“Create a website” leaves too much open. Clear completion criteria help prevent forgotten work and disagreements during review.

2. Break the Project Into Manageable Tasks

List the activities needed to produce that outcome. Use action-focused names such as “Approve homepage copy” or “Test contact form.”

A task should be small enough to estimate and assign, but substantial enough to track meaningfully. Avoid adding every email and short conversation as a separate bar.

Include reviews, approvals, and handoffs. These consume calendar time even when they require little hands-on effort.

3. Estimate Durations With the People Doing the Work

Ask task owners how much effort they expect and when they are available.

Check:

• Existing commitments.
• Review turnaround times.
• Access to files, accounts, and materials.
• Likely revisions.
• Leave and nonworking days.

Record uncertainty instead of hiding it. If development depends on unfamiliar integrations, explain the assumption and allow time to investigate before committing to a launch date.

4. Assign One Accountable Owner

Several people may contribute to a task, but one person should provide its status and coordinate completion.

Check overlapping assignments. Two bars can run in parallel on a chart while still competing for the same person’s time.

If your designer also builds the website, schedule both responsibilities around their actual availability.

5. Link Dependencies

A common relationship is finish-to-start: the next task begins after its predecessor finishes.

For the website example, development depends on two predecessors—approved copy and approved layouts. Recording only the design dependency would hide a potential content delay.

Other relationships can connect task starts or finishes, but beginners should use the simplest relationship that accurately describes the work. Scheduling software can use these links to recalculate affected dates, depending on its settings and constraints. Microsoft Support

6. Add Milestones and Check the Finish Date

Use milestones for meaningful events such as scope approval, client acceptance, or launch readiness.

A milestone is not a substitute for the work required to reach it. If deployment takes half a day, add a deployment task before the “Website live” milestone.

Now check whether the proposed deadline follows from the durations, dependencies, and available people. If it does not, discuss scope, capacity, or the deadline itself.

7. Save the Plan and Update It

Save an approved starting version, often called a baseline, before work begins.

Then maintain the current forecast separately. Record actual starts, actual finishes, remaining work, and blockers.

A weekly update may suit a longer project. A short launch schedule may need daily reviews near release. Update immediately when a change affects another person’s work.

How to Make a Simple Gantt Chart in a Spreadsheet

A spreadsheet is often sufficient when one person maintains a small schedule.

Set Up Your Planning Columns

Create these columns:

A: Task
B: Owner
C: Start
D: Finish
E: Working days
F: Predecessor
G: Progress

Starting in H1, enter consecutive calendar dates across the sheet. Store them as real spreadsheet dates and display them as dd mmm.

For a Monday–Friday calendar, calculate duration in E2 with:

=NETWORKDAYS(C2,D2)

If holiday dates are listed in Z2:Z20, use:

=NETWORKDAYS(C2,D2,$Z$2:$Z$20)

NETWORKDAYS counts working days between the start and finish, including eligible boundary dates, while excluding weekends and listed holidays. Use NETWORKDAYS.INTL when your weekend pattern differs.

Create the Timeline Bars

Select your timeline area, such as H2:V20, and add a conditional-formatting rule using:

=AND(H$1>=$C2,H$1<=$D2,$A2<>"")

Choose a fill color. Each task row now shows a bar covering its scheduled date range.

This rule colors calendar dates, including weekends inside a longer task. Shade nonworking-day columns separately so readers understand that a continuous bar does not mean weekend work.

Calculate a Finish Date From Duration

If C2 contains a valid working-day start and E2 contains a positive whole-number duration, use:

=WORKDAY(C2,E2-1,$Z$2:$Z$20)

Subtracting one counts the start date as the first working day. WORKDAY excludes weekends and supplied holidays; WORKDAY.INTL supports alternative weekend patterns.

Choose whether you enter the duration or the finish date manually. Do not put mutually dependent formulas in both columns.

For zero-duration milestones, use a separate marker or row. The formula above is for ordinary tasks.

Writing a predecessor ID in column F does not automatically reschedule tasks. That requires additional formulas or scheduling software.

Copyable Gantt Chart Planning Template

Copy this table into your spreadsheet and replace the placeholders:

Above the table, record the project’s working week, holidays, date format, reporting time zone, and last update date.

For international teams, give timed handoffs an explicit zone—for example, 15:00 UTC. “Friday afternoon” can mean different deadlines to different colleagues.

When Is Dedicated Software Useful?

Check the specific plan’s capabilities before subscribing. A timeline view does not necessarily include dependency scheduling or resource management.

For related options, read a guide to project management software.

Common Gantt Chart Mistakes

Forcing tasks into an unrealistic deadline. Shortening bars does not reduce the work. Revisit the scope, staffing, sequence, or delivery date.

Missing approval dependencies. A completed draft may still need a decision before the next activity can begin.

Treating elapsed time as progress. Half the scheduled days passing does not mean half the work is complete. Use deliverables or an estimate of remaining work.

Ignoring different calendars. Regional holidays, part-time schedules, and supplier working hours can change handoffs.

Leaving old dates untouched. A chart showing last week’s expectations cannot reliably guide today’s decisions.

Expecting the chart to manage everything. Keep risks, budgets, decisions, and detailed requirements in suitable supporting records.

FAQs

What is a Gantt chart used for?

It is used to plan and track work across time, particularly when a project has multiple tasks, deadlines, and dependencies.

Is a Gantt chart the same as a timeline?

A timeline can show only major dates. A Gantt chart usually provides task-level bars showing start dates, finish dates, and durations.

Can I create a Gantt chart for free?

Yes. A spreadsheet with date columns and conditional formatting can provide a basic version. More advanced scheduling features may require additional setup or paid software.

How many tasks should it contain?

Include enough detail to manage ownership, handoffs, and deadlines. Group related work when the chart becomes difficult to read, while keeping meaningful dependencies visible.

Can a Gantt chart prevent delays?

No. It can reveal scheduling problems and show the likely effects of changes. Preventing or resolving delays still requires decisions, communication, and available resources.

Final Words

Start with a clear outcome, realistic tasks, accountable owners, and honest estimates. Connect dependent activities, check the working calendar, and update the schedule as facts change.

A useful Gantt chart helps everyone answer three questions: What happens next, who owns it, and what could change the finish date?