Gantt Chart

A Gantt chart is a horizontal-bar schedule view that plots tasks against a timeline, showing start dates, end dates, dependencies, and milestones. Each task is a bar whose length equals its duration. Dependencies — “Task B can’t start until Task A finishes” — are shown as arrows connecting bars. Milestones (key deliverables, sign-offs, launch dates) appear as diamonds or flags.

The Gantt chart was popularised by Henry Gantt in the early 20th century for manufacturing scheduling. It remains the most universally understood project schedule format — the one format you can put in front of a CEO, a client, or a contractor and have them understand what’s happening without explanation.

Concrete example

A software product launch has five phases:

1. Discovery (weeks 1–2): stakeholder interviews, requirements doc
2. Design (weeks 3–5): wireframes, UI designs, prototype
3. Development (weeks 4–8): frontend + backend, design overlaps with start of development
4. QA (weeks 7–9): testing begins when core features complete, overlaps with development
5. Launch (week 10): go-live, dependent on QA sign-off

In a Gantt chart, you can see at a glance that Design and Development overlap (weeks 4–5), that QA and Development overlap (weeks 7–8), and that Launch is blocked by QA completion. If QA takes an extra week, the chart immediately shows Launch sliding by one week — without recalculating anything manually.

Why it matters

Gantt charts are a communication tool more than a planning tool. The value is that they translate project complexity into a format stakeholders can read in 10 seconds. “We’re in week 6, we’re on track, the critical path runs through QA in weeks 7–9, any delay there pushes launch” — all visible without a verbal explanation.

The failure mode: Gantt charts that are built once and never updated. A Gantt chart that reflects the plan from week one is not useful in week six. The discipline is maintaining the chart as the plan changes — which is where software tools earn their cost.

The PM software Gantt gap — what the marketing page doesn’t tell you

Not all Gantt implementations are equal:

• Full CPM Gantt (Microsoft Project, Primavera P6, Smartsheet): resource loading, critical path calculation, baseline tracking, earned value management. Used in construction and large-programme management.
• Task dependency Gantt (monday.com Standard, ClickUp Business, Asana Advanced, Wrike Team): drag-to-reschedule, dependency linking, milestone marking. Adequate for 90% of commercial teams.
• Read-only timeline view (Trello, Notion, Basecamp): shows when tasks are due, but doesn’t link dependencies or recalculate cascading changes. Marketing calls it a “Gantt” — it isn’t.

Key pricing gates for Gantt:

• monday.com: Standard (£10/seat) — full dependency Gantt
• ClickUp: Unlimited (£5/seat) — basic; Business (£10/seat) — full dependencies
• Asana: Advanced only (£24.99/seat) — Starter has no Gantt
• Wrike: All paid tiers including Team (£8.21/seat)
• Smartsheet: Pro (£6.20/seat) — the cheapest full dependency Gantt in the category

Tools that do Gantt properly at each price tier

• Under £10/seat: Smartsheet Pro (£6.20) — full dependency Gantt + critical path; Wrike Team (£8.21) — dependency Gantt
• £10/seat: monday.com Standard (£10) — dependency Gantt; ClickUp Business (£10) — dependency Gantt
• £24+/seat: Asana Advanced (£24.99) — full timeline; Microsoft Project Plan 1 (£8.10, but needs Plan 3 at £24.30 for resource management)

Related concepts

• Critical Path Method (CPM) — the scheduling calculation that identifies which tasks, if delayed, will push the project end date
• Dependency — the task-to-task ordering constraint that Gantt charts visualise as arrows
• Milestone — the key checkpoints that appear as diamonds or flags on a Gantt chart