Quick Answer

The project life cycle is the series of phases a project moves through from start to finish. Each phase ends with one or more deliverables, and phase gates between phases let leaders confirm the project still deserves to continue. The type of life cycle you use follows from how you plan to deliver the work.

What is the project life cycle?

The project life cycle is the shape of a project over time. It breaks the work into phases, each a group of related activities that ends with one or more deliverables. Between phases sit phase gates, also called stage gates or kill points, where a sponsor or governance board reviews the results and decides to continue, change course, or stop.

Phase names depend on the industry and the work. A construction project might run feasibility, design, construction, and commissioning. The life cycle you choose follows from your development approach, the way you plan to produce the deliverables.

That gives you a range of life cycles. Predictive life cycles fix scope early and move through phases in sequence. Iterative and incremental life cycles refine the product through repeated cycles or deliver it in usable pieces. Adaptive life cycles work in short, timeboxed iterations, with scope that evolves from customer feedback. Hybrid life cycles combine them, such as a predictive hardware track running alongside an agile software track.

The most common PMP candidate confusion point is mixing up life cycle phases with the five focus areas in the PMBOK® Guide, Eighth Edition: Initiating, Planning, Executing, Monitoring and Controlling, and Closing. Focus areas are not phases. They describe the kind of project management work being done, and they repeat inside every phase. A design phase has its own initiating, planning, and closing work, and so does the build phase that follows it.

A four-phase project life cycle with phase gates, showing the five focus areas repeating inside each phase Four phases run left to right in order: feasibility, design, build, and handover. Orange diamonds between the phases mark three phase gates where the sponsor decides to continue, change course, or stop. Inside every phase, the same five focus areas appear as a small repeating loop: initiating, planning, executing, monitoring and controlling, and closing. Phases happen once, in sequence. Focus areas repeat within each phase. Phases run once, in order. Focus areas repeat inside each one. Feasibility Is it worth doing? Design What exactly will we build? Build Make it and test it Handover Transfer to operations I P E MC C Focus areas repeat I P E MC C Focus areas repeat I P E MC C Focus areas repeat I P E MC C Focus areas repeat Gate 1 Gate 2 Gate 3 Project start Project finish I Initiating, P Planning, E Executing, MC Monitoring and Controlling, C Closing. Orange diamonds are phase gates, where the sponsor decides to continue, change course, or stop.
PMTraining framework showing a four-phase predictive life cycle with phase gates and the five PMBOK 8 focus areas repeating inside each phase. Phase names are illustrative.

Watch the project life cycle explained

Our short video explainer walks through phases and phase gates.

How it works in practice

A county bridge replacement. The project runs feasibility, design, construction, and closeout, with a gate between each phase. At the design gate, the estimate comes in 18% over the approved budget. Because the gate exists, the board sees the gap before a single crew mobilizes. It approves a narrower deck and a revised budget, and construction starts on numbers everyone has signed.

A medical device with a companion app. Imagine a team building a connected glucose monitor. The hardware follows a predictive life cycle, because regulatory approval needs fixed design reviews. The app team works in two-week iterations. The tracks meet at shared milestones tied to the hardware gates, so the app is ready to test the week prototypes arrive.

We often see candidates draw the five focus areas as one left-to-right timeline. That picture breaks the moment a project has more than one phase.

Where to learn more

A Guide to the Project Management Body of Knowledge (PMBOK® Guide) is the primary home for this topic. The Eighth Edition, published in November 2025, covers predictive, adaptive, and hybrid life cycles and restores the five focus areas, which apply across the whole life cycle.

The Agile Practice Guide, co-published by PMI and the Agile Alliance, goes deeper on iterative, incremental, and adaptive life cycles.

Frequently Asked Questions

What is the difference between the project life cycle and the product life cycle?

The project life cycle ends when the project closes. The product life cycle runs from concept through development, growth, maturity, and retirement, and it usually spans several projects.

How many phases does a project life cycle have?

There is no fixed number. PMI does not prescribe phase names or a phase count. Organizations choose phases that fit their work and governance, from four phases on a small internal project to a dozen gated phases on a regulated capital program.

Conclusion and next steps

Choose the life cycle before you choose the tools. Name the phases, set the gates, and make sure your team knows that planning and closing happen in every phase, not only at the ends of the project.

Our live PMP certification classes work through life cycles, development approaches, and the PMBOK 8 focus areas with an experienced instructor.

About the Author

Christopher Scordo, PMP, ITIL, is Founder and Managing Director of PMTraining, a PMI Premier Authorized Training Partner that has trained more than 175,000 professionals. More about the team.

Related reading: What is Project Planning? and How to Effectively Blend Agile and Waterfall Project Management Styles.

Sources:

Project Management Institute, A Guide to the Project Management Body of Knowledge (PMBOK® Guide), Eighth Edition, and The Standard for Project Management

Project Management Institute and Agile Alliance, Agile Practice Guide

PMTraining, Project Life Cycle Explained: Phases and Phase Gates (video), 2026