Iterative Model: Definition, Advantages, Disadvantages & Examples

By Abhay Talreja

10/29/2025

My latest article - Empirical Process Control - The Key to Agile Success

The iterative model is a software development approach in SDLC where the project is broken into small, manageable iterations (cycles), with each iteration producing a working version of the software that is incrementally improved based on feedback until the final product meets all requirements.

Unlike the linear Waterfall model, the iterative model allows for continuous refinement and adaptation throughout development.

Key characteristics: Each iteration in the iterative model includes planning, design, development, and testing phases, producing a functional prototype or increment. Stakeholders provide feedback after each iteration, which informs the next cycle. This approach is ideal for projects with evolving requirements or when early user feedback is valuable.

Quick Answer: Iterative Model at a Glance

This comprehensive guide covers the iterative model in Software Development Life Cycle (SDLC), including what it is, its advantages and disadvantages, phases, when to use it, and how it compares to other SDLC models with real-world examples.

Table of Contents

• Introduction to the Iterative Model
• How the Iterative Model Works (4 Phases Per Iteration)
• Advantages of the Iterative Model
• Disadvantages of the Iterative Model
• Iterative Model and the Triple Constraint
• Comparing the Iterative Model to Other SDLC Models
• Conclusion
• Video
• Presentation used in the video
• Frequently asked questions

Introduction to the Iterative Model

The iterative model is a software development approach that involves breaking a project into small, manageable iterations.

Each iteration is a self-contained mini-project that results in a working version of the software.

The development team then uses feedback from stakeholders to refine and improve the product in subsequent iterations.

This process continues until the final product meets the desired requirements.

How the Iterative Model Works (4 Phases Per Iteration)

Unlike the linear Waterfall model that follows a strict sequential flow, the iterative model repeats a cycle of four key phases multiple times, with each iteration building upon the previous one.

Each iteration typically includes:

1. Planning and Requirements

Define the scope and objectives for the current iteration. The team identifies which features or requirements to implement in this cycle, prioritizing based on business value, risk, and dependencies.

Key Activities:

• Select features for the current iteration from the product backlog
• Define iteration goals and success criteria
• Estimate effort and allocate resources
• Identify risks and dependencies

Duration: Typically 1-3 days for a 2-4 week iteration

2. Design and Architecture

Create the design specifications for the selected features. This phase may involve updating system architecture, database schemas, user interfaces, and integration points.

Key Activities:

• Design system architecture and component interactions
• Create UI/UX designs and mockups
• Define data models and database schemas
• Document technical specifications

Duration: Typically 2-5 days depending on iteration complexity

3. Development and Implementation

Build the software features according to the design. Developers write code, create databases, and implement the functionality planned for this iteration.

Key Activities:

• Write application code following coding standards
• Implement database changes and data migrations
• Develop user interfaces and integrations
• Conduct code reviews and pair programming
• Perform unit testing on individual components

Duration: Typically 50-70% of iteration time (e.g., 7-14 days for a 2-week iteration)

4. Testing and Evaluation

Validate that the iteration meets requirements and quality standards. The team tests the new functionality, gathers stakeholder feedback, and identifies improvements for the next iteration.

Key Activities:

• Execute integration testing and system testing
• Conduct user acceptance testing (UAT) with stakeholders
• Gather feedback on functionality and usability
• Identify bugs and create defect reports
• Demonstrate working software to stakeholders
• Retrospective: Review what worked well and what needs improvement

Duration: Typically 20-30% of iteration time (e.g., 3-6 days for a 2-week iteration)

After completing one iteration, the team reviews feedback, updates requirements if needed, and begins the next iteration cycle. This process repeats until the software meets all requirements and stakeholders are satisfied with the product.

Iterative Cycle Visualization

Iteration 1: Plan → Design → Develop → Test → Working Increment v1.0
                                                         ↓
Iteration 2: Plan → Design → Develop → Test → Working Increment v1.1
                                                         ↓
Iteration 3: Plan → Design → Develop → Test → Working Increment v1.2
                                                         ↓
                                      ... Continue until complete ...
                                                         ↓
Final Product: Fully functional software meeting all requirements

Key Difference from Waterfall: In Waterfall, you complete ALL planning, then ALL design, then ALL development, then ALL testing.

In the iterative model, you complete planning → design → development → testing for a SMALL piece of functionality, then repeat the cycle for the next piece.

Advantages of the Iterative Model

The iterative model offers significant benefits that make it a popular choice for software development projects, particularly those with evolving requirements or high complexity.

1. Flexible and Adaptable to Change

The iterative model easily accommodates changes in requirements as the project progresses.

Each iteration provides an opportunity to adjust priorities, add features, or modify functionality based on new insights or changing business needs.

This flexibility makes it ideal for projects with evolving or uncertain requirements where the full scope isn't known upfront.

2. Early Feedback and Validation

Stakeholders can provide valuable feedback early and frequently in the development process, ensuring the final product aligns with their needs.

Each iteration produces a working version that users can interact with, providing tangible feedback rather than abstract requirements discussions.

This reduces the risk of building the wrong product.

3. Reduced Project Risk

By addressing high-risk or complex features early in the development process, the iterative model helps reduce project risk.

Technical uncertainties are explored in early iterations, allowing teams to identify and mitigate risks before they become critical issues.

This "fail fast" approach prevents costly late-stage discoveries.

4. Easier Project Management

With smaller, more manageable iterations (typically 2-6 weeks), project management becomes more straightforward and less overwhelming.

Progress is visible and measurable after each iteration, making it easier to track velocity, estimate completion, and communicate status to stakeholders.

5. Improved Software Quality

Frequent testing and feedback allow developers to identify and fix issues more quickly, leading to higher-quality final products.

Each iteration includes testing, ensuring defects are caught early when they're cheaper and easier to fix. Continuous integration and refinement improve overall product quality.

6. Incremental Delivery of Value

The iterative model allows for incremental delivery of working features, providing value to users sooner than waiting for a complete system.

Organizations can begin realizing ROI earlier and adjust priorities based on which features deliver the most value.

7. Better Risk Management Throughout

Continuous risk assessment occurs at each iteration, allowing teams to identify new risks early and adjust strategies accordingly. This ongoing risk management is more effective than one-time upfront risk analysis.

Disadvantages of the Iterative Model

While powerful, the iterative model comes with challenges that teams must address to succeed with this approach.

1. Requires Disciplined Planning and Management

The iterative model demands careful planning and organization to manage iterations and ensure the project stays on track.

Teams must define clear iteration goals, maintain backlogs, and coordinate work across multiple cycles. Without discipline, iterations can become chaotic and unproductive.

2. Less Predictable Timeline and Budget

It can be challenging to predict the exact number of iterations required to complete the project, making it difficult to estimate the project's completion date and total cost.

While individual iterations are time-boxed, the overall project duration may be uncertain, particularly if requirements continue evolving.

3. Requires Frequent Communication and Collaboration

The iterative model relies on constant communication between team members and stakeholders, which can be time-consuming and challenging to manage, especially for distributed teams.

Regular reviews, feedback sessions, and planning meetings require significant coordination and commitment from all parties.

4. Potential for Scope Creep

The flexibility of the iterative model may lead to scope creep if stakeholders continuously request changes or additions throughout the development process.

Without strong scope management and change control processes, projects can expand beyond original boundaries, affecting timelines and budgets.

5. May Not Suit Small or Simple Projects

For small projects with well-defined requirements, the overhead of managing multiple iterations may not be justified.

The waterfall model or a single development cycle might be more efficient for straightforward projects where requirements are stable and well-understood.

6. Requires Experienced Team Members

Successfully implementing the iterative model requires team members experienced in iterative development practices, including estimation, incremental design, and continuous integration.

Teams new to iterative approaches may struggle initially.

7. Documentation Can Lag Behind Development

With the focus on working software and rapid iteration, comprehensive documentation may be deprioritized or become outdated as the software evolves.

Teams must consciously maintain documentation or risk knowledge gaps.

Table 1: Advantages and Disadvantages of The Iterative Model in the Software Development Life Cycle (SDLC)

Iterative Model and the Triple Constraint

The triple constraint refers to the three primary factors that determine the success of a project: scope, time, and cost. In the iterative model, these factors are interrelated and must be carefully balanced to ensure project success.

The flexible nature of the iterative model allows for adjustments to the scope as the project progresses, but this may affect the overall time and cost of the project.

Comparing the Iterative Model to Other SDLC Models

The iterative model has its unique advantages and disadvantages, which set it apart from other SDLC models, such as the waterfall and agile models.

Iterative vs. Waterfall Model

The waterfall model is a linear approach to software development, where each phase is completed before moving on to the next. The iterative model, on the other hand, involves repeated cycles of development and refinement. Here are some key differences between the two:

• Flexibility: The iterative model is more flexible than the waterfall model, as it allows for changes in requirements and feedback during development.
• Feedback: The iterative model enables early feedback from stakeholders, while the waterfall model only allows for feedback after the entire project is completed.
• Risk management: The iterative model is better at managing risk, as high-risk features are addressed early in the development process, while the waterfall model does not allow for risk mitigation once the project has started.

Table 2: Comparison between The Waterfall Model and The Iterative Model in the Software Development Life Cycle (SDLC)

Conclusion

The iterative model is a valuable approach to software development that offers flexibility, early feedback, and risk reduction.

However, it also comes with its own set of challenges, such as the need for disciplined planning and frequent communication.

By understanding the advantages and disadvantages of the iterative model and how it compares to other SDLC models, you can choose the approach that best suits your project needs and goals.

Based on my experience, most of the projects have moved away from the waterfall model and are moving to one or other form of an iterative model for software development.

Video

This video is part of our scrum course. Please sign-up for the course to see the video.

Presentation used in the video

Frequently Asked Questions (FAQs) / People Also Ask (PAA)