Spiral Model

Spiral Model – Definition, Phases, Advantages & Disadvantages

What is a Spiral Model?

Definition : The spiral model in software engineering is one type of model of the software development lifecycle. SDLC is a step-by-step procedure to develop software or applications. It is also similar to the incremental model. In this spiral model sdlc, there are four main stages: Planning, Risk Analysis, Engineering,
and Evaluation.

Spiral Model Phases

There are four spiral model phases: 

In this phase, first of all, requirements gathered from customers during this planning stage. Requirements such as CRS (Customer Requirement Specification), SRS(Software Requirement Specification), and BRS(Business Requirement Specification).

Risk Analysis:
Due to main focus on this phase is identifying the risk and its solutions. So if any kind of risk found during this phase, then solutions implemented.


During this phase, the software developed with testing. So both development and testing is completed during this phase.

The main purpose of this phase is to allow the client to evaluate the output before starting the next spiral.

Spiral Model Diagram

Spiral Model
Diagram of Spiral Model

Spiral Model Advantages And Disadvantages

Advantages and Disadvantages of Spiral Model are shown below

Advantages Of Spiral Model

  1. It is good for big and complex projects
  2. It can be added at the mid-level of projects.
  3. It has strong controls on documentation.
  4. In this phase, it has more chances to produce software in the early software life cycle.

Disadvantages Of Spiral Model

  1. This model can be costly to use.
  2. It should require high expertise in risk analysis.
  3. The dependency on risk analysis is high due to the project’s success.
  4. It is not suitable for small projects.


  1. This model is useful when costs and risk evaluation required.
  2. When there is a medium to the high-risk project at that time we can use this model.
  3. When customers are not clear about their requirements.
  4. When rapidly changes expected 
  5. Requirements are complex.


So as above, spiral model of software development is mainly focused on risk-based projects. Also, this model is used when the requirements are complex. If you are looking for more sdlc models then please visit below link.

1. SDLC – V Model

2. SDLC – Waterfall Model

3. SDLC – Agile Model

4. RAD Model

5. Prototype Model

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