What is Spiral model?

What is Spiral model in SDLC?

  1. The spiral model is the combination of the waterfall model and prototype model.
  2. Each phase of the spiral model is to start with a goal and end with reviewing the customer.
  3. In the spiral model, software is developed in a series of incremental releases.
  4. The spiral model develops with many loops and each loop of the spiral model is called a phase of the spiral model.
  5. All the phases are verified by the project manager depending on the project analysis and risk also.

Here below we show the spiral model diagram and the radius of the point in the model represents the cost of the project. This is a circular loop and every phase of this model divided into the quadrants.

Diagram of spiral mode:-

The functions of his diagram of the spiral model are given below in brief:-

spiral model
spiral model

Phases of the spiral model:-

  1. Identification
  2. Design 
  3. Evolution and risk analysis
  4. Building and construct

1. Identification:-

In this phase of the spiral model all the requirements of the system identifying and collect the necessary data.

All these details are gathered by the customers And after understanding all the phases of the projects a documented criteria are covered. After discovering the market requirements projects are started for design.

2. Design:-

After gathering all the important data, the design process of the project is started based on the spiral model technique.

All the requirements as like architecture and functional and logical modules are covered in this phase.

3. Construct and build:-

After designing the project the production of the actual project is started. A poor concept is using early to take the feedback of the customers.

 Then after apply all the efforts which is understood at the time of identification is used.All the important functions, modules and versions are builds in this phase of the spiral model.

4. Evaluation and risk analysis:-

This is a very important stage of the spiral model because in this stage identifying the technical risk and eliminate them.

But these are going on after the customer feedback.

When to use Spiral model?

The spiral model used for the software development process, where the requirements are very unclear and risk is very high.

  • The projects are very large for the spiral model using.
  • When the high budget project is developing.
  • The spiral model used where risk is very high.
  • The spiral model is used when deliverance is required to frequent.
  • When the software requirements are unclear then the spiral model is used.
  • Where the requirements are very complex.
  • When the changes require possible at any time for customer satisfaction.
  • The spiral model used where time is infinite and unclear for completion of the project.

Spiral model applications:-

Spiral model used in the software development industry where the software development process is always going on. Software developers used this model according to his requirements and when the projects full fill the project requirements.

Pros and Cons of Spiral model

Advantages of spiral model:-

  1. The spiral model is very good for large projects.
  2. The spiral model is used where risk is very high.
  3. Project monitoring is very easy in the spiral model.
  4. By using the spiral model you can easily eliminate risks.
  5. Changes are accumulated at the last stage.
  6. Development is very unique and fast as compare to other models.
  7. In spiral model more features are easily added for users.
  8. All the phases are changes after the customer’s feedback; if the customer is not satisfied then it changes its features.
  9. Customer satisfaction is easily covered in this spiral model.
  10. Users can easily see the system early.

   Disadvantages of spiral model:-

  1. The spiral model is not suitable for low-risk projects.
  2. Spiral model cost is very high.
  3. In spiral model rules are very strict.
  4. The spiral model phase is very important expert developers are required in this model.
  5. Low projects are not suitable.
  6. Documentation is very high.
  7. It maybe goes for infinitely sometimes.
  8. The spiral model is very complex than the other models.
  9. Time estimation is a very difficult task due to no. of unknown phases in the spiral model initially.
  10. In the spiral model, there is large no. of  Stages are needed for the documentation.

Limitations of the spiral model

There are a lot of limitations for spiral model

  1. Very high cost

               The spiral model is very expensive for the software development series process; if our projects are very small then it is not suitable for them.


The spiral model is very complex as compared to the other model as like the waterfall model or prototype model of software engineering. Its rules are very strict and developers must follow them. Documentation limit is very high in the spiral model.

3. Management system is very hard

You already knows this is used for large projects so management is very hard for them. There are a lot of phases according to the project then each phase must be emolument so that’s why it is very hard to manage.

4.Risk analysis dependency

Risk handling is another point of the spiral model that very complex.


The spiral model is a software development model that is used for high budget and large projects, where risk is very high.

Advanced topics for software engineering models:-

Characteristics of computer

what is waterfall model in sdlc

Prototype model in software engineering

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