The COCOMO Model Explained with Diagram

The COCOMO Model

The COCOMO model is an empirical model based on project experience.

  • Well-documented, ‘independent’ model which is not tied to a specific software vendor.
  • Long history from initial version published in 1981 (COCOMO-81) through various instantiations to COCOMO 2.
  • COCOMO 2 takes into account different approaches to software development, reuse, etc.


Project complexity Formula Description
Simple PM = 2.4 (KDSI)1.05 * M Well-understood applications developed by small teams.
Moderate PM = 3.0 (KDSI)1.12 * M More complex projects where team members may have limited experience of related systems.
Embedded PM = 3.6 (KDSI)1.20 * M Complex projects where the software is part of a strongly coupled complex of hardware, software, regulations and operational procedures.



COCOMO 81 was developed with the assumption that a waterfall process would be used and that all software would be developed from scratch.

Since its formulation, there have been many changes in software engineering practice and COCOMO 2 is designed to accommodate different approaches to software development.

COCOMO 2 models

COCOMO 2 incorporates a range of sub-models that produce increasingly detailed software estimates.

The sub-models in COCOMO 2 are:

  • Application composition model: Used when software is composed from existing parts.
  • Early design model: Used when requirements are available but design has not yet started.
  • Reuse model: Used to compute the effort of integrating reusable components.
  • Post-architecture model: Used once the system architecture has been designed and more information about the system is available.COCOMO Model

Fig: Use of COCOMO 2 models



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A Soon-to-be Computer Engineer by profession, he has profound devotion to add Data Scientist as a prefix to his name. He’s been to the nooks of the web (at least of the surface web) and planning to add some real figures in his pocket!

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