Basic COCOMO

This is a simple on-line cost model for estimating the number of person-months required to develop software. The model also estimates the development schedule in months and produces an effort and schedule distribution by major phases. This model is based on Barry Boehm's Constructive Cost Model (COCOMO). This is the top-level model, Basic COCOMO, which is applicable to the large majority of software projects.

Here is what Boehm says about the model: "Basic COCOMO is good for rough order of magnitude estimates of software costs, but its accuracy is necessarily limited because of its lack of factors to account for differences in hardware constraints, personnel quality and experience, use of modern tools and techniques, and other project attributes known to have a significant influence on costs." For more detailed information about COCOMO and software cost estimating in general, I strongly recommend reading Software Engineering Economics (1981), by Barry Boehm.

A number of additional COCOMO resources are available on the web.

The model estimates cost using one of three different development modes: organic, semidetached and embedded. Here is a summary of how Boehm describes the modes:

Organic

In the organic mode, relatively small software teams develop software in a highly familiar, in-house environment. Most people connected with the project have extensive experience in working with related systems within the organization, and have a thorough understanding of how the system under development will contribute to the organizations objectives. Very few organic-mode projects have developed products with more than 50 thousand delivered source instructions (KDSI).

Semidetached

The semidetached mode of software development represents an intermediate stage between the organic and embedded modes. "Intermediate" may mean either of two things:

1. An intermediate level of project characteristic.
2. A mixture of the organic and embedded mode characteristics.

The size range of a semidetached mode product generally extends up to 300 KDSI.

Embedded

The major distinguishing factor of an embedded-mode software project is a need to operate within tight constraints. The product must operate within (is embedded in) a strongly coupled complex of hardware, software, regulations, and operational procedures, such as an electronic funds transfer system or an air traffic control system.

Note. These models are provided as educational examples of technology developed and used by cost engineers. Use at your own risk. These tools are written in JavaScript and require a browser with JavaScript capability. If you have trouble viewing or using these tools, please consult the frequently asked questions.

Other COCOMO links:

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• COCOMO II - This program is an implementation of the 1981 COCOMO Intermediate Model. It predicts software development effort, schedule and effort distribution. It is available for SunOS or MS Windows and can be downloaded for free. The COCOMO II model is an update of COCOMO 1981 to address software development practice's in the 1990's and 2000's.
• COCOPRO implements Boehm's COCOMO technique for estimating costs of software projects. It supports the intermediate COCOMO model, and allows automatic calibration of the model to a cost history database.
• COOLSoft uses a hybrid of intermediate and detailed versions of COCOMO. This allows for the reuse of existing code, development of new code, the purchase and integration of third party code, and hardware integration.
• Costar is a software cost estimation tool based on COCOMO. A software project manager can use Costar to produce estimates of a project's duration, staffing levels, effort, and cost. Costar is an interactive tool that permits managers to make trade-offs and experiment with what-if analyses to arrive at the optimal project plan.
• Revised Intermediate COCOMO (REVIC) is available for downloading from the US Air Force Cost Analysis Agency (AFCAA).
• TAMU COCOMO is an on-line version of COCOMO from Texas A&M University.

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• COCOMO Software Cost Model
• Cost Estimating Guidelines
• Cost Spreading Calculator
• DSN Cost Estimating Cost Model
• Expendable Launch Vehicles - International
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• NASA/Air Force Cost Model (NAFCOM)
• Space Operations Cost Model (SOCM)
• Spacecraft/Vehicle Level Cost Model