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COCOMO® 81 is a model that allows one to estimate the cost, effort, and schedule when planning a new software development activity, according to software development practices that were commonly used in the 1970s through the 1980s. It exists in three forms, each one offering greater detail and accuracy the further along one is in the project planning and design process. Listed by increasing fidelity, these forms are called Basic, Intermediate, and Detailed COCOMO®. However, only the Intermediate form has been implemented by USC in a calibrated software tool.

The implemented tool provides cost, effort, and schedule point estimates. It also allows a planner to easily perform "what if" scenario exploration, by quickly demonstrating the effect adjusting requirements, resources, and staffing might have on predicted costs and schedules (e.g., for risk management or job bidding purposes). Over 63 data points in the COCOMO® 81 calibration database, the Intermediate form demonstrates an accuracy of within 20% of actuals 68% of the time for effort, and within 20% of actuals 58% of the time for a nonincremental development schedule.

COCOMO® 81 has a rich legacy. Originally published by Dr. Barry Boehm in 1981 under the simple name COCOMO®, it went on to become (and arguably remains) the most widely used software project cost estimation model throughout the world. It has also existed in other incarnations, the most prominent being Ada COCOMO®. After nearly twenty years of solid service, however, it is finally being retired in favor of COCOMO® II, which models the way software is built today in the 1990s, and will continue to be built well into the new century.


Boehm, Barry W., Software Engineering Economics, Prentice Hall, 1981.

This book is still the most complete resource for information regarding original COCOMO®, as well as providing a wealth of material that will improve one's understanding and application of COCOMO® II.

For questions regarding COCOMO® 81, please contact Brad Clark.