COCOMO consists of a hierarchy of three increasingly detailed and accurate forms. Any of the three forms can be adopted according to our requirements. These are types of COCOMO model:

1. Basic COCOMO Model
2. Intermediate COCOMO Model
3. Detailed COCOMO Model

Basic COCOMO can be used for quick and slightly rough calculations of Software Costs. Its accuracy is somewhat restricted due to the absence of sufficient factor considerations.

Intermediate COCOMO takes these Cost Drivers into account and Detailed COCOMO additionally accounts for the influence of individual project phases, i.e in case of Detailed it accounts for both these cost drivers and also calculations are performed phase-wise henceforth producing a more accurate result.

Design
Effort : 16% to 18%
Time : 19% to 38%

Plan / Requirements
EFFORT : 6% to 8%
DEVELOPMENT TIME : 10% to 40%

Programming
Effort : 48% to 68%
Time : 24% to 64%

Integration & Test
Effort : 16% to 34%
Time : 18% to 34%

% depend on mode & size

In general, people prefer the functional size of software indicated as Function Point for one very important reason, i.e, the size expressed using the Function point metric stays constant in any case and whichever language or languages are used.