COCOMO Software Cost Estimator

Project Size

Estimated size 32 KLOC

Project Class

Cost Drivers

Team & process maturity (EAF) 1.00×

Schedule vs nominal (SCED) 100%

Estimate

Effort

— PM

Schedule

— mo

Average team size

— people

Organic — small, familiar

Semi-detached — mixed team

Embedded — tight constraints

How it works

This is the Constructive Cost Model (COCOMO), Barry Boehm's regression model for estimating software project effort from its size in thousands of lines of code (KLOC). The basic form is a power law:

Effort  E = a · KLOC^b        (person-months)
Schedule D = c · E0^d          (months, from nominal effort E0 = a·KLOC^b)
Staff    N = E / D             (average full-time engineers)

The exponent b is greater than 1 for every project class, which is why effort grows faster than size alone — coordination overhead compounds as a codebase grows (this is the same root cause Brooks's Law points at). The three curves plotted use Boehm's original coefficients:

Organic (a=2.4, b=1.05) — small team, familiar domain, flexible requirements.
Semi-detached (a=3.0, b=1.12) — mixed experience, moderate constraints.
Embedded (a=3.6, b=1.20) — tight hardware/regulatory constraints, high coordination cost.

The Effort Adjustment Factor (EAF) multiplies the nominal effort up or down for team capability, tooling and process maturity — Intermediate COCOMO derives it from 15 cost drivers; here it's collapsed into one slider. The schedule slider models the real, non-linear cost of compressing or stretching the calendar relative to the nominal schedule: compressing it below 100% adds coordination and rework overhead (more people join a late project without shortening it proportionally — Brooks's Law again), while stretching it too far adds its own drag from idle capacity and process churn. Both effects feed back into the effort and staffing readouts, and the marker on the active curve — plus the size of the animated team platform — update live as you drag.

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