🦠 Contagious Illness Spread Estimator
Estimate how a contagious illness could spread over several transmission generations, given a starting number of cases and a reproduction number.
How disease spread is modeled
A simple way to model early-stage contagious illness spread is to assume each infected person passes the illness to a roughly constant number of new people, called the reproduction number (R0), across each transmission generation.
The formula used
This calculator uses the standard exponential growth approximation: Projected Cases = Initial Cases × R0^Number of Generations, capped at the total population size since spread cannot exceed everyone available to infect.
Real-world outbreaks are affected by immunity, behavior changes, interventions, and population mixing patterns that this simplified model does not capture, so results should be treated as a rough educational illustration rather than a public health forecast. This tool is for general educational purposes only.