How to use the viral reach calculator
Platforms do not publish how many people see a share, nor how many of them join. This calculator therefore invents no spread rate: all five values are your inputs, and the math is a plain arithmetic chain. Take shares per person, reach per share and the conversion rate from your own account insights or a past campaign. If those numbers are guesses, so is the result.
The core figure is the viral coefficient K = shares per person ร reach per share ร conversion rate. K is how many next-generation participants one participant brings in, so K of 1 or more means each generation holds or grows and the loop sustains itself, while K below 1 shrinks every generation and converges. For K below 1 the theoretical ceiling, starting participants รท (1 โ K), is shown alongside.
Because K at or above 1 grows without bound, generations are capped at 10, and the result labels say so when the cap is applied. Each row is a rounded whole number and the cumulative column is the sum of those rounded figures, so the on-screen numbers add up. In practice the same people are reached repeatedly and interest fades, so real spread usually falls short of the table.
Frequently asked questions
In the formula, yes. In reality K drifts down as the same people are reached again and the audience runs out. Use it to judge early-generation speed, not for long-range forecasts.
You have to derive it yourself, dividing a post's reach by its share or repost count in the platform's insights. No major platform reports the reach of a single share directly.