In
viral marketing, the
K-factor can be used to describe the growth rate of websites,
apps, or a customer base. The formula is roughly as follows:
(e.g. if each new customer invites five friends, i = 5)
(e.g. if one in five invitees convert to new users, c = .2)![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!ARV6FUJ2JP&type=0&index=2383)