The Social K-factor: Tracking Viral Growth in a Social World

Tracking Viral Growth in a Social World

A product (or service) that grows by itself, driven by its customers who bring in more customers is considered to be “going viral.” While few products are inherently viral, marketers have used viral marketing techniques to establish their brands and create awareness about their products. The growth of Hotmail in the late ’90s is one of the first instances of a viral product (both sender and recipient need to use the product) and a viral marketing campaign (the default email signature inviting recipients to get their own free account). Social media is a great example of a viral product. There are several recent success stories in viral marketing — Old Spice, ALS Ice Bucket Challenge, Evian Roller Babies — the list goes on.

So, how do you measure the success of a viral marketing campaign? This is where the K-factor, a term borrowed from epidemiology comes in.

The K-factor: No Longer Adequate

The K-Factor formula needs an update

The concept of viral marketing is very well established, and is the Holy Grail that every marketer aspires to achieve. In this context, marketers track their “K-factor” — a measure of the growth rate of their customer base. It also applies to the growth rate of websites, apps, and marketing campaigns. It is defined as:

k = i * c


  • i = the number of invites sent by each customer
  • c = the number of “conversions”, i.e., the number of invitees that respond

As you can see from this formula, a product (or website or app or marketing campaign) is “viral” or growing exponentially if its k-factor is greater than 1. The higher the k-factor, the faster the growth.

Social Media and Viral Marketing

Today, social media is an integral part of any viral marketing campaign. Marketers makes extensive use of Facebook, LinkedIn, Twitter, Instagram, and Pinterest, to name a few, to execute their campaigns. The ubiquitous “share” (or “like”) button that manifests on social media and on websites is the starting point of the viral effect. But what makes social media interesting is that it is an inherently viral product. Unlike the one-to-many nature of traditional media (such as television and even the pre-social-media era websites), social media is a truly one-to-many-to-many (-and-ongoing) platform.

This makes the traditional definition of the K-factor archaic, because now it is no longer about just invites and conversion. Invitees have many more ways to interact with the messages such as likes and shares that will not count as a conversion in the traditional sense. It’s time for an update to the definition of the K-factor.

Introducing the “Social K-factor”

The Social K-factor is a composite measure that describes the velocity of your content on social media. It depends on two key variables:

  • The Social Coefficient, which is a measure of the quality of your content, the social networks on which your content is shared, and the social influence of the sharers on these networks
  • The Sharing Ratio, which is a measure of the popularity of your content and the likelihood of it being shared.

The Social Coefficient is a function of three factors:

  • The number of Posts (i.e. Shares) on social media channels
  • The number of Clicks resulting from these Posts
  • The number of Interactions from these Posts, which includes:
  • likes /favorites
  • shares/retweets, and
  • comments on those shares

The Social Coefficient is a function of the above variables and can be defined as

s = fn (P, Cl, In)


  • P = # of Posts
  • Cl = # of clicks
  • In = # of Interactions

The Social K-factor formula is defined as:

ks = s * c


  • c = the sharing ratio — rate at which visitors share a page, and
  • s = the Social Coefficient

While the semantics of the K-factor remain largely the same, this formula adjusts for the effects of social media and is a more accurate reflection of the way content propagates on the social web.

This is the first in a series of posts about how the Social K-factor can be improved by adding frictionless and organic sharing for your content website. In future posts, we will explore a more formal definition of the Social K-factor as well as tips and techniques to improve your Social K-factor.

To learn more about the Social K-factor, click here.

To learn more about Smart Share, click here