Below is the viral coefficient calculator.  Remember that your marketing campaigns must have a viral coefficient greater than 1 for true viral growth.  This calculator uses members and invites as the viral metrics.

You could replace the concept of members with guest if you are using this for an event, or customers/clients if you are building a database of leads.  You could also easily replace the concept of “invites sent” with “shares” or “retweets” and the concept of invites accepted with “new friends” or “new followers”.  The idea of calculating a viral referral loop is the same in just about all use cases.

For a detailed example of how to use this viral coefficient calculator, read the article titled The Science of Going Viral Broken Down into One Simple Formula.