How to Calculate the Viral Co-Efficient For Your App

If your app is not growing with more users then you haven’t figured out your viral co-efficient properly. After reading this blog post, hopefully that will change. There’s no better long-term growth for your app than viral growth! It’s not luck, it’s some smart math and teamwork to get it done. Chances are you either don’t what a viral co-efficient is, you don’t know how to calculate it, or maybe you have a good idea but just want to see exactly how we did it and get some insights or tips to help you out. It doesn’t matter what type of business you own online, the viral co-efficient can make you or break you.

Before we get into it and just incase you didn’t know this, focusing on getting your viral co-efficient right, in my opinion, is the most important thing your mobile app startup can do for long-term growth. I dare you to challenge me with another strategy or technique that is more valuable then a viral co-efficient that brings in free long term users. I will send you a $50 gift card of your choice and make it publicly known if you have a better strategy. Email me anytime at monty at bumpn .com – let’s do this!

First, what is the viral co-efficient (K)?

To keep it simple, it’s a number that tells you how many new users each of your existing users are bringing in to install your app. So if you have a K value of 0.5 that means for each user you currently have, half a new user is coming in and downloading the app… and no half-people don’t count :p On the other hand, if your K value is 1.5 (which would be amazing) then for every existing user, a new user and a half is downloading and installing your app.


Say you currently have 1000 users for your app that you have acquired through friends, family, social media, paid, word of mouth or any other means and you want to calculate your Viral Co-efficient.


The basic formula is K = i x c where “K” is the viral co-efficient, “i” is the number of invites and “c” is the conversion ratio.

We know that K is the number we need, so let’s figure out what “i” is first. Depending on what kind of data you are collecting and what in-app analytics tool you’re using, you would need to gather this information from data. Find out how many invites have been sent out total. Invites can be text messages sent from within the app to friends, an email sent from within the app or any other means of inviting users like a QR code. Unfortunately, other means of “invites” like word of mouth don’t count here since we can’t collect that data. For this example, let’s say that each users on average is inviting 12 people. Therefore, the total number of invites is 1200.

So far, K = 1200 x c.

Next, let’s get the conversion ratio. If 1200 invites got sent out, what % of that turned into installs? For this example, let’s say 10%.

So now we have K = 1200 x 0.1
K = 1.2

With a K value of 1.2 you have viral growth! Anything over 1.0 is viral growth and you can be assured that you’re on the right track with this and can improve it by increasing your conversion rate or making it even easier to invite more friends.

Now, if you’ve read this far, then that’s awesome and you’re learning so here’s the deal. If you only calculate the above (let’s say once a week) then it’s a good start but there is something even more important that I will get into next.

Viral Cycle Time

This is the length of time it takes to complete 1 cycle from invite to install which typically goes like this.

User first sees the app -> decided to try out the app -> decided they like the app enough to invite friends (or given incentive to do so) -> sends invites -> friend receives invitation -> friend installs the app.

How long does it take in your app to complete this cycle? Here’s the secret… the shorter time it takes to complete it then faster you will see viral growth. In other words, make it as friction-less as possible to invite friends!

Think of Youtube as an example. Visitor lands on a video page, he or she loves the video and decides to share it, clicks the share button below and voila, just like that it has been shared to their fb or twitter.

You will have to work with your development team closely to make sure how this is positioned inside your app is done and integrated and now that you know this, go out and make it happen! Leave me your comments below and let’s start making apps go viral!

Viral Coefficient

I'm a Family man and Entrepreneur. bumpn is my latest start-up which I am the Co-Founder and VP of Marketing. I believe in abundance and sharing value to everyone I can reach. I love tech, mobile and marketing. Follow this blog, or find me on FB or Instagram to learn from all the crazy stuff I'm part of and of course help you along your journey!