Blog PostsDigital FirstGrowth HackingHow to build a viral loop (using mathematics)

How to build a viral loop (using mathematics)

Let’s say you post a really funny cat video on YouTube.

You share your cat video across your social networks and you get your first 1,000 views. Out of these viewers, 10% (100 people) decides to share your cat video with their friends, once. Each share generates 11 new views of the video, a total of 1,100 views. Going from 1,000 views (1st cycle) to 1,100 new views (2nd cycle) equals a viral coefficient of 1,1.

And anything above 1,0 = viral, wohoo!

How many views will you get in the 3rd cycle? Out of the 1,100 people in the 2nd cycle, 10% will share it once generating on average 11 new views per share and — boom! — you get 1,210 (1,100 x viral coefficient) additional views after the 3rd cycle!

Well, look at your cat video now, mighty Viral Loop Designer!

But before we get ahead of ourselves, let’s examine the inner workings of viral math:

Specific viral loop weaknesses to watch out for

Why isn’t every spin doctor constantly involved in designing new viral loops? Well, as it turns out — it’s incredibly difficult to get them to work. Here are some important reasons why:

Population size

The first thing we must take into account is that your content can only be expected to perform as long as you can reach the right target audience. Cat videos have a very broad appeal across demographics, so your population size will be enormous!

But most businesses have very little to do with cats, of course. If you’re a B2B company promoting instruction videos for your CRM software, you’ll probably run right through your population size in just a couple of cycles. But maybe that’s good enough?

Loop instability

By calculating averages within each cycle, you might be able to find somewhat stable indications for click-through rates (CTR), conversion rates, social back traffic, and so on. But in reality, these indicators are incredibly unstable and they tend to fluctuate immensely from cycle to cycle.

Getting your 2nd cycle to perform above 1,0 (viral coefficient) is often a true challenge — and it generally doesn’t get easier with each cycle!

Influencer distribution

A key factor is social back traffic from people sharing your content. This average traffic number can be deceiving; most shares hardly result in any back traffic at all. It’s often influencer shares that keep the average up!

Influencers tend to interact more, so you’re likely to run out of influencer shares much more quickly than social shares from average users.

Cycle times

YouTube is very friendly to viral mechanics: You watch a short video, you share it, and the next cycle kicks in — often times in a matter of minutes. Actually, from a mathematical standpoint (see mathematical formula), cycle time actually matters more than social back traffic averages!

If you need someone to review a 30-page whitepaper on SlideShare, have them actually read and internalize it, and then tell their network to do the same, you could suddenly be facing an average cycle time of several hours (or even days). Simply put: Long cycle times makes everything much harder1.

External factors

Your cat video isn’t the only social object competing for people’s attention. It’s impossible to fully control or anticipate what content will compete for attention at any given time.

We’re dealing with chaos theory here: There are simply too many unknown variables to find, understand and compute, from the anatomy of complex networks down to the slightest of details affecting individual behavior.

Content production

Producing content that can inspire the kind of math discussed above is quite a challenge in itself. With unlimited marketing budgets, you might be able to enroll a team of world-class creatives with an organization of production professionals to match. But there are no guarantees.

Hundreds of thousands of talented (or lucky) people are launching attempts at viral content every day. Can you be sure to beat them all at a timing of your choosing?

Still hungry for viral success? What we want to is to apply the viral loop to business, right?

Economic considerations for a viral project

We could go on to create a “cat video”, meaning a video that’s cute and funny to a large number of people and thus aim for the same math as described above and, for the sake of argument, reach 1,000,000 views on YouTube. If the total production cost (including promotion costs) is $250,000 and the company’s average profit margin is $50 per unit sold, a 1,000,000 view video that converts new customers at 0,01% (not uncommon) will generate $5,000. Which, of course, is not great for a $250,000 video.

Also, if the business can manage 1,000,000 video views on YouTube, how can anyone be sure that everyone watching are potential customers — and nothing else? Obviously, there are other ways for a viral video to create value beyond direct sales:

  • Brand recognition,
  • audience growth,
  • employer branding,
  • data harvesting,
  • email activations,
  • and so on.

Still, “money in the bank” should always be an important consideration. And there’s always the chance that your viral mechanics fails.

Boosts for viral boops to consider

Basically, we’ll need all the help we can get. Let’s explore a quick overview of helpful viral tools:

Seed traffic. The 1st wave of traffic you generate, either by activating your existing audience, through influencer outreach, or advertising. (Must reach critical mass for the viral effects to be given a chance to come into effect.)

Landing page. A page designed specifically to harvest a specific intent. Typical for landing pages are that they only have one call-to-action (CTA).

Lead magnet. “Free” online content used to encourage potential customers to opt in. Efficient lead magnets target urgent needs that can be relieved quickly. (Also known as “optin bribes.”)

Uptick page. If you can get a person to take action, then you’ve “primed” them. So, instead of letting them go, you can refer them to an uptick page where you can make an additional ask of them.

Uptick bonus. Lead magnets that are specifically tailored for specific content types are often referred to as “content upgrades”.

Referral engine. Often combined with uptick pages, referral engines encourage users to share more than once, often using a generator for unique URL-addresses.

If you’re looking for ready-made tools, a place to start could be LeadPages with templates for high-converting landing pages. If you’re looking for uptick pages with built-in referral engines, check out UpViral.

How to engineer a viral loop (with mathemathics)

Let’s build an imaginary viral loop for the Doctor Spin blog, shall we?

Step 1. The seed traffic (some Facebook ads targeted at a lookalike audience based on existing email subscribers) is directed to a landing page. If your brand already has critical mass, that helps, too.

Step 2. The traffic is offered a “free” (in exchange for their email addresses) lead magnet (a three-day video course that targets an urgent pain point, like, “How to Succeed with Content Marketing in B2B”). Three consecutive videos allow for three separate uptick pages.

Step 3. At the 1st uptick page, the converted users get the first video and are incentivized to share my landing page by an uptick bonus (“Free Templates for Creating High-Converting Blog Posts and Landing Pages for B2B”). In this example, the user will get the bonus if he or she refers at least three friends to the initial landing page. A referral engine, generating unique URLs for each user, keeps track.

Step 4. On day two, I use their email addresses to remind all signups that the next video is live on the 2nd uptick page. Once there, they are reminded again to share for the uptick bonus.

Step 5. On day three, I once again remind the signups via email that the final video is live on the 3rd uptick page. Once there, they are reminded a third time to share for the uptick bonus.

For the sake of argument, let’s say that I send 1,000 potential customers to my lead page converting at 40%, in turn sending 400 people to the uptick pages converting at an average of 20%. The most active users like the videos and the uptick bonus (I hope!) enough to share them 1,5 times on average at a rate of 10 new landing page visitors per share.

  • 1st cycle: 1,000 targeted visitors, 400 new subscribers.
  • 2nd cycle: 1,200 targeted visitors, 480 new subscribers.
  • 3rd cycle: 1,440 targeted visitors, 576 new subscribers .

And so on!

No viral loop lasts forever, of course. But, hopefully, this theoretical experiment demonstrates the raw power of viral loops. By using a landing page, three separate uptick pages presented in sequence, an email reminder function, a referral engine with unique URLs, a lead magnet, and an uptick bonus, we increase our chances for better numbers.

When dealing with small population sizes (often for highly niched products or services), you often have to add the above type of complexity to sustain your viral loop.

My favorite viral loop is that of Instagram:

When you take a picture, Instagram allows you to edit and apply various filters to it. When you engage in this activity, you become creatively more attached to the picture — it becomes more than a picture; it becomes something that you’ve created. Obviously, social networks are viral specialists. It’s in their DNA, it’s their business to activate online users. Doing it yourself for your business can be daunting.

Even if you only manage to establish a viral coefficient of 0,5 (and only keep it for a few cycles), these conversions might still make a big difference to your initial marketing effort — remember the seed traffic?

If you use Facebook Ads to pay for 1,000 click-throughs, an added “0,5 loop” will increase your ROI for the initial ad buy considerably. There’s no such thing as “free traffic,” but this is close.

Example (“0,46” loop):

  • Seed traffic: 1,000 views
  • Lead page conversion: 32%
  • Uptick page traffic: 320
  • Uptick bonus conversion: 16%
  • No. of referrers: 51,2
  • Shares per referrer: 1,4
  • Total no. of shares: 71,68
  • Social back traffic per referral: 6,5
  • 1st cycle traffic: 465,2 views (“free traffic”)
  • Viral coefficient: 0,46

In reality, for your type of business, transforming an existing “0,5 loop” into a “1,1 loop” might just be near impossible, (and crazy expensive). However, adding “0,5 loops” here and there might, in fact, be easy and cost-efficient — while doubling your marketing ROI. So, in essence, the viral effect shouldn’t be seen as a binary phenomenon. Instead of thinking of a “0,5 loop” that breaks after three cycles as a failed viral loop, you could regard it as an online marketing amplifier.

Not bad for a funny cat video.

Photo by Oliver Hale on Unsplash.


  1. “Reducing viral loop cycle time has by far and away the greatest effect on viral growth.” (Source.)


Avatar of Jerry Silfwer
Jerry Silfwer
Jerry Silfwer, aka Doctor Spin, is an awarded senior adviser specialising in public relations and digital strategy. Currently CEO at KIX Communication Index and Spin Factory. Before that, he worked at Kaufmann, Whispr Group, Springtime PR, and Spotlight PR. Based in Stockholm, Sweden.

Grab a free subscription before you go.

Get notified of new blog posts & new PR courses

🔒 Please read my integrity- and cookie policy.

The silent switch is disrupting our societies. Algorithms reward sensationalism over brand loyalty and trust — and society must suffer the consequences.
Most popular