viral coefficient

Definition

The number of new users each existing user generates through referrals, where anything above 1.0 means exponential growth. It's the mathematical expression of every marketer's fantasy: growth that doesn't require advertising.

Example Usage

Our viral coefficient is 0.3, meaning each user brings in 0.3 new users, which is technically viral if you redefine all the words.

Origin

Borrowed from epidemiology and adapted for startup growth metrics in the mid-2000s

Fun Fact

Hotmail achieved a viral coefficient above 1.0 by simply adding 'P.S. I love you. Get your free email at Hotmail' to every sent message, acquiring 12 million users in 18 months.

Source: Growth marketing and viral marketing terminology

Related Terms

Intermediate

dwell time

The duration someone actually pays attention to an ad, especially in out-of-home or digital contexts. The uncomfortable metric that reveals most people ignore your billboard in 0.3 seconds.

📣 Marketing / Advertising

Intermediate

takeover

A high-impact ad buy where a brand dominates all advertising placements on a website, app, or platform for a set period. The digital equivalent of a hostile acquisition, but temporary.

📣 Marketing / Advertising

Advanced

cathedral building

Long-term brand-building activities that won't show measurable results for months or years, requiring faith that someone will eventually care. The opposite of performance marketing's instant gratification.

📣 Marketing / Advertising

Beginner

Bounce Rate

The percentage of visitors who land on your website and immediately leave, like someone who walks into a party, sees their ex, and moonwalks right back out the door. A high bounce rate is your website's way of telling you it has the personality of a damp towel.

📣 Marketing / Advertising

Beginner

the fold

The visible portion of a webpage or email before users have to scroll down. The prime real estate where your most important content lives or dies.

📣 Marketing / Advertising

Intermediate

ownable

A brand attribute, message, or positioning unique enough that competitors can't easily copy it. The marketing equivalent of a defensible moat, but made of adjectives.

📣 Marketing / Advertising

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