The Mechanics of Unit Economics
Why LTV/CAC is the single most important ratio tracked automatically by every sophisticated software venture fund.
LTV: The Lifetime Value Engine
If you charge $30/month, and the average customer physically stays for identically 20 months before churning, their Gross LTV is $600. However, software requires AWS server logic and customer support logic to maintain that user. Net LTV explicitly factors in Gross Margin, ensuring you only measure the absolute pure profit the user generates before they abandon you.
CAC: Customer Acquisition Cost
This explicitly calculates total marketing spend (Ads, SEO) entirely divided by new users. If you spend $10,000 on Facebook, and exactly 200 users click through and put in credit cards, your CAC is exactly $50 to "buy" a human.
The Holy 3:1 Ratio
If it costs $50 to buy a customer, and they mathematically generate $400 over their lifetime, your ratio is 8.0x. This is an infinitely printable money machine. You should aggressively borrow millions of dollars in debt strictly to pour into Facebook ads.
If it costs you $50 to buy a customer, but they cancel instantly on month two ($60 generated), and your server costs eat $20 of that... your Net LTV is $40. Your ratio is 0.8x. You physically bleed $10 every single time a user signs up. The business is fundamentally bankrupt at a unit level.