Startup Unit Economics — CAC and LTV (the ₹500 vs ₹2,000 Rule), Payback Period, Contribution Margin, Burn Rate and Runway, TAM/SAM/SOM Market Sizing That Investors Believe, MVP and Pivot Discipline, Bootstrapping vs Raising, and What 'Unicorn' Actually Means — the Numbers an Indian Founder Must Know Before the First Investor Meeting
Video Explanation & Insights
CAC ₹500 vs LTV ₹2,000 — the business secret revealed (Day 5 of the startup series)
8 videos on this topic
CAC, LTV and payback — the ₹500 vs ₹2,000 rule
Customer acquisition cost is the total sales and marketing spend in a period divided by the new customers won in it. Ramesh spends ₹50,000 on ads in a month and gains 100 customers: CAC is ₹500. Lifetime value is what a customer contributes in profit over the time they stay — if each customer yields ₹2,000 of gross profit before they leave, Ramesh earns four times what he spent and should spend more; if they yield ₹300, every new customer is a loss and the channel must change. The fixes the series lists — referrals, organic content, cutting channels that do not convert — all reduce CAC; raising prices, upselling and reducing churn raise LTV.
| Metric | Formula | Benchmark |
|---|---|---|
| CAC | (Sales + marketing spend, including salaries and tools) ÷ new customers acquired | Track by channel; blended CAC hides a bad channel |
| LTV | Average gross profit per customer per month × average customer lifetime (1 ÷ monthly churn) | LTV : CAC ≥ 3; > 5 suggests under-investment in growth |
| CAC payback | CAC ÷ monthly gross profit per customer | < 12 months for SaaS/subscriptions; consumer businesses aim lower |
| Contribution margin | Revenue − variable costs (COGS, payment gateway, delivery, discounts) per order or user | Positive from the first order; negative contribution cannot be fixed by scale |
| Churn / retention | Customers lost in a period ÷ customers at start; cohort retention curves | Retention drives LTV more than pricing |
Burn and runway — Day 6 in numbers
- •Gross burn: total monthly cash outflow. Net burn: outflow minus inflow (revenue). Runway: cash in bank ÷ net burn — ₹3 crore in the bank with ₹15 lakh of net burn is 20 months.
- •Raise at 18 months, not 6: a round takes 4–9 months from first meeting to money; investors read a short runway as weakness and price it.
- •Runway assumptions: build three cases (current burn, growth plan, cut plan) and know the month in which each hits zero; include GST/TDS liabilities and annual costs (insurance, audits, compliance) that lumpy cash flows hide.
- •Bootstrapping (Day 7's counterpoint): funding growth from revenue keeps 100% of equity and forces unit economics to work early; the trade-off is speed. Most Indian founders bootstrap to an MVP with paying users, then raise to scale a proven CAC/LTV.
- •MVP and pivot: the minimum product that tests the riskiest assumption with real customers; a pivot is a deliberate change of product, segment or channel when the cohort data says the current one will not reach LTV > CAC — decided on numbers, not on fatigue.
TAM, SAM, SOM — market sizing investors believe
| Layer | Meaning | How to compute |
|---|---|---|
| TAM — total addressable market | Everyone who could buy the category, everywhere | Top-down from industry reports is acceptable here; state the source |
| SAM — serviceable available market | The part your product and geography can serve today | Filter TAM by segment, geography, language, price point, channel |
| SOM — serviceable obtainable market | What you can realistically win in 3–5 years with your CAC and capacity | Bottom-up: customers you can acquire per month at your CAC × average revenue — the number the model must reconcile to |
What a unicorn is — and what the arithmetic implies
A unicorn is a privately held startup valued at USD 1 billion or more by its investors (about ₹8,000 crore or more at current rates); India has produced more than a hundred since 2011, concentrated in fintech, SaaS, e-commerce and logistics. The label is a valuation, not profit: the arithmetic behind it is a revenue multiple (say 10–20× ARR for high-growth SaaS) applied to a run-rate, which means a unicorn needs ₹400–800 crore of annual revenue growing fast, or a market position investors expect to get there. For a founder the practical lesson from Day 7 is that valuation follows unit economics and growth — a company with LTV:CAC of 4, payback under a year and a bottom-up SOM in the thousands of crores earns the multiple; one with a great TAM slide does not.
Unit economics: questions we are asked
All sales and marketing cost: ads, agency fees, sales salaries and commissions, tools, discounts used for acquisition; exclude retention spend.
Use cohort retention to project churn, apply gross margin per customer per month, and cap lifetime at 3–5 years; state the assumption in the model.
Only if there is a clear path (pricing, volume discounts, delivery density) to positive within the plan; investors will ask for the month it turns.
18–24 months to the next milestone that re-prices the company, plus a buffer for a slow market.
Banks lend on DSCR and security, but a DPR that shows CAC, LTV and contribution margin explains why the projections are credible.
Yes — unit-economics sheets, cohort LTV, burn/runway scenarios, TAM/SAM/SOM, projections, valuation reports and DPRs for investors and banks.