Unit economics for startups: checks before you invest

Growth can hide bad unit economics for a year or two. Then it makes them worse.

You can see Indian investors saying so with their cheques. Bain's India Venture Capital Report 2026, which put 2025 VC and growth investment at about $16 billion, describes consumer investors moving to higher-margin D2C brands and favouring "retention-led growth and disciplined unit economics". That's an investor's way of saying the old trade, growth now and margins later, stopped clearing. If you're still being pitched on it, you'll want the numbers underneath.

Unit economics sit inside two of the checks in our guide to evaluating early-stage startups: market sizing and client agreements. Here you'll get the formula sheet, the costs founders in India tend to leave out, and the questions that test the answers.

Why growth hides bad unit economics

Growth hides bad unit economics because new customers arrive faster than old ones leave, so total revenue rises even when each group of customers shrinks or loses money. Averages make it worse. A blended acquisition cost mixes cheap word-of-mouth customers with expensive paid ones, and you'll usually find the expensive ones are where the growth comes from.

You pay for it later. CB Insights studied 431 VC-backed companies that shut down since 2023. Running out of capital topped the list at 70%, but CB Insights calls that the final cause, not the root one, and 19% cited unsustainable unit economics. The set is global, with 47% of companies based outside the US, and the reasons come from post-mortems and shutdown notes, not audited data. Treat it as a pattern, not a measurement. You've probably seen it.

The unit economics formula sheet

Five formulas cover most early-stage companies: contribution per customer, gross margin, acquisition cost, payback and lifetime value. Ask the founder to fill each one in from their books, for the last 6 months, by channel where it applies. The formula's the easy part. What goes into it isn't, so you'll want to read the inputs line by line.

Measure	Formula	Ask
Contribution per customer	Revenue net of GST, minus discounts, delivery, payment fees, returns and variable support	Which costs sit below this line, and why?
Gross margin	(Net revenue minus cost to deliver) divided by net revenue	Is delivery staff counted here or in overheads?
CAC	All sales and marketing spend in a period divided by new paying customers in that period	Are salaries, agency fees and referral bonuses in?
Payback	CAC divided by monthly contribution per customer	How does it compare with runway?
Lifetime value	Monthly contribution multiplied by expected months a customer stays	Is "months retained" measured, or assumed?

A Sample, with illustrative numbers only: CAC of Rs 6,000 and monthly contribution of Rs 500 give a payback of 12 months. If customers stay 18 months on average, lifetime value is Rs 9,000, or 1.5 times CAC. That looks healthy until you notice the company has 8 months of cash. Then it doesn't. You're funding a gap.

Five checks before you trust the numbers

Before you trust a founder's unit economics, rebuild each input from the books yourself. Contribution should net out every variable cost. Acquisition cost should be fully loaded. Retention should come from cohorts. Payback should be read against runway. And all of it should agree with the monthly MIS and the filings behind it.

1. Contribution, after the Indian costs

Prices in India are often quoted inclusive of GST. Strip it out first. It was never the company's money, and you don't want to value a tax. Then take off payment gateway fees, discounts, delivery and, for consumer brands, the cash-on-delivery orders that travel to a pin code in Lucknow or Indore, sit at the door for a day and come back unpaid, with the courier charging both ways. These are the lines that tend to go missing.

2. Fully loaded CAC

Ad spend alone flatters. Don't accept it. Add the sales team's salaries, agency retainers, launch discounts, referral bonuses and the first month you gave away. Yes, that one too. All of it.

3. Cohorts, not averages

Ask for retention by the month customers joined. One table. That's all you need. If the September cohort keeps fewer customers after six months than the March cohort did, the product is getting worse at holding people, whatever the blended number says. Revenue won't show you that. Cohorts will, and you'll see it within a single page.

4. Payback against runway

Payback only matters in relation to the cash the company has left. In the Sample above, a 12-month payback would be comfortable with years of runway. With 8 months, it's dangerous.

5. Tie it to the MIS

Unit economics built in a pitch spreadsheet should reconcile with the monthly report. If they don't, you've found your first question. Our guide to reading a startup MIS shows how to tie revenue, collections and margin to GST returns and bank statements.

If each new customer costs more than they ever return, growth is a faster way to spend the round.

What to ask the founder this week

Send the founder the formula sheet before the next meeting and ask them to fill it in from their books, not their deck. How they fill it in tells you as much as what they write. A founder who knows these numbers cold, who can say what changed in October and why, has usually been running the company on them already. One who needs two weeks hasn't.

• Contribution per customer for the last 6 months, with every cost line shown.
• CAC by channel, fully loaded, month by month.
• Cohort retention by joining month.
• Payback in months, next to runway in months.
• What changes in each number if the next round comes in late.

Feed the answers into your view on valuation; a company that loses money on each customer is worth less at any growth rate. At MyStartupValley, our team evaluates each startup on six due diligence parameters: founder verification, market sizing, cap table, legal, client agreements and compliance. There are 5,000 founders from incubators at IITs, IIMs and accelerators running on MSV. To review evaluated companies with sector and stage fit, see the investor workspace.

Questions

What are unit economics for a startup?

Unit economics is what the company earns or loses on one unit of business, usually one customer or one order, after the costs of acquiring and serving it. The core measures are contribution per customer, customer acquisition cost, payback period and lifetime value.

What is a good CAC payback period for an early-stage startup?

There is no single right number; it depends on margins, retention and how much cash the company holds. A practical test is to compare payback in months with runway in months. If customers pay back their acquisition cost only after the cash would run out, growth deepens the hole.

Why can fast growth hide bad unit economics?

New customers arrive faster than old ones leave, so revenue rises even when each cohort shrinks. Blended acquisition cost also mixes cheap organic customers with expensive paid ones. Ask for cohort retention and acquisition cost by channel to see what growth is covering.

Sources: Bain & Company, India Venture Capital Report 2026, Apr 2026 · CB Insights, The top 9 reasons startups fail, 5 Mar 2026