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Unit Economics

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Unit Economics

The direct revenues and costs associated with a particular business model, expressed on a per-unit basis. Understanding unit economics is essential to knowing whether a business can be profitable at scale — and a failure to get them right contributes to 37% of startup deaths (cash-related failures).

Key Metrics

Customer Acquisition Cost (CAC)

Total sales and marketing spend divided by number of new customers acquired. Includes ad spend, sales salaries, tools, and overhead.

Lifetime Value (LTV)

Total revenue expected from a customer over their entire relationship. For subscription businesses: average revenue per month × average customer lifespan in months.

LTV:CAC Ratio

The fundamental health metric:

  • <1:1 — Losing money on every customer. Unsustainable.
  • 1:1 to 3:1 — Marginal. May work with improvements.
  • >3:1 — Healthy. Standard target for SaaS businesses.
  • >5:1 — Potentially under-investing in growth.

Payback Period

Time to recover CAC from a customer’s revenue. Altman’s guidance: recover within 3 months for low-LTV products. Shorter payback = less cash needed to grow.

Gross Margin

Revenue minus cost of goods sold, per unit. High gross margins (>70%) allow reinvestment in growth; low margins (<40%) make scaling painful.

Why Unit Economics Kill Startups

“We’ll make it up in volume” is almost never true. If you lose money on each transaction, selling more just accelerates the loss. Common traps:

  • Subsidizing each transaction to acquire users (ride-sharing price wars)
  • Free tiers that cost more to serve than they convert
  • Sales cycles that cost more than the deal is worth
  • High churn that destroys LTV

When to Focus on Unit Economics

  • Pre-PMF: Unit economics can be negative — you’re still searching. But track them.
  • Post-PMF: Must trend toward profitability. Investors expect a path to positive unit economics by Series A/B.
  • At scale: Must be solidly positive. “Ramen profitability” (Altman) — enough revenue to sustain founders — is the first milestone.

See Also

Sources

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