Unit Economics: Frequently Asked Questions

LTV measures the total gross profit expected from a customer over their entire relationship with your business. For SaaS: LTV = (ARPU × Gross Margin) ÷ Monthly Churn Rate. It tells you how much you can afford to spend acquiring each customer. Most companies overestimate LTV by using revenue instead of margin.

SaaS LTV = (Monthly ARPU × Gross Margin %) ÷ Monthly Churn Rate. Example: $100 ARPU, 75% margin, 3% monthly churn = $2,500 LTV. Always use gross margin, not revenue — this is the most common calculation error.

E-commerce LTV = Average Order Value × Purchase Frequency × Customer Lifespan × Gross Margin. Example: $65 AOV × 4 orders/year × 3 years × 40% margin = $312.

Use Contribution Margin LTV: (ARPU minus variable compute/token costs) ÷ Churn Rate. Standard LTV overstates AI company economics by 30-60% because it ignores GPU and API costs. If your variable costs exceed 15% of revenue, you need CM-LTV.

CAC = Total Sales & Marketing Expenses ÷ New Customers Acquired in the same period. Include everything: team salaries, ad spend, tools, agencies, content production, events, and overhead. Most founders undercount by 2-3x because they only include advertising.

A fully-loaded CAC includes: marketing team salaries, sales team salaries and commissions, all advertising spend, marketing and sales tools, agency and contractor fees, content production, events and sponsorships, and allocated overhead. Only counting ad spend gives you 'Performance CAC' — useful for channel optimization but dangerous for strategic decisions.

Use fully-loaded blended CAC: total S&M spend ÷ new customers. Don't try to precisely attribute. Investors respect founders who acknowledge 'our blended CAC is $X' over those who claim unrealistically low channel-specific numbers. Present the trend over time and show you understand all the inputs.

The widely-cited benchmark is 3:1 — $3 of lifetime value for every $1 spent on acquisition. Below 1:1 means you lose money per customer. But ratio alone is insufficient — it must be paired with payback period. A 4:1 ratio with 24-month payback can still bankrupt a cash-constrained company.

As a starting point, yes. But context matters enormously. PLG companies can be healthy at 2:1 with 3-month payback. Enterprise SaaS may need 5:1+ to justify long sales cycles. Bootstrapped companies should focus on payback period over ratio. The right target depends on your model, stage, and cash position.

Because ratio ignores timing. If your payback period is 24 months but you have 12 months of runway, you'll run out of cash before seeing returns — even with 'healthy' unit economics. This is why the LTV-CAC Operating System always pairs ratio with payback period.

The number of months to recover your customer acquisition cost. Formula: CAC ÷ (Monthly Revenue × Gross Margin). Benchmarks: bootstrapped <6 months, seed-funded <12, Series A 12-18, growth stage <24. For cash-constrained companies, payback period is more important than LTV:CAC ratio.

Largely yes. If your payback exceeds 6 months, you're financing customer acquisition from future revenue you may not survive to collect. Payback period is the single most important metric when cash is limited. LTV still matters for strategy — but payback determines survival.

A comprehensive framework by Lech Kaniuk for running a business on unit economics constraints — not just tracking them. It includes four proprietary frameworks (Value Driver Framework, LTV-CAC Growth Map, Stratification Model, Alignment Protocol), the Unit Economics Simulator, Impact Tables, and implementation playbooks. Detailed in 'The Two Numbers That Build or Break Every Business.'

The complete book on LTV-CAC mastery: 15 chapters covering foundation, frameworks, advanced analytics, alignment, and execution. Plus 4 proprietary frameworks, ready-to-use templates (executive dashboard, cohort tracker, payback calculator, quadrant planner), real case studies (OnlinePizza/Delivery Hero, SunRoof, B2B SaaS, D2C), and actionable worksheets.

Founders and CEOs who want profitable growth, not just fast growth. Marketing leaders who need to prove ROI. Product managers who want to build features that move retention and value. Finance teams who need real unit economics for planning. Investors evaluating company health. Anyone who makes decisions that affect customers or costs.

Lech Kaniuk is an entrepreneur, investor, and author who has raised €150M+ across 10+ companies. He was part of the early team at OnlinePizza (acquired by Delivery Hero), founded SunRoof (building-integrated solar), and founded FaradayX (energy-as-a-service). He is an angel investor and author of three business books including 'The Two Numbers That Build or Break Every Business.'