LTV:CAC ratio measures customer lifetime value divided by customer acquisition cost—the fundamental unit economics determining whether a business model works or burns cash toward death.
Formula Breakdown
LTV (Lifetime Value): Average revenue per customer over their entire relationship.
Formula: ARPU (average revenue per user) / Churn Rate
Example: $50/month ARPU, 5% monthly churn = $50 / 0.05 = $1,000 LTV
CAC (Customer Acquisition Cost): Total sales/marketing spend divided by new customers acquired.
Example: Spend $50K on ads, acquire 500 customers = $100 CAC
LTV:CAC Ratio: $1,000 LTV / $100 CAC = 10:1 ratio
Benchmark Ratios
3:1 = Healthy: Customer generates 3x what you spent acquiring them. Room for growth and profitability.
1:1 = Death Spiral: Breaking even on acquisition. Unsustainable—burns cash faster than generating value.
5:1+ = Under-Investing: Could spend more on acquisition and accelerate growth. Often means competition will outspend you.
David Skok’s SaaS Metrics 2.0 (2012) established 3:1 as the gold standard, with <12 months CAC payback period ideal.
Real-World Examples
Slack (2015-2019): ~10:1 ratio via freemium virality. Low CAC (organic team invites), high LTV ($100+/month/team).
Uber (2015-2019): <1:1 ratio—subsidized rides, driver incentives. Burned billions before achieving profitability.
Netflix (2020): ~3-4:1 ratio—content spend as “CAC,” $15/month ARPU, churn ~2-3%/month.
Consumer Subscriptions: Struggled with 1-2:1 ratios—HelloFresh, Blue Apron, Stitch Fix all faced LTV:CAC compression.
Improving the Ratio
Increase LTV:
- Reduce churn (better onboarding, customer success)
- Increase ARPU (upsells, annual plans, premium tiers)
- Extend customer lifetime (build switching costs, integrations)
Decrease CAC:
- Optimize ad spend (better targeting, creative testing)
- Build organic channels (SEO, content, word-of-mouth)
- Referral programs (Dropbox’s storage-for-invites model)
- Product-led growth (free tier → paid conversions)
Misleading Metrics
Gross vs Net LTV: Needed to factor in COGS (costs of goods sold), not just revenue. Dropbox’s storage costs, marketplace take-rates all reduce net LTV.
Blended CAC: Mixing organic (free) and paid acquisition inflated ratios. Separated channels revealed truth.
Time Value of Money: Payback in 36 months ≠ payback in 3 months. Needed to discount future cash flows.
2021 ZIRP Distortion
Zero interest rates made LTV:CAC math irrelevant—VCs funded “grow at all costs,” ratio be damned. Companies with 0.5:1 ratios raised billions (WeWork, MoviePass). 2022-2023 correction forced discipline: “path to profitability” = fixing unit economics.
Source: David Skok SaaS Metrics LTV:CAC