What is the LTV:CAC ratio?
The LTV:CAC ratio compares how much a customer is worth (lifetime value) to how much it costs to acquire them (customer acquisition cost). It's the clearest single read on whether your growth engine is sustainable, which is why investors ask for it first.
LTV:CAC = Lifetime value ÷ Acquisition cost
If a customer is worth $900 in gross profit over their lifetime and costs $300 to acquire, your ratio is 900 ÷ 300 = 3:1.
How to calculate LTV:CAC (step by step)
- Calculate LTV (gross profit basis) — use the customer lifetime value calculator to get gross-profit LTV, not revenue LTV.
- Calculate fully-loaded CAC — include all sales and marketing costs divided by new customers in the same period. Use the CAC calculator for the full breakdown.
- Divide LTV by CAC — that's your ratio.
Always use gross-profit LTV, not revenue LTV. A customer who generates $2,000 in revenue at 30% margin has $600 in LTV — not $2,000. Plugging revenue LTV into the ratio inflates it and hides real unit economics problems.
Worked example: B2B SaaS startup
A SaaS company tracking Q1 numbers:
| Metric | Value | Source |
|---|---|---|
| Monthly revenue per customer (MRR) | $100 | Billing data |
| Gross margin | 80% | Hosting + support cost |
| Average customer lifetime | 36 months | Churn = ~2.8%/mo |
| Revenue LTV | $3,600 | $100 × 36 |
| Gross-profit LTV | $2,880 | $3,600 × 80% |
| Total sales + marketing spend (Q1) | $180,000 | All-in cost |
| New customers acquired (Q1) | 250 | |
| Fully-loaded CAC | $720 | $180,000 ÷ 250 |
| LTV:CAC ratio | 4.0:1 | $2,880 ÷ $720 |
At 4.0:1, the business is in the healthy zone — each dollar spent on acquisition returns about $4 in lifetime gross profit. The company can confidently scale paid acquisition.
Danger zone example: ratio under 1:1
Same company but with lower retention and higher acquisition cost:
| Metric | Revised value |
|---|---|
| Gross-profit LTV | $900 (12-month lifespan) |
| CAC | $1,200 (expensive paid channels, low close rate) |
| LTV:CAC ratio | 0.75:1 |
At 0.75:1, the company loses $300 on every new customer before overhead. No amount of volume fixes this — scaling just burns cash faster. The fix: raise LTV (improve retention, upsell, raise prices), lower CAC (improve conversion, find cheaper channels), or both.
What's a healthy ratio?
The widely cited rule is 3:1: every $1 spent on acquisition should return about $3 in lifetime gross profit. Read the bands like this:
- Below 1:1 — you lose money on every customer. Unsustainable. Stop scaling and fix unit economics immediately.
- 1:1 to 3:1 — acquisition is too expensive or LTV is too low; fix before scaling. Some early-stage companies operate here temporarily.
- 3:1 to 5:1 — the healthy zone most SaaS and ecommerce businesses target. Sustainable growth.
- Above 5:1 — great efficiency, but often a sign you're under-investing and could grow faster by spending more on acquisition. Investors may push you to increase spend.
How to improve your LTV:CAC ratio
The ratio has only two levers — raise LTV or lower CAC. Specific plays that move the needle:
- Raise LTV: improve retention with better onboarding and customer success, introduce upsells and cross-sells, raise prices on proven value, and target higher-quality customer segments that stay longer.
- Lower CAC: improve conversion rate (same traffic, more customers), improve CTR to lower effective CPC, automate sales processes, and shift budget toward higher-intent channels.
Pair with your marketing budget and ROAS to connect customer-level economics to your overall ad spend.