CAC vs LTV: How to Know If Customer Acquisition Is Profitable
Compare customer acquisition cost with revenue and contribution lifetime value, then estimate payback before scaling a channel.
CAC tells you what it costs to win a new customer; LTV estimates what that customer is worth over time. Compare CAC with contribution-margin LTV, not revenue LTV alone, and check how quickly the customer pays back.
CAC and LTV answer different questions
Customer acquisition cost (CAC) answers: what did we spend to acquire one new customer? Lifetime value (LTV) answers: how much value can that customer create across the relationship? Neither metric is a complete decision on its own.
The useful comparison is not a generic benchmark. It is your acquisition cost against the contribution margin that remains after product, fulfillment, payment and other variable costs. Use a cohort when you want to know whether customers acquired in the same period are paying back; use a blended ratio only for a quick business snapshot.
The formulas: revenue LTV is not contribution LTV
| Metric | Formula | What it is good for |
|---|---|---|
| CAC | Sales + marketing spend ÷ new customers | Cost of winning a first-time customer |
| Revenue LTV | AOV × total orders per customer | Top-line customer value estimate |
| Contribution LTV | AOV × total orders × contribution margin | Margin-aware profitability planning |
| LTV:CAC | Contribution LTV ÷ CAC | A directional efficiency ratio |
| Payback orders | CAC ÷ (AOV × contribution margin) | How many orders recover acquisition cost |
| Payback period | The time until cumulative contribution reaches CAC | How quickly acquisition spend is recovered |
| Cash payback | Payback period adjusted for payout, inventory and refund timing | Whether the model can be funded in real cash |
Illustrative cohort: 100 customers acquired together
This is an illustrative cohort model, not EshopPick customer data. Assume $5,000 of acquisition spend buys 100 new customers, so CAC is $50. Each customer makes one first order plus 1.5 repeat orders over six months. AOV is $60 and contribution margin is 50%.
The cohort generates 250 total orders and $15,000 of revenue. Contribution LTV is $75 per customer, or $7,500 for the cohort; LTV:CAC is 1.5× before fixed costs. The revenue LTV of $150 per customer is not the cash available to repay CAC.
| Timing | Orders | Revenue | Contribution at 50% | Cumulative contribution − $5,000 CAC |
|---|---|---|---|---|
| Month 0 | 100 first orders | $6,000 | $3,000 | −$2,000 |
| Month 3 | 75 repeat orders | $4,500 | $2,250 | +$250 |
| Month 6 | 75 repeat orders | $4,500 | $2,250 | +$2,500 |
| Total | 250 orders | $15,000 | $7,500 | +$2,500 |
Test CAC payback before you scale acquisition
This planning model uses contribution margin, repeat-order timing and a customer cohort. It is more conservative than revenue LTV.
AOV × contribution margin sensitivity
Each cell shows contribution LTV:CAC / estimated payback months, holding repeat orders and CAC constant.
| AOV ↓ / margin → | 40% | 50% | 60% |
|---|---|---|---|
| $48 | 0.96× / 6.42 mo | 1.2× / 4.33 mo | 1.44× / 2.94 mo |
| $60 | 1.2× / 4.33 mo | 1.5× / 2.67 mo | 1.8× / 1.56 mo |
| $72 | 1.44× / 2.94 mo | 1.8× / 1.56 mo | 2.16× / 0.63 mo |
Repeat-purchase sensitivity
Cash payback is an estimate, not a cash-flow statement: it assumes the first order happens immediately, repeat orders arrive evenly, and contribution is collected when the order is paid. Add payment payout lag, inventory purchases and refund timing before committing a large budget.
Revenue payback is not the same as cash payback
The cohort reaches contribution payback during the second order in the illustrative schedule: the first 100 orders produce $3,000 of contribution, and the first repeat wave takes cumulative contribution above the $5,000 acquisition cost. That is an estimated month-three payback, not a promise that cash is available on that exact date.
Cash recovery can be later when inventory is purchased before the sale, payment processors settle after the order, refunds arrive after acquisition spend or contribution is calculated before taxes and fixed overhead. Add those timing effects to a cash-flow model before scaling a channel that has a slow payback.
| View | Result in this example | Decision use |
|---|---|---|
| Revenue LTV | $150 per customer | Shows top-line relationship value, not profit |
| Contribution LTV | $75 per customer | Shows value available after variable costs |
| Payback orders | 1.67 orders | The first order alone does not recover $50 CAC |
| Estimated payback period | About 3 months | Depends on the repeat-order schedule |
| Cash payback | Later or earlier than the estimate | Reconcile payout, inventory and refund timing |
Sensitivity analysis: AOV, repeat rate and margin
There is no single LTV:CAC answer when AOV, repeat behavior or contribution margin can change. The interactive model below lets you change all three and see both contribution LTV:CAC and estimated cash payback. Its main grid changes AOV and margin together; the repeat-purchase cards show how retention changes the result.
Use conservative inputs first. If the result only works at a high AOV, a perfect margin or an unproven repeat rate, treat the channel as an experiment rather than a scalable acquisition engine.
Use CAC and LTV to choose the next action
- High CAC, healthy retention: improve creative, targeting, landing-page conversion or offer economics before cutting the channel.
- Low CAC, weak repeat purchase: inspect customer quality, onboarding, product experience and post-purchase retention.
- Healthy ratio, slow payback: check cash constraints; an attractive long-run model can still be hard to fund.
- Healthy revenue LTV, weak contribution LTV: review COGS, shipping, fees, refunds, discounts and the definition of margin.
Common mistakes
| Mistake | Why it breaks the decision |
|---|---|
| Using all customers instead of new customers for CAC | Returning customers make acquisition look cheaper than it was. |
| Mixing periods | Spend, customers and orders no longer describe the same cohort or window. |
| Using revenue LTV as profit | COGS, shipping, fees and refunds still have to be paid. |
| Treating a ratio as a guarantee | Cohorts, retention timing and channel quality change over time. |
Use the free tools
CAC + LTV Calculator
Calculate customer acquisition cost, revenue LTV, contribution LTV, payback orders and the LTV:CAC ratio from your own numbers.
Open toolAOV Calculator
Calculate average order value, items per order, average item price, conversion rate, revenue per visitor and the impact of an AOV lift.
Open toolContribution Margin
Calculate contribution margin per order, margin percentage, profit after fixed costs and break-even orders after COGS, fulfillment, fees and ad spend.
Open toolEcommerce Profit
Estimate ecommerce revenue, variable costs, net profit, profit margin, ROI and break-even orders from your own product and marketing inputs. Free with editable assumptions.
Open toolBreak-Even ROAS
Calculate break-even ROAS and CPA for ecommerce campaigns using product cost, shipping, fees and ad spend. Free, instant and no signup.
Open toolReferences and methodology
We use primary documentation where available and treat calculators as planning aids, not guarantees. Check the linked source when a platform changes its rules.
- Shopify: Customer acquisition cost
CAC definition, included acquisition costs and LTV comparison. Checked August 4, 2026.
- Shopify: What is a good LTV:CAC ratio?
High-authority context for the LTV:CAC relationship. Checked August 4, 2026.
- Google Analytics: Lifetime value
Official Analytics context for lifetime-value measurement. Checked August 4, 2026.
Turn this answer into a repeatable growth workflow.
Use the free result as your starting point, then move the next campaign, creative or growth decision into GrowthGPT when the work becomes repetitive.