This calculator is for store operators who buy customers with paid ads and want to know whether that trade is actually worth making. It multiplies average order value, gross margin, purchase frequency and customer lifespan into a lifetime value figure, then divides by your customer acquisition cost to produce the LTV to CAC ratio. If you run subscriptions, consumables or any catalog with repeat purchases, this is the single most decision-relevant number in your reporting.
The ecommerce twist is that both sides of the ratio are easy to flatter. LTV gets inflated when it is built on revenue instead of margin, when returns are ignored, or when a handful of loyal outliers drag the average up. CAC gets understated when it only counts ad spend and skips agency fees, creative production and discounts given to first-time buyers. This tool forces the margin correction on the LTV side; the honesty on the CAC side is up to your inputs.
Why it matters: the ratio sets your growth budget. A store whose customers pay back a healthy multiple of their acquisition cost can afford to bid aggressively and grow. A store at one to one is renting revenue from the ad platforms. Knowing which one you are changes every downstream decision, from ad budgets to how much to invest in retention.
LTV:CAC ratio calculator
This LTV uses gross-profit contribution, not raw revenue, so the ratio reflects money you actually keep.
Enter your average order value, gross margin, how often a customer buys, how long they stay and what it costs to acquire them. The calculator returns customer lifetime value on a gross-profit basis and the LTV to CAC ratio, which tells you how much profit each acquisition dollar brings back.
How this is calculated
ltv = aov * gross_margin * orders_per_year * lifespan_years
ltv_cac_ratio = ltv / cac
cac_payback_orders = cac / (aov * gross_margin)This uses gross-profit LTV, multiplying order value by margin before applying frequency and lifespan. Using revenue instead of margin would overstate the ratio, because it ignores the cost of the goods.
Worked example: a store with a 60.00 average order, 40 percent margin, three orders a year and a two-year lifespan earns 60 times 0.40 times 3 times 2, or 144.00 in gross-profit LTV. Against a 50.00 CAC that is a 2.88:1 ratio, and payback lands after roughly 2.1 orders.
How to read the result
Read the ratio together with the payback figure, not alone. A 3:1 ratio that takes two years to collect still ties up cash the whole time, and ad platforms bill monthly while customers pay you back slowly. Fast payback with a modest ratio is often a healthier position for a small store than a glamorous ratio with a long collection period, because it lets you recycle the same acquisition budget more times per year.
Also remember the output is an average. New stores should treat the lifespan input with suspicion, since a store that is eighteen months old cannot actually know its two-year retention. Where possible, run the calculation separately per acquisition channel and per first product purchased; blended averages routinely hide one channel doing all the profitable work.
Benchmarks: reading your ratio
The 3:1 guideline is the most widely used rule of thumb: three dollars of lifetime gross profit per acquisition dollar generally leaves enough after overhead to make paid growth sustainable. Once overhead, returns and the softer costs of acquisition are counted, ratios below roughly 1.5:1 usually mean the store is losing money on each new customer, and anything at or below 1:1 is losing money before overhead even enters the picture.
A very high ratio, say 6:1 or more, reads as a win but often signals underinvestment in growth: acquisition spend so cautious that the store is leaving profitable customers unclaimed for competitors. These thresholds are practitioner conventions, not laws, and they assume an honest, fully loaded CAC. Hit the guideline with a flattered CAC and you have only benchmarked your own bookkeeping.
Frequently asked questions
What is the LTV:CAC ratio?
It compares the gross profit a customer generates over their lifetime to what it cost to acquire them, making it the exchange rate between marketing spend and long-run profit. Unlike ROAS, which stops at the first purchase, it credits every later order back to the acquisition dollar that started the relationship.
Should LTV use revenue or profit?
Gross profit, always. The revenue version answers a different question, how much cash a customer moves through the store, which is useful for forecasting but dangerous for acquisition decisions. Ad budgets are paid out of margin, so the ratio that guides them has to be built on margin too.
What is CAC payback?
It is how many orders, or how long, it takes for a customer’s gross profit to repay their acquisition cost. Shorter payback frees up cash to reinvest in the next customer sooner.
How do I lower CAC or raise LTV?
Lower CAC by improving targeting, creative and conversion rate so the same spend buys more customers. Raise LTV by lifting average order value, margin, repeat purchase rate or retention length, each of which feeds directly into the formula above.
Verdict
Compute this ratio per channel with a fully loaded CAC and a margin-based LTV, and let it set your acquisition budget rather than the other way round. The frequency and lifespan inputs come straight out of cohort reporting, which is exactly what the platforms in our ecommerce analytics tools roundup are built to surface. And since the cheapest way to raise the ratio is keeping the customers you already paid for, the AI support chatbots we compared are a direct lever on the LTV side.
