LTV:CAC Ratio for Ecommerce: Formula, Calculator, Benchmarks

The LTV:CAC ratio compares what a customer is worth to you with what it cost to win them. If the average customer brings in 150 over their lifetime and it costs 45 in marketing to acquire one, your LTV:CAC ratio is about 3.3 to 1.

It answers the question every growing store eventually asks: can we afford to spend more to get customers? A ratio comfortably above 1 means each new customer pays back more than they cost. A ratio below 1 means growth is losing you money.

Most guides to LTV:CAC are written for subscription software companies. Ecommerce works differently, and some of the standard advice will mislead you if you apply it to a store. This guide covers the ecommerce version.

The LTV:CAC formula

LTV:CAC ratio = customer lifetime value ÷ customer acquisition cost

Customer lifetime value (LTV) is the total a customer spends with you across all their orders. See how to calculate customer lifetime value in Shopify for three ways to work it out.

Customer acquisition cost (CAC) is your marketing spend divided by the number of new customers you acquired in the same period:

CAC = marketing spend ÷ new customers acquired

If you spent 9,000 on marketing last quarter and gained 200 new customers, your CAC is 45.

LTV:CAC calculator

Customer lifetime value

Customer acquisition cost

3.3 : 1

At or above 3:1, the usual sign of a healthy, scalable business.

What is a good LTV:CAC ratio?

The most commonly cited target is 3:1. As Harvard Business School's Christina Wallace puts it, an LTV-to-CAC ratio of three or higher is attractive and indicates a scalable business.

Below 1:1: each new customer costs more than they are worth.
1:1 to 3:1: you are probably growing at the expense of profit.
Around 3:1 or higher: generally healthy.
Well above 5:1: often a sign you could spend more on acquisition and grow faster.

Treat those numbers with care for ecommerce, for the reasons below.

Three ecommerce mistakes that make LTV:CAC misleading

1. Using revenue instead of profit for LTV

The 3:1 rule of thumb comes from software businesses, where gross margins are often 70% to 80%, so revenue and profit are close. A store with 40% gross margins is in a very different position. A revenue-based LTV of 150 is only 60 of gross profit, and against a CAC of 45 the real ratio is closer to 1.3:1, not 3.3:1.

If you can, calculate LTV on gross profit (revenue minus product costs, and ideally shipping and refunds too). If you only have revenue, aim for a much higher ratio than 3:1.

2. Counting all customers instead of new ones in CAC

CAC should divide spend by new customers only. Dividing by all customers who ordered, including repeat buyers who would have come back anyway, makes CAC look far cheaper than it is.

Be clear too about whether you are using blended CAC (all marketing spend ÷ all new customers, including those who found you organically) or paid CAC (paid media spend ÷ customers who came from paid channels). Blended CAC is easier to calculate and harder to argue with. Paid CAC is more useful for deciding ad budgets but depends on attribution.

3. Mixing up historical and predicted LTV

LTV can mean what customers have actually spent so far (historical) or what you expect them to spend over their whole life (predicted). Historical LTV is real but understates the value of recent customers who have not finished buying. Predicted LTV covers the full life but is an estimate.

A practical approach for stores: compare CAC against the actual revenue or profit a customer cohort generated in its first 6 or 12 months. That tells you your payback period, how long it takes for a new customer to cover what it cost to acquire them, which is often more useful day to day than the lifetime ratio.

How to improve your LTV:CAC ratio

Raise LTV:

Improve your repeat purchase rate with post-purchase emails timed to when customers usually reorder.
Increase average order value with bundles and free-shipping thresholds.
Win back customers who have gone quiet before they are lost for good.

Lower CAC:

Move budget away from campaigns that mostly reach existing customers.
Grow channels with little or no direct cost, such as search, email signups and referrals.
Improve conversion rate so the same ad spend produces more first orders.

Getting LTV:CAC from your own data

LTV:CAC is hard to calculate by hand because the inputs live in different places: lifetime value in your store data, spend in each ad account, and new customer counts in yet another report.

If you connect your store and ad accounts to Ask AI, your AI assistant can bring them together. Ask AI reports historical lifetime value, including the median so a few big spenders do not skew it, and LTV by cohort at months 1, 3, 6 and 12. It puts that next to spend from Meta Ads and Google Ads and your new customer counts. If an input is missing, for example no ad account is connected, it tells you rather than guessing. You can ask:

"What's my blended CAC for the last quarter, and how does it compare to 12-month LTV?"
"How long does it take a new customer to pay back their acquisition cost?"
"Show me LTV at 3, 6 and 12 months for each monthly cohort this year."

It works in Claude, ChatGPT, Gemini and Perplexity, and you can try the live demo without an account.

FAQ

What is the LTV:CAC ratio?

Customer lifetime value divided by customer acquisition cost. It shows how much value a customer brings in for every unit of money spent acquiring them.

What is a good LTV to CAC ratio?

3:1 is the commonly cited target. For ecommerce, calculate LTV on gross profit if you can. With a revenue-based LTV, you need a much higher ratio to be profitable.

How do you calculate CAC for an ecommerce store?

Divide marketing spend by the number of new customers acquired in the same period. Count new customers only, not everyone who ordered.

What does an LTV:CAC ratio below 1 mean?

Each new customer costs more to acquire than they are worth, so growth is losing money until LTV rises or CAC falls.