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Customer acquisition cost calculator: CAC, payback and LTV:CAC for online stores

· Nolyn research team

Enter what you spent on marketing in a period and how many new customers it brought. The calculator gives your customer acquisition cost (CAC), then checks it against what a customer is worth: the profit on their first order, how many orders it takes to pay back the CAC, their lifetime value (LTV), the LTV:CAC ratio and the most you can pay to keep a 3:1 ratio. It is built for e-commerce: margin per order, not SaaS subscription revenue. Everything runs in your browser.

How do you calculate customer acquisition cost?

CAC = total marketing spend ÷ new customers. $2,400 of ads plus $600 of other marketing that brings 100 new customers is a CAC of $30.00 ($24.00 from ads alone). On a $40 order with a 50% margin you keep $20.00, so the first order loses $10.00 and the CAC pays back after 1.5 orders. A customer who orders 2.5 times is worth $50.00 in profit: an LTV:CAC of 1.67:1, below the usual 3:1 target, which allows a CAC of $16.67.

Calculate your customer acquisition cost

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Meta, Google, TikTok, Amazon and marketplace ads: everything you paid to ad platforms.

Agency and freelancer fees, influencer gifts and fees, tools, content and the marketing share of salaries. Enter 0 for ads-only CAC.

First-time buyers only. Repeat orders from existing customers are not acquisitions.

Revenue per order, after discounts and before tax.

What is left of the order after product cost, shipping, packaging and marketplace or payment fees. The same margin the break-even ROAS calculator uses.

Including the first. 1 if customers rarely come back; check your store's repeat rate for a real figure.

Customer acquisition cost (CAC)
$30.00
CAC from ad spend only
$24.00
Profit per order before marketing
$20.00
First-order profit after CAC
-$10.00
Orders to pay back the CAC
1.5
Customer lifetime value (profit)
$50.00
LTV:CAC ratio
1.67:1
Most you can pay for 3:1 LTV:CAC
$16.67
Break-even ROAS on one order
2x

The first order does not cover the CAC; you only make money if customers come back. That works for products people reorder, not for one-off purchases.

The LTV:CAC ratio is under 3:1, the common rule of thumb that leaves room for overheads. Profitable, but with a thin cushion.

Margin too thin to pay for customers? Check the market price

A higher price is often the cheapest way to afford a CAC. Nolyn compares your competitors' current prices, deals and ratings on Amazon US in one table, with a pricing suggestion. Sign-in required; new accounts get 100 credits.

Compare competitor prices

The CAC formula, and what to put in it

Customer acquisition cost = marketing spend in a period ÷ new customers acquired in the same period. The two choices that change the number are what counts as spend and what counts as a new customer.

Spend: ad spend is the minimum. A blended CAC adds what else it took to win those customers: agency or freelancer fees, influencer fees and product gifts, email and design tools, and the share of salaries spent on marketing. In the example, ads alone give $24.00 per customer and the blended figure is $30.00, a quarter more.

Customers: count first-time buyers only. Dividing by all orders, repeat orders included, makes CAC look lower than it is. If you sell on a marketplace and cannot see who is new, CAC is closer to a cost per order; use the ROAS calculators instead.

Is your CAC too high? LTV:CAC by orders per customer

A CAC is only high or low against what the customer brings back. With a $40 order and a 50% margin, each order leaves $20.00 before marketing. At a $30.00 CAC, this is how the ratio moves with repeat purchases:

  • Below 1:1, customers never pay back what they cost.
  • Between 1:1 and 3:1, the business is profitable per customer but has little left for rent, salaries and returns.
  • Above 3:1 is the usual target. Well above it can mean you are underspending on growth.
Orders per customerLifetime profit (LTV)LTV:CAC at $30.00Max CAC for 3:1
1$20.000.67:1$6.67
1.5$30.001:1$10.00
2.5$50.001.67:1$16.67
4$80.002.67:1$26.67
6$120.004:1$40.00

$40 average order, 50% margin before marketing. LTV here is lifetime profit, not revenue: using revenue would inflate the ratio by 1 ÷ margin, twice in this case.

Marketplace fees are an acquisition cost too

On a marketplace, part of the fee pays for the buyer the marketplace brought you. Etsy makes that explicit with Offsite Ads: on a sale that came from Etsy's ads off Etsy, it charges 15% of the item price plus shipping (12% once a shop passes $10,000 a year), capped at $100 per order. On a $25 item with $5 shipping that is $4.50, paid only when the sale happens (Etsy's Fees & Payments Policy, last updated October 5, 2026).

Your own store flips that. The same $30 order on Shopify Basic with Shopify Payments costs $1.17 in card fees (2.9% + 30¢), against $3.30 in regular Etsy fees, but every buyer is one you paid to bring. The $2.13 you save per order is your acquisition budget per order before the $39 monthly plan; a $30 CAC on a single-order customer wipes it out many times over. We compare the four platforms order by order in Shopify vs Etsy.

CAC, CPA and ROAS: which number to use

CPA (cost per acquisition) in ad platforms is ad spend ÷ conversions, usually orders, new and returning. CAC is all marketing spend ÷ new customers. ROAS is ad revenue ÷ ad spend. They answer different questions: ROAS and CPA judge a campaign, CAC judges whether growth pays.

They meet at break-even: with a 50% margin, an ad that brings a $40 order breaks even at a ROAS of 2.00, which is a cost of $20.00 per order. Work out your own with the break-even ROAS calculator, and check live campaigns with the ROAS calculator. If your margin is too thin for any of this, start from the price with the markup calculator.

How to use the CAC calculator

  1. Pick a period

    A month or a quarter; spend and new customers must come from the same period.

  2. Enter spend and new customers

    Ad spend, other marketing costs and the number of first-time buyers.

  3. Add order value, margin and repeat orders

    Margin after product cost, shipping and fees; orders per customer over their lifetime.

  4. Read CAC against LTV

    Check the first-order profit, the payback in orders and whether LTV:CAC reaches 3:1.

Questions

What is the formula for customer acquisition cost?

CAC = total marketing spend ÷ number of new customers in the same period. $3,000 of marketing that brings 100 new customers is a CAC of $30.

What is a good CAC for e-commerce?

There is no single number: a good CAC is one your customers pay back. The usual test is an LTV:CAC ratio of at least 3:1, with LTV measured as lifetime profit. A $40 order with a 50% margin, bought 2.5 times, supports a CAC of up to $16.67.

Should CAC include salaries and tools?

For a blended CAC, yes: the marketing share of salaries, agency fees, influencer costs and tools. Track paid CAC (ad spend only) as well, since that is the part you can turn up or down day to day.

What is the difference between CAC and CPA?

CPA is what ad platforms report: ad spend divided by conversions, which can include repeat customers. CAC divides all marketing spend by new customers only, so it is usually higher.

How is CAC payback calculated?

Payback in orders = CAC ÷ profit per order. A $30 CAC and $20 of profit per order pay back after 1.5 orders. Divide by orders per month to get months.

How do I lower my customer acquisition cost?

Raise conversion rate on the traffic you already pay for, cut ad sets whose CPA is above your maximum, lean on channels where you pay per sale (marketplace ads, affiliates) and win repeat orders, which spread one CAC over more profit.

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