# Customer acquisition cost for ecommerce Source: https://wearecrank.com/insights/customer-acquisition-cost-ecommerce How to work out customer acquisition cost for an ecommerce shop: the formula, the difference between blended and paid CAC, and how to judge whether your figure is good enough. --- [![Crank - Providing your levers for growth](/images/crank-logo-full.png)![](/images/crank-icon.png)](/) [Book a live demo](/contact?enquiry=live-demo)[Chat now](https://wa.me/447457416922?text=Help%20my%20business) Guide · Ecommerce reporting # Customer acquisition cost for ecommerce **Crank** Updated 3 November 2026 · 3 minute read The short answer Customer acquisition cost (CAC) is what you spend to win one new customer: the cost of acquiring customers divided by the number of new customers in the same period. Work out a blended figure across everything, and a paid figure for ads alone, and count new customers only. A good figure is one your margin can afford, so judge it against profit per customer, not against other shops. ## The formula CAC = acquisition cost ÷ new customers Both numbers must cover the same period, and the customers must be new ones. The cost is what you spent to win customers. At minimum that is ad spend. A fuller version also includes agency fees, creative, tools and staff time. Pick one definition and keep to it, so the figure can be compared month to month. ## Blended and paid CAC ### Blended CAC All acquisition cost divided by all new customers, whatever brought them. It includes customers who found you through search, email or word of mouth. ### Paid CAC Ad spend divided by the new customers your ads can be shown to have brought. Meta and Google each claim their own, and the claims often add up to more than you had. Keep both. Blended is the more honest figure for the business. Paid tells you which ads to keep and which to stop. If paid CAC looks good but blended keeps rising, the ads may be claiming customers who would have bought anyway. ## Where the figure goes wrong ### Counting repeat orders A returning customer is not an acquisition. Count first orders only, or CAC looks better than it is. ### Using the ad platform's own count Platforms report what they claim, and short tracking undercounts. Check against orders in Shopify. ### Mismatched periods A big spend this week and the sales it causes next week sit in different periods. Use longer windows to smooth it out. ### Leaving costs out If fees, creative and tools are missing, the figure is lower than the real one. ### Mixing in discounts A discount that wins a customer is a cost too. Keep an eye on what each new customer was offered. ## What counts as a good figure There is no figure that is good for every shop, because margins and repeat buying differ so much. Judge yours against what a customer is worth to you. Profit on the first order, after product cost, delivery and discount. How much more a typical customer spends over the following months. How long you can wait to get your acquisition cost back. Whether the figure holds when you spend more, or climbs. A CAC that your margin can pay back is fine, even if it looks high. One that your margin cannot is a problem, even if it looks low. The guide on [ecommerce customer acquisition](/insights/ecommerce-growth-strategies/ecommerce-customer-acquisition) covers ways to bring it down. ## Seeing it every day Working this out by hand once a month is slow, and the answer is old by the time you have it. The [trading dashboard](/crank-os/dashboards/trading) in Crank OS shows spend, revenue and return by channel, campaign and cohort every morning, using sales counted from your shop. The [ecommerce page](/crank-os/ecommerce) shows the whole set-up, starting with server-side tracking so the sales your ads made are counted. ## Questions ### Is CAC the same as cost per purchase? No. Cost per purchase counts every order. CAC counts only new customers, so it is usually higher. ### Should I include my own time? If you want the true cost of acquiring customers, yes. At minimum, state which costs you included, and stay consistent. ### What is the difference between CAC and ROAS? ROAS is revenue per pound of ad spend, for any order. CAC is cost per new customer. You need both to see whether growth is profitable. ### Why does CAC rise when I spend more? The easiest customers are reached first. More spend reaches people who are less likely to buy, so each costs more. ## Read next [PageTrading dashboard](/crank-os/dashboards/trading) [PageCrank OS for ecommerce](/crank-os/ecommerce) [GuideEcommerce customer acquisition](/insights/ecommerce-growth-strategies/ecommerce-customer-acquisition) ## Want to see spend and return every morning? Book a live demo with the Crank team, and see the trading dashboard with demo data. [Book a live demo](/contact?enquiry=live-demo)[Message us on WhatsApp](https://wa.me/447457416922?text=I%27d%20like%20a%20live%20demo%20of%20Crank%20OS)[See the trading dashboard](/crank-os/dashboards/trading)