Last Updated on November 10, 2026
Ask a UK business owner what a new customer costs them and most will quote their ad spend. That is not the number. The number is everything you spend to win customers, divided by the customers you actually won.
The usual mistake is only counting the ads. The agency fee, the directory listing, the time someone spends quoting: it all belongs in the acquisition bill. Count half the costs and your marketing looks twice as good as it is.
This calculator works out your cost per enquiry, your enquiry-to-customer rate and your customer acquisition cost, and compares the result with what a customer is worth to you.
No email address, no sign-up. Everything runs in your browser and nothing you type is sent anywhere.
How the sums work
- Total acquisition spend = ad spend plus other marketing costs plus sales costs.
- Cost per enquiry = total spend divided by enquiries.
- Enquiry to customer rate = customers divided by enquiries.
- Customer acquisition cost (CAC) = total spend divided by new customers.
Worked example, as an illustration: a business spends £1,500 on ads and £300 on an agency in a month, and that produces 40 enquiries and 8 new customers. Total spend is £1,800. Cost per enquiry is £45. The enquiry-to-customer rate is 20%. The acquisition cost is £225 per customer. If a first customer is worth £700 in gross profit, every £1 spent on acquisition returns £3.11.
The comparison at the end is the part that matters. An acquisition cost means nothing on its own. £225 to win a £700 customer is a working machine. £225 to win a £150 customer is a slow leak, unless repeat business reliably covers the gap, and you should know by how much rather than hope.
What this does not tell you
- It blends everything into one average. If you run several channels, the average can hide one channel doing all the work. Our attribution guide covers splitting it.
- Customer value here is first-customer gross profit, which is deliberately conservative. Loyal repeat customers raise the true value, but only measured repeat business should be counted, not assumed repeat business.
- One month can mislead. A quiet month overstates your CAC, a lucky one flatters it. Use a typical period or a three-month average.
Who this is for
Any business that spends money to win customers and has never divided one number by the other. If you cannot fill in the enquiries and customers boxes, that is itself the finding: start counting enquiries this week, because every marketing decision gets easier once you have that number.
Questions people ask
What counts as acquisition spend?
Everything that exists to win new customers: ads, agency and freelancer fees, directories, marketing tools, content costs, and the honestly costed time spent quoting and following up. Rent and insurance do not belong; they are overheads, not acquisition.
What is a good customer acquisition cost in the UK?
There is no universal good number, and anyone quoting one is guessing. The honest test is arithmetic, not benchmarks: your CAC against what a customer is actually worth to you in gross profit. Below £1 returned per £1 spent, acquisition is losing money on first business.
Should I include my own time?
Yes, if winning customers takes your hours, cost them at what that labour is worth. Free founder time is the most common hidden subsidy in small business marketing.
Is my data stored?
No. The calculation runs in your browser. Nothing you type is sent anywhere.
- Marketing ROI calculator: the same logic run against gross margin.
- UK marketing budget planner: set the spend side deliberately.
- The ROI test every marketing channel must pass.
- If you can’t measure it, don’t fund it.
