The opening eBook of the Retention category. It explains why keeping customers is the cheapest growth a small business will ever find, what a retention experience actually looks like and how to build a simple system you can run without hiring anyone new.
Members ebook·7 chapters· 50 minute read
Chapter 1
Why Retention Is the Cheapest Growth You'll Ever Find
The plain numbers behind why keeping a customer beats winning a new one, and how to work out your own.
Most small business owners can tell you, roughly, what they spent on marketing last year. Far fewer can tell you, even roughly, how much they spent winning each new customer. And almost none can tell you what it would have cost to keep the customers they lost. That gap in the numbers is where retention quietly does its work, year after year, while everyone is busy looking somewhere else.
This chapter is about closing that gap. Not with a finance lecture, and not with the kind of formula that needs a spreadsheet you'll never update. With three numbers any owner can work out in an afternoon: what you spend to win a customer, what an average customer is worth over time and what it would cost you to keep one more.
Once you've seen those three numbers for your own business, the case for retention stops being a slogan from a marketing book. It becomes obvious. And it usually changes how you think about next month's marketing budget.
The full chapter walks through the three numbers in detail with a worked example for a service firm and a small online shop.
The three numbers that decide everything
There are three numbers worth knowing. None of them needs to be perfect. Rough is fine. The point is to have them in your head when you're making decisions about where to spend time and money next month.
The first number is your cost to win a customer. Add up everything you spent on marketing last year - paid ads, your website refresh, the freelancer who runs your social media, the directory listing, the printed flyers, the trade event fee. Divide that total by the number of new customers you won. That's your cost per new customer. For a service firm with a small Google Ads budget and one freelancer, it's often somewhere between £80 and £300. For a high-touch consultancy or a clinic, it can be £500 or more.
The second number is what an average customer is worth to you over the time they stay. Pick a typical customer. Add up everything they pay you in a year. Multiply by the number of years they tend to stay. For a plumbing firm with an annual maintenance contract at £240, with customers staying about four years, that's £960. For an online shop selling £40 items where buyers come back twice on average, it's £80. For a consultancy where a client pays £8,000 a year and stays three years, it's £24,000.
The third number is what it costs you to keep that customer for one more year. A check-in phone call. An email newsletter. A small loyalty perk. A thank-you note. A renewal reminder. For most small businesses, the per-customer cost of running a basic retention rhythm is under £20 a year, and often under £5.
Three numbers worth knowing this month
Cost to win one new customer (last year's marketing total divided by new customers won)
Lifetime value of an average customer (annual spend times typical years stayed)
Cost to keep one customer for an extra year (rough estimate of your retention activity per head)
What the gap actually means
Put the three numbers next to each other and the gap is usually startling. The plumbing firm spends maybe £150 to win a new customer, earns £960 from one over four years and spends about £8 a year on retention activity. The therapist spends £200 to win a new client, earns about £900 from a six-session package, spends maybe £5 to send a check-in email three months later. The consultancy spends £1,200 to win a new client, earns £24,000 over three years and spends a couple of hundred on the relationship in total.
In every case, the cost of keeping a customer is a tiny fraction of the cost of winning a new one. And every customer kept is a customer you don't have to spend the £150 or £200 or £1,200 to replace.
This is the case for retention in one paragraph. Marketing is renting attention. Retention is owning a relationship. The first one you pay for again every month. The second one pays you, quietly, year after year, with very little new spend.
A worked example: the plumbing firm
Take the plumbing firm from the worked examples in What is Go-to-Market?. Three vans, a small team, a tiered annual maintenance contract at £240 a year and a steady stream of emergency call-outs. Last year they spent £18,000 on marketing - Google Ads, a Google Business Profile manager, two letting agent partnerships, a small print run and a website refresh. They won 90 new contract customers.
Cost to win one new customer: £200. Lifetime value of an average customer (£240 a year, four years): £960. Cost of running a retention rhythm for a customer (one annual reminder email, one quarterly newsletter, one personal phone call halfway through the year): about £6 of staff time and software per customer per year.
Now imagine they could keep one extra customer in five from drifting away. That's eighteen extra customers retained, each worth £960 over four years. That's £17,280 of revenue that didn't need £200 of marketing spend behind it. The retention rhythm to make that happen costs maybe £540 a year. The return on that £540 is enormous, and the work is mostly things the business already knows how to do.
A worked example: the online shop
Now take an online shop selling handmade homewares. Average order value £45. Customers buy about twice a year on average and stay about two years. Lifetime value: £180. Last year they spent £12,000 on Facebook and Instagram ads, an email tool and a small influencer partnership. They won 600 new customers. Cost to win one new customer: £20.
The retention work here looks different. A monthly newsletter with new products, a thank-you note in every parcel, a small loyalty discount on second purchases, a re-engagement email three months after a customer goes quiet. Per-customer cost: maybe £1.50 a year.
If they could lift their average number of orders from two a year to two and a half, lifetime value goes from £180 to £225. Across 600 customers, that's £27,000 of extra revenue. Per-customer retention cost to do it: about £900 a year. The gap is, again, the kind of thing that ought to change next quarter's plan.
Why retention is so often neglected
Three reasons. The first is that retention work is invisible. New customers feel like progress. Existing customers feel like maintenance. There's no dopamine hit from sending a check-in email to someone who's been a customer for two years.
The second is that retention takes a quarter or two to show in the numbers. Marketing campaigns can be measured in days. Retention shows up six months later, when the customer renews, or buys again, or refers a friend. Owners running on the short loop never get round to it.
The third is that retention sits awkwardly between marketing, sales and operations. The marketing person doesn't think it's their job. The sales person has moved on to the next deal. Operations is busy delivering the work. Without an owner deciding it matters, no one picks it up.
What changes when retention becomes a habit
Three things change in the business once retention becomes part of the weekly rhythm rather than an afterthought. First, monthly revenue gets steadier. Renewals and repeat purchases smooth the spikes. Second, marketing spend gets calmer. You're not having to win the same number of new customers each month to stand still. Third, the relationships get warmer. Customers feel looked after, refer more freely and complain earlier when something is off, which gives you the chance to fix it.
None of this requires new software, new staff or a new strategy. It requires a few simple decisions and a willingness to keep them through the busy weeks. That's what the rest of the eBook is for.
What to do this week
Spend one hour working out your three numbers. Don't aim for accuracy to the pound. Aim for honesty to the order of magnitude. Write the three numbers on a single sheet of paper and put it where you'll see it. Cost to win a customer. Lifetime value. Cost to keep a customer for one more year. Once they're in front of you, the rest of the eBook will land harder.
The recurring principle here is the simplest in the whole series: keep existing customers close. The earlier eBook to revisit if you haven't is What is Go-to-Market?, which explains where retention sits in the six-piece map. The next chapter, The Retention Experience, takes the three numbers and turns them into a map of where retention is actually won or lost in your business.
The rest of this chapter walks through the practical steps, the templates and the checklists you need to put it into action. It includes worked examples, copy frameworks and the small decisions that make the difference between a plan that sits in a drive and one that gets used.
Inside you'll find a step-by-step playbook, a downloadable template, a checklist you can run this week and a short list of common mistakes to avoid before you start.
The full action plan, broken into weekly steps.
Ready-to-use scripts, templates and checklists.
Worked examples for different sized businesses.
Common mistakes and how to avoid them.
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