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Mobius
Intermediate

What is retention

Also known as: customer retention, user retention

Definition

Retention is the share of customers who keep buying or using your product over a set period, counting only those you already had at the start.

Why it matters

Keeping a customer usually costs less than finding a new one, because you already paid to win them.

Common mistakes

Counting new customers as retained, so a business that is losing regulars still looks stable.

Related terms

Worked exampleIllustration

Counting the regulars

Illustrative: a fictional cosmetics clinic, no real business. On 1 January it has 200 clients who visited in the last quarter.

  1. Start

    Clients on 1 January, all of whom visited in the last quarter.

    200

  2. New

    New clients who came for the first time between January and March, all with a visit in March.

    60

  3. End

    Clients with a visit in March, the 60 new ones among them.

    180

  4. Wrong formula

    Dividing everyone at the end by the start counts the newcomers as retained.

    180 ÷ 200 = 90%

  5. Right formula

    Take the newcomers out first, then divide by the start.

    (180 − 60) ÷ 200 = 60%

New clients hid 80 regulars who stopped coming.

Illustration

The leaky bucket

200 regulars on 1 January. new clients: 60. regulars who stopped coming: 80. 180 clients in March.180+60⁨new clients⁩−80⁨regulars⁩⁨who stopped⁩⁨coming⁩⁨200 regulars⁩⁨on 1 January⁩

Wrong: everyone at the end ÷ start

180 ÷ 200 = 90%

Right: take the new clients out first

(180 − 60) ÷ 200 = 60%

The wrong formula says 90% and looks healthy. Take out the 60 new clients and only 60% of the regulars stayed: 80 stopped coming.

Illustrative: a fictional clinic's quarter. Pouring in new clients refills the bucket and flatters the wrong formula, but it never closes the leak. Only keeping regulars raises the right number.

Does the curve stop falling?

Month 5: 35 of 100 still come. The curve stops falling from month 4, so those who stay are the regulars.100500012345⁨Months since the first visit⁩⁨100 new clients⁩⁨The early drop⁩⁨35 of 100 still here⁩

Month 5: 35 of 100 still come. The curve stops falling from month 4, so those who stay are the regulars.

Illustrative: 100 new clients of a fictional clinic in January, counted each month. The drop comes early, then the curve flattens. The flat part is your regulars.

Definition

Retention measures how many of the customers you had at the start of a period are still buying or using at its end. New customers who arrived during the period are left out, because counting them would hide the ones you lost. The usual formula, as HubSpot gives it, takes the customers at the end of the period, subtracts the new customers added during it and divides by the customers at the start. In a business without logins, retention is repeat visits or repeat purchases, counted from the booking diary, the invoice book or the WhatsApp Business chat list. Over time it is best read by cohort: group customers by the month they first came, and follow each group.

Why it matters

A business that looks only at its total number of customers can miss the regulars it loses, since new customers fill the gap for a while. The cohort curve tells the real story: when it stops falling and flattens, a core of customers has found lasting value, one of the signs of product-market fit. When it keeps falling toward zero, more advertising only refills a leaking bucket.

Directly related: Activation, Onboarding, Churn.

Formula

Retention Rate = ((Customers at end of period - New customers during period) / Customers at start of period) * 100

Improvement tips

  • Group customers by the month they first came, and follow what share of each group is still coming.
  • Call or write to regulars who stopped coming and ask what changed, before you offer anything.
  • Set the time window by how often people naturally buy: weeks for a café, months for a clinic, a year for an accountant.

Common mistakes

  • Measuring retention by a light action, such as opening a message, instead of a repeat visit or purchase.
  • Answering a drop in retention with discounts before finding out why customers left.

Related terms

ProductIntermediate

Activation

Activation is the moment a new customer first gets the result they came for, such as a first booking kept, and an early sign of who will come back.

ProductBeginner

Onboarding

Onboarding is the guided path a new customer takes from first contact to the first real result, such as a first visit kept, so they stay and do not drift away.

FinanceIntermediate

Churn

Churn is the share of customers, or of recurring revenue, lost in a period: those who left in a month divided by those at its start. 5% a month is 46% a year.

FinanceIntermediate

LTV

LTV (customer lifetime value) is the gross profit one customer brings over the whole relationship. You compare it with the cost of winning that customer (CAC).

StartupsIntermediate

Product-Market Fit

Product-market fit is when a product satisfies a real market so well that customers stay, come back and bring others without being pushed.

MarketingIntermediate

CAC

CAC (customer acquisition cost) is what you spend on marketing and sales to win one new customer: a period's spend divided by the new customers it brought.

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Quick check

A clinic had 200 clients at the start of the quarter, gained 60 new ones and had 180 active clients at the end. What is its retention rate?

Choose an answer

Frequently asked questions

Do I need to think about retention before I start my business?
Think about the second visit or purchase from the start: what brings a customer back, and when. A business that cannot keep customers has to keep buying new ones.
When does retention first become relevant for a new business?
Once your first group of customers has had time to come back, for a clinic after a few months. Follow that group: if the share still coming stops falling and levels off, a core of customers has found lasting value. One good month says less than that curve.
How do I design my service so customers come back?
Make the next visit easy and natural: offer the next appointment at the end of this one, remind people when it is due, and fix what made them hesitate the first time.
Is retention only for subscriptions and software?
No. A clinic, a salon, a shop or an accountant all have customers who come back or do not. Without logins you count repeat visits or repeat purchases from your own records.
Why does retention matter for a business that is already running?
Because regulars bring revenue without a new advertising cost each time, and some of them recommend you. A small rise in the share who come back adds up month after month.
What goes wrong when a business ignores retention?
It keeps paying to replace customers it quietly loses, and the total number of customers hides the problem until new enquiries slow down.
How do I start measuring retention without stopping daily work?
Take the customers who first came in one month and mark, month by month, how many of them are still coming. A sheet with one row per month is enough for a first cohort.
How can a business owner win back customers during a quiet period?
Call or write personally to regulars who stopped coming, ask what changed and listen. What you hear usually points to the fix, such as a booking problem or a gap in the service.
Can I send offers to customers who stopped coming?
Writing to a customer who stopped coming is one thing. Sending them an offer is another: an offer by email or SMS to a customer who already bought from you is still advertising under section 30A of Israel's Communications (Telecommunications and Broadcasting) Law, 1982. Without their prior consent the law allows it only if they gave their details when buying, were told the details would be used for advertising, were given a way to refuse and did not, and the offer is for a similar product or service. The law does not name any app. It limits the action itself, sending advertising without consent, so the same rule, and the same exception, apply whatever app sends the offer, WhatsApp being one example. Educational material, not legal or tax advice. Check your own case with a lawyer or an accountant.
What does retention mean in plain words?
It is how many of your customers keep coming back. A business with good retention sees familiar faces, one with poor retention sees mostly new ones.
Is measuring retention complicated?
No. You need a start count, an end count and the number of new customers in between, all from your booking diary, invoices or sales list. The formula on this page does the rest.
What is the difference between retention and churn?
They are two sides of one number. Retention is the share of starting customers who stayed, churn the share who left. A retention of 60% for a quarter means a churn of 40%.

Sources: HubSpot, "Customer retention metrics: How to measure and improve retention" (blog.hubspot.com), Communications (Telecommunications and Broadcasting) Law, 1982, section 30A (nevo.co.il)

Last reviewed: 2026-09-24

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