How to calculate the cost of customer retention
Most CRC guides come from SaaS and divide by active subscribers. An online store has no subscription to renew, so the useful denominator is the number of customers who placed another order in the period:
| Cost line | What goes in | Often forgotten |
|---|---|---|
| Tools | Email platform, WhatsApp Business Platform fees, loyalty and review apps | Message fees per template |
| People | In-house retention team, agency, freelance design and copy | Share of a founder's time |
| Discounts | Codes and automatic discounts redeemed on repeat orders | Codes used by customers who would have bought anyway |
| Rewards | Points, gifts and free shipping redeemed by existing customers | Free samples in reorder packages |
| Paid reach | Ad spend aimed at past buyers | Retargeting that mostly reaches recent customers |
Discounts are the line most stores leave out. Every 15% code on a repeat order is margin you gave away, so it belongs in the cost of retention the same way a tool subscription does.
Worked example: CRC for an ecommerce store
A store won 30,000 customers over the last 12 months. In one quarter, 8% of them ordered again, which gives 2,400 retained customers at an average order value of $85. That is $204,000 in repeat revenue. Before any retention work, the same store saw a 5% reorder rate, or 1,500 customers.
| Retention cost in the quarter | Amount |
|---|---|
| Email and WhatsApp tools | $6,000 |
| Team and agency | $24,000 |
| Discounts: 960 repeat orders × $85 × 15% | $12,240 |
| Loyalty rewards redeemed | $3,000 |
| Ad spend aimed at past buyers | $4,760 |
| Total retention cost | $50,000 |
| View | Calculation | Result |
|---|---|---|
| Blended CRC | $50,000 ÷ 2,400 retained customers | $20.83 |
| Retention cost share | $50,000 ÷ $204,000 repeat revenue | 24.5% |
| Incremental CRC | $50,000 ÷ 900 extra reorders (2,400 − 1,500) | $55.56 |
| CAC for comparison | $150,000 ad spend ÷ 3,000 new customers | $50.00 |
The blended CRC of $20.83 looks like retention costs less than half of acquisition. Count only the 900 customers the program added, and each one cost $55.56, more than a new customer at $50. The $12,240 in blanket discounts went mostly to buyers who would have reordered anyway.
Replace the blanket code with a targeted $3,000 offer for lapsing customers. At the same 900 extra reorders, incremental CRC falls to $45.29. The fix sits in the discount line. Cutting the tool bill would barely move it.
Customer retention cost vs. acquisition cost
The most quoted comparison comes from Frederick Reichheld of Bain & Company. As Harvard Business Review summarized in 2014, acquiring a new customer costs five to 25 times more than retaining an existing one, and a 5% rise in retention lifts profits by 25% to 95%.
Those ranges are wide because they depend on how you count. Compared on blended CRC, retention nearly always wins. Compared on incremental CRC, as in the example above, it can lose. Use the incremental number when you decide how much budget retention gets.
The two numbers belong in one equation. Your LTV calculation tells you how much contribution margin a customer brings over their lifetime. That number caps what you can spend on acquisition and retention combined.
Where retention spend goes, and what we run
Retention is one of four levers in our 90-day sprint, next to waste, budget allocation and conversion. All four run without extra budget, and retention is the one that needs no ad spend at all. Julian, our Head of Retention, owns email, WhatsApp, repeat purchases and customer lifetime value.
Email flows and campaigns
Welcome, abandoned checkout, post-purchase, replenishment and winback, plus segmented campaigns. How we work as one of the email marketing firms in this space has its own page.
Klaviyo setup
Data sync, segments and flows inside your account. What we build there is on our Klaviyo agency page.
Order and shipping updates and service replies for customers who opted in, plus campaigns outside the US. Details under marketing in WhatsApp.
Discount policy
Targeted offers for lapsing customers in place of blanket codes, so the discount line in your CRC shrinks.
Winback
Customers past their usual reorder window get their own sequence, timed to your real purchase cycle.
Holdout groups
A small random group gets no message, so you see which reorders the program added.
Who retention marketing pays off for
- Your products get reordered or topped up: supplements, skincare, pet supplies, food, apparel basics.
- Your CAC keeps rising, and new customers only become profitable on their second order.
- You have several thousand past buyers but little automated post-purchase messaging.
- You want to grow revenue without raising ad spend.
Retention does not replace acquisition. Without new customers the base shrinks. We plan both together: Google Ads wins customers at a target that the later reorder can carry, and retention collects that value.
How we work with you
- 01
Intro call
30 minutes with Tobias, our co-founder. We look at your customer base, reorder rate and what you spend on retention today.
- 02
Analysis
On day 0 we lock in the baseline. We calculate blended and incremental CRC and find the cost lines that buy the least.
- 03
Implementation
From day 15 to 45 we rebuild flows, segments and offers ourselves, with holdout groups on the main flows. Your team approves.
- 04
Measurement in your shop backend
A status update every week and a detailed review on day 30, always with revenue from your shop, minus returns.
Results and guarantee
At Solys the share of revenue from retention grew from 12% to 35%, and the brand went from seven to eight figures before its exit. Across all brands we have managed $720M in revenue. How we measure extra revenue for the guarantee is in the conditions.
Seven figures to eight figures.
Retention share 12 → 35%, then exit
+30% revenue in 3 months.
Acquisition cost −35%
$100,000 to around $600,000 monthly revenue.
Acquisition cost $220 → $100
+$100,000 revenue in 90 days at the same ad spend.
No +$100,000 on day 90? All three monthly retainers back. Measured in your shop backend, not the ad account.
The guarantee starts at $3M annual revenue. You can still book a call below that. See the conditions
Harucon works as a growth partner. The guarantee starts at $3M annual revenue, and you can book a call below that.
How to spot a good retention marketing agency
- It calculates your CRC before it starts. You see blended and incremental numbers, with your own costs and customer counts.
- It counts discounts as cost. An agency that reports revenue from coupon flows without the margin behind them hides the biggest line.
- It tests with holdouts. Without a control group, nobody knows which reorders the program caused.
- It measures in your shop. Revenue your email tool attributes to itself includes orders that would have happened anyway.
Cost of customer retention: FAQ
What is the cost of customer retention?
It is the total you spend to get existing customers to buy again in a period, divided by the number of customers who reordered in that period. In ecommerce it covers tools, people, discounts, rewards and ad spend aimed at past buyers.
How do you calculate customer retention cost?
Add up all retention costs for a period, including discounts redeemed on repeat orders, and divide by the customers who placed another order in the same period. $50,000 in costs and 2,400 reordering customers give a CRC of $20.83.
Is retaining customers cheaper than acquiring them?
On a blended basis, usually yes. Harvard Business Review cites Bain research putting acquisition at five to 25 times the cost of retention. Counting only the reorders a program adds, the gap can shrink or flip, so check your incremental CRC.
What is a good customer retention cost?
One that stays below the contribution margin a retained customer brings. Compare your incremental CRC with your CAC and with the margin of the reorders you win.
How can I lower my cost of customer retention?
Swap blanket discount codes for targeted offers, suppress contacts who never engage, and time flows to your real reorder cycle. Holdout groups show which spend adds reorders.
What does retention marketing cost at Harucon?
That depends on the size and starting point of your brand. After the intro call you get a fixed offer in writing, before anything starts.
What does retention really cost you?
On the intro call Tobias works out your blended and incremental CRC with the numbers from your shop. 5 quick questions, then straight to the calendar.
Book your free intro call→