Repeat sales (retention): how to measure customer retention
Repeat sales show what share of customers and revenue comes from repeat purchases after the first transaction. It is an indicator of loyalty and the “health” of the customer base: high retention reduces dependence on costly acquisition, increases LTV, and makes revenue more predictable.
Why the Metric Matters
Retention shows how well the value of a product/service is confirmed by customer behavior. It helps you understand which categories “hold on to” customers, how service and delivery perform, whether acquisition channels are burning out, and where it is worth investing in a loyalty program.
Calculation
- Share of repeat customers, % = No. of customers with ≥2 orders / No. of customers with ≥1 order
- Share of revenue from repeat customers, % = Revenue from repeat customers / Total revenue
- Purchase frequency = No. of orders / No. of unique customers
- Average interval between purchases — the median or mean time between the first and subsequent purchases
- Cohort retention: for a “month of first purchase” cohort, calculate the share of customers who made a repeat purchase in M+1, M+2, M+3…
Standardize the rules: exclusion of test/internal orders, accounting for returns, customer deduplication.
Calculation example
500 customers bought in January, and 180 of them made another purchase within the next three months. Three-month retention = 180 / 500 × 100 = 36%. A 55% share of repeat purchases in March revenue shows how much the business relies on returning customers.
Data Sources
CRM and billing, online store CMS and marketplaces, payment providers, analytics (customer identification by e-mail/phone/ID). It is important to have a single customer master list and a canonical method for merging profiles.
Interpretation
Growing retention with a stable CAC means a better product/service or relevant post-purchase offers. A decline signals problems with quality, availability, delivery, or communications. Evaluate not only the overall percentage but also the time to second purchase: the shorter it is within your consumption cycle, the faster acquisition pays off.
Useful Breakdowns
- Acquisition channels and campaigns
- Categories/SKUs and first-purchase baskets
- New vs repeat customers, loyalty programs
- Regions, points of sale, managers
- Trigger types: e-mail / SMS / push, personalized offers
Dashboard Visualizations
- Cohort heat maps (retention M+1/M+2/M+3…)
- Repeat purchase curves over time (retention curves)
- Trend of the share of revenue from repeat customers
- Distribution of intervals between purchases
- RFM segmentation (Recency–Frequency–Monetary)
Approaches to Growth
- Personalized recommendations after the first purchase (complementary products/services)
- Lifecycle triggers: reminders, replenishment, service updates
- Bundles/subscriptions, bonus programs, cashback, and loyalty tiers
- Improving the “after-sales” experience: delivery, returns, support
- Content and community around the product: guides, case studies, use cases
How to Set Targets
Start from the consumption cycle in your category: set targets for M+1 / M+3 / M+6, for time to second purchase, and for share of revenue from repeat customers. For new channels, set lower initial benchmarks and review them monthly.
Common Mistakes
- Mixing cohorts (new with old) and double counting customers
- Ignoring returns in calculations
- Counting one-time promotions as “sustainable” retention
- No single customer ID
- Comparing unequal periods or seasons
Questions for Discussion
- What do customers most often buy a second time, and why?
- Which acquisition channel delivers the best long-term retention?
- What interval to the second purchase is normal for our category?
- Which triggers and offers deliver the largest uplift in repeat purchases?