Rising cost per acquisition is the most commonly misdiagnosed constraint in ecommerce. It is usually a symptom of what happens after the first order.
Each figure is a measured band against the pre-engagement baseline stated beside it. Ranges are used because the underlying numbers are real and anonymised, not rounded into a single headline claim.
Second-order rate
+21% to +28%
Baseline: Baseline 18% of first-time buyers reordering within 12 months
Two quarters post-engagement
Contribution margin per customer
+11% to +15%
Baseline: Baseline margin after delivery and returns
Two quarters post-engagement
Lifecycle discount load
−32% to −40%
Baseline: Baseline share of repeat revenue placed on a discount code
One quarter post-engagement
Planned media increase avoided
£240k–£300k
Baseline: Committed annual budget uplift into a new paid channel
Stopped at diagnostic sign-off
Presented as
"Our CAC has risen every quarter for two years. We need cheaper acquisition or a new channel."
The real constraint
First-order acquisition efficiency was in line with category expectations. Second-order rate was materially below what the basket value and replenishment cycle should support, so every pound of media was being asked to fund growth on its own.
Reporting was organised by channel, and every channel report showed the same upward cost curve. Nobody was reporting on the economics of a customer beyond the first order, so the only visible number was getting worse and the only visible lever was media.
Cohort behaviour by acquisition source and first product category, contribution margin after delivery and returns, the post-purchase and lifecycle programme, and the discovery position for high-intent category demand. The commercial model was rebuilt so a customer, not a session, was the unit of analysis.
Two acquisition sources with the highest apparent cost produced the highest-value repeat cohorts, and were being throttled on first-order ROAS. The lifecycle programme was effectively a discount calendar, training exactly the behaviour that was compressing margin. Category discovery for the highest-margin range was weak relative to comparable retailers.
Investment was reallocated toward the cohorts that repeated rather than the ones that looked cheapest on day one, the lifecycle programme was rebuilt around replenishment and range discovery instead of blanket discounting, and a target was set on second-order rate as a board-level metric alongside CAC.
The Growth Economics Snapshot takes a few minutes and shows where your biggest commercial lever sits before you commit to anything.