7 Ecommerce Retention Metrics That Actually Matter

Open rate and Klaviyo-attributed revenue can help diagnose an email program, but neither tells you whether retention is making the business structurally stronger.

For established ecommerce brands, the more useful question is whether customers are becoming more valuable, purchasing again faster and improving the economics of acquisition.

The seven metrics in this guide are:

1. 1Contribution margin after marketing
2. 2Blended CAC
3. 330, 60 and 90-day LTV by cohort
4. 4First-to-second purchase rate
5. 5Repeat revenue percentage
6. 6Flow vs campaign attributed revenue
7. 7Time to second purchase

Only one of those is an email reporting number, and that is intentional.

These are business-level retention metrics. They exist to show whether lifecycle marketing is changing customer economics, not whether a single channel dashboard looks impressive this month.

1. Contribution Margin After Marketing

Revenue growth is not healthy growth if the additional revenue produces worse margins.

Contribution margin looks at what is left from revenue once the variable costs of creating that revenue are removed. Depending on how a brand models it, those costs usually include:

• cost of goods sold;
• shipping and fulfillment where relevant;
• payment processing fees;
• marketing spend.

There is no single universal formula here. Different businesses draw the line between variable and fixed costs differently, so the important thing is to define it once and then measure it consistently over time.

The diagnostic moment comes when revenue rises and contribution margin falls. That combination usually points to one of the following:

• discounting doing more of the selling than the message;
• a product mix shifting toward lower-margin items;
• acquisition getting more expensive;
• weak repeat behavior forcing constant new-customer spend;
• retention tactics that buy orders instead of building value.

2. Blended CAC

Blended CAC judges the acquisition economics of the whole business instead of grading Meta or Google in isolation.

It matters for retention because a stronger lifecycle system increases how much acquisition cost the business can economically tolerate. Customers who buy again, buy sooner and buy more create more value after the first order, which changes what a viable CAC looks like.

Retention does not reduce acquisition spend that has already happened. What it changes is the return the business earns on that spend going forward.

Read blended CAC next to:

• payback period;
• contribution margin;
• cohort LTV;
• subscriber-to-customer conversion;
• repeat purchase behavior.

3. 30, 60 and 90-Day LTV by Cohort

Cohort LTV measures how much value a group of customers acquired in the same period creates within a fixed window after their first order.

Take everyone whose first purchase happened in January. Then look at the revenue or contribution that cohort produced in its first 30 days, first 60 days and first 90 days. Do the same for February, March and every cohort after that.

This is far more useful than one blended lifetime value number, because a blended figure mixes mature customers with customers acquired last week and hides the trend you actually need.

If newer cohorts reach higher 30 and 60-day value than older ones, early retention behavior is likely strengthening. Attribute that carefully: product changes, offer changes, traffic quality and lifecycle marketing all move cohort curves.

4. First-to-Second Purchase Rate

First-to-second purchase rate measures what percentage of first-time buyers place another order.

We pay particular attention to it because it is the clearest single signal that a business is converting acquisition into retention rather than renting revenue from paid media.

A realistic target depends heavily on the business. What shapes it includes:

• product type and whether it is consumed or kept;
• replenishment cycle;
• average order value;
• whether a subscription option exists;
• catalog breadth and cross-sell potential.

For that reason we do not publish a universal target. The number that matters is your own trend by cohort.

5. Repeat Revenue Percentage

Repeat revenue percentage shows what share of total revenue comes from returning customers.

It is useful for understanding how dependent the business is on continuous acquisition. A brand where almost all revenue comes from first-time buyers has to keep spending simply to stand still.

Higher is not automatically better. A brand scaling acquisition quickly can see repeat revenue percentage fall while retention behavior is genuinely healthy, because the new-customer base is growing faster than the repeat base can catch up.

Always read it alongside cohort LTV and repeat purchase rate. On its own it can be misleading in both directions.

6. Flow vs Campaign Attributed Revenue

The split between flow and campaign attributed revenue is a diagnostic, not a goal.

Flows create automated lifecycle revenue triggered by customer behavior. Campaigns create ongoing demand, engagement and reasons to buy now. Both are doing different jobs, so more flow revenue is not automatically a sign of a better program.

There is no ideal split, and a 50/50 target is not a benchmark. Healthy mixes vary with:

• length of the buying cycle;
• whether the product replenishes;
• average order value;
• list size and engagement;
• campaign cadence.

A high-AOV brand with a long consideration cycle can look very different from a consumable brand, as we covered in this high-AOV email and SMS case study.

Note also that these are attributed figures. Attribution shows what a platform credits to a channel. It is not the same as the incremental revenue the channel created.

7. Time to Second Purchase

Time to second purchase measures how long it takes a first-time buyer to order again.

Two brands can share the same second-purchase rate and have very different economics if one gets that order in 30 days and the other in 120.

Speed changes:

• cash velocity;
• early LTV inside the 30 and 60-day windows;
• payback period on acquisition;
• when post-purchase and winback messaging should actually run.

This metric is what should set your lifecycle timing. It determines the shape of the post-purchase flow and the trigger point for the winback flow.

How These Metrics Work Together

No single metric answers whether retention is working. The useful signal comes from reading them in pairs.

Low first-to-second purchase rate with weak 30-day LTV

The early retention window is the opportunity. Look at post-purchase experience, product guidance and second-order relevance.

Rising CAC with flat cohort LTV

Retention is not offsetting acquisition pressure. Payback is stretching and the business is becoming more fragile even if revenue grows.

Rising attributed email revenue with declining contribution margin

Investigate discounting and incrementality. The channel may be capturing demand it did not create, at a lower margin.

Long time to second purchase with weak early LTV

Examine the post-purchase journey and the timing of every lifecycle message that follows the first order.

For a fuller view of how these numbers connect to acquisition economics, see retention and ecommerce profitability.

The goal is not to make one dashboard number look impressive.

The goal is to build a system in which customer value improves over time.