The #1 eComm Metric You’re Probably Ignoring

Let’s talk about a metric that most eComm brands overlook—but the ones who track it? They scale smarter and more profitably.

I’m talking about returning customers.

Here’s the deal: If you’re not actively tracking who’s coming back to buy from you, you’re flying blind. You need to understand customer behavior over time—because that’s where the real profit is.

The big mistake I see brands make is looking at their PERCENTAGE of new customers and thinking that tells the whole story. If 50% of your customers last month were returning, that doesn’t mean half of all your customers are coming back.

What we really want to know is:

• What was the absolute number of returning monthly customers and is that number growing over time?
• How many returning customers can we rely on each month?
• On the flip side - how many new customers do we need to get in order to grow?
• How much can we afford to pay to acquire that customer, assuming they come back at a similar rate?

Why does this matter?

Retention is cheaper than acquisition. If your customers come back and buy again, you can grow much faster than a brand that is constantly spending all their marketing budget on acquiring new people.

It helps you forecast revenue. Looking at your repeat purchase rate over time (a cohort report in Shopify is perfect for this) lets you see exactly how many new customers you’ll need to hit your goals.

It tells you if your ads are actually profitable. If your cost of acquiring a customer is $50, and your AOV is $100, that is okay if you know customers come back quickly and often. But if they aren’t coming back you are in a race to bankrupt-town.

Now, let’s get practical—here’s how to do it:

1) Track how many returning customers you get every month.

I am not talking about the percentage, but the actual number of purchases and revenue that has come from your returning customers. ?

?? Shopify Admin > Analytics > Reports

Go to Shopify Admin

Click Analytics > Reports

Under Customers, select First-time vs. Returning Customer Sales.

Select ‘last month’ to see this for last month

?? In the same "First-time vs. Returning Customer Sales" report:

Scroll down to see the total revenue breakdown

Look at the revenue share from Returning Customers

This is the number you need to start tracking to make sure you are consistently growing your returning customers each month.

If this number is not going up then you may have a problem with your product that needs fixing or need to address retention channels like email marketing.

2) Check Shopify’s cohort report—see how quickly and often new customers come back.

The Shopify cohort analysis helps you track how many customers return over time. Here’s how to find it:

Go to Shopify Admin > Click on Reports

Scroll down to Cohort Analysis

Set the date range (e.g., last 6 or 12 months)

Look at the percentage of customers returning each month after their first purchase

What to look for:

• Are customers coming back within 30, 60, 90 days?
• What’s the drop-off rate after the first purchase?
• Do repeat buyers spend more than new customers?

Why this matters: If your repeat purchase rate is low, you likely have an issue with product-market fit, post-purchase experience, or retention marketing.

From this report alone you can get an idea of the lifetime value of your customers.

What do I do with this information though?

So now you know how often people are returning to you, and have a solid idea of how much of your revenue is coming from that loyal returning customer base.

The next step is to look at what it costs you to acquire a new customer and work out if it is low enough for you to grow profitably in the long term.

How to Calculate your nCAC (new Customer Acquisition Cost).

This is the true cost to acquire a new customer—not just your blended CAC.

Formula:

nCAC = Total Ad Spend on New Customers / # of New Customers Acquired

?? In Shopify:

Go to Analytics > Customer Reports

Look at First-Time Customers for the period you're analyzing

?? In Meta & Google Ads:

Pull the total amount you spent on ads for that period. You are not looking at the budget spent just on new customer acquisition - because there is not an easy way for Meta or Google to separate this, you are going to have to assume that all your budget is going towards new customers.

Now simply divide what you spent on ads by the number of new customers you had in that period.

This is your nCAC!

What to look for:

• If your nCAC is too high, you may be overpaying for new customers
• If nCAC is higher than your AOV, you’re losing money upfront
• Your nCAC should be lower than your LTV—otherwise, your ads aren’t sustainable

The Bottom Line

The best brands know their numbers. If you’re tracking cohorts, new and returning customers, and nCAC, you’ll scale with confidence instead of guessing.

?? Your challenge:

Go check your cohort report today and reply—what’s your average return rate after 90 days? Does this align well with how much it is costing you to acquire that customer (your nCAC)?

x

Jessie

ps. If numbers are not your strong point and you want me to take a look and help explain it in person - book a free call - here is a link to my Calendly where you can book a call at a time that works: https://calendly.com/jessiehealy/coffee_with_jessie