The cost of running an eCommerce business has risen significantly. Paid media is more expensive, fulfilment costs are rising, and return rates continue to climb. On top of that, platform and app fees quietly add up over time.

Brands that relied on cheap acquisition and high revenue are starting to feel the pressure. Those that continue to scale are focusing less on how much they sell and more on how profitable those sales actually are.

If you’re still measuring success primarily by revenue, you’re working with an incomplete picture.

The Metrics That Actually Matter

There are three numbers that every mid-market eCommerce brand should track consistently:

Gross Margin

Gross margin is the first indicator of your commercial health. It’s what remains after the cost of goods sold. If it’s shrinking, no volume of traffic or paid spend will fix it. A brand running at 30% gross margin has very little room to absorb rising acquisition or fulfilment costs. A brand running at 65% has options.

Contribution Margin

Contribution margin goes deeper. It’s what remains after all variable costs are removed: paid media, fulfilment, returns, packaging and transaction fees. This is the number that tells you whether a channel, product line, or campaign is actually worth running.

Many brands discover, when they calculate this properly for the first time, that some of their most active channels are losing money per order. That isn’t a paid media problem – it’s a profitability visibility problem.

Marketing Efficiency Ratio (MER)

The marketing efficiency ratio (MER) is total revenue divided by total marketing spend. It helps you understand overall performance beyond return on ad spend (ROAS), especially as you scale across multiple channels.

As you scale across paid search, paid social and other channels, MER becomes a more reliable indicator of whether your marketing investment is working as a whole.

Don’t Let Your Brand Lose Visibility

Returns are underreported

A brand showing £500k in monthly revenue could be handling £80k in returns that aren’t properly reflected in reporting. The headline number looks healthy, but the actual position is different. Until returns are accurately tracked, your revenue figure is telling you less than you think.

Blended acquisition costs hide inefficiency

If paid social is generating customers at a loss while organic and email are performing well, a blended average can mask the problem. It’s imperative to analyse each channel respectively so that you know where to invest and where to pull back. When everything is averaged out, it’s easy to miss the issue. 

Lifetime value is often measured too soon

Brands that report lifetime value (LTV) at 30 or 60 days are working with incomplete data. A reliable LTV model runs for a minimum of 12 months and segments by acquisition channel, product category, and cohort. Without looking at performance over time or by channel, it’s difficult to make accurate decisions around retention and growth.

What ‘Good’ Looks Like in Practice

The brands that manage profitability well tend to share a few characteristics. They track contribution margin by channel, not just across the overall business. They know which campaigns, product lines, and customer segments are profitable, and they make resourcing decisions accordingly.

High return rates should be treated as a product or user experience problem, not just a fulfilment cost. Improving product descriptions, sizing guides, imagery, and the on-site experience can materially reduce returns without touching the logistics operation.

Successful businesses also separate vanity metrics from operational metrics. Monthly active users, social followers and email open rates have their place. But they don’t drive commercial decisions. Revenue per session, conversion rate by traffic source, contribution margin by channel and repeat purchase rate do.

Before increasing a paid media budget, leading brands stress-test the contribution margin across different acquisition costs. If the margin does not hold at scale, the spend does not increase.

A Practical Starting Point

Start with a simple check across your main channels. Look at the revenue each one generates, factor in the costs, and understand which channels are actually contributing to profit, not just driving volume.

This will tell you where to focus, where to pull back and where the real growth opportunity sits.

Understanding the difference between revenue and profitability isn’t just a finance task. It’s the key to scaling your business. 

Where Velstar Can Help 

If you would like an overview of how your paid activity is performing and where margin may be lost, our team of experts are happy to take a look. Get in touch by completing our short contact form.