The Only 9 Metrics That Really Matter in eCommerce

Let’s cut through the fluff. eCommerce is full of noise – new tools, shiny dashboards, endless advice. But if you’re running a store, there are only nine numbers you need to worry about.

I’ve scaled, fixed, and fuelled dozens of eCommerce brands, and I can tell you this: focus on these nine metrics, get them working together (not in isolation), and you’ll move from treading water to full sprint.

Let’s dive into them – with context, real-world examples, and what to do next.

1. Number of Visitors

This is your traffic. It’s the footfall of your store. More eyeballs usually means more chances to convert – but only if you’re bringing in the right kind of visitors.

Example: Let’s say you’re running a premium skincare brand. You get 20,000 visitors a month, but only 1% convert. If that traffic’s coming from broad, non-branded search terms, or your TikTok videos are going viral with teens who can’t afford your products, then those visitors won’t move the needle.

What to do: Traffic should be qualified. Use paid media strategically – Google Shopping, Meta retargeting, influencer partnerships – but always monitor what kind of audience is landing. Focus on intent, not just volume.

2. Conversion Rate (CVR)

This is the percentage of visitors who actually buy. It’s your ability to turn interest into revenue.

Example: If your conversion rate is 2% and you bring in 10,000 visitors, that’s 200 sales. But if you lift that to 3%, you’re at 300 sales – without increasing traffic. That’s a 50% increase in revenue.

What to do: Focus on landing page clarity, product photography, trust signals (reviews, delivery timelines), and mobile UX. Small changes make a big difference. Run A/B tests, not hunches.

3. Average Order Value (AOV)

AOV is one of the fastest levers for driving more revenue without increasing traffic or spend. But here’s the mistake I see far too often: brands only look at blended AOV. That’s like trying to manage your finances using just your bank balance – you’re not seeing what’s coming in or going out.

To do it properly, you need to break it down into two separate numbers:

• New Customer AOV
• Returning Customer AOV

Why? Because they behave differently – and they should be treated differently.

Example: Let’s say your overall AOV is £60. That looks decent on paper. But when you dig deeper, you find:

• New customer AOV: £42
• Returning customer AOV: £78

Suddenly, it’s clear where the opportunity is. That new customer AOV is dragging the average down – and worse, if your CAC is anywhere near £40, your margin on that first sale is getting squeezed.

What to do:

• For new customers: Focus on increasing AOV through smart entry-level bundles, first-order upsells, and minimum spend incentives. You want to front-load value while staying relevant – don’t offer three-pack bundles to someone still unsure if they’ll like your product.
• For returning customers: This is where you can really move the needle. Use personalised product recommendations, loyalty tiers, and product launches to encourage larger baskets. These customers already trust you – they just need the right nudge.

By understanding which customers are spending more and why, you can optimise campaigns, landing pages, and offers that are tailored to different behaviours – rather than guessing based on a blended number that hides the truth.

In short: don’t just chase a higher AOV. Chase a smarter one.

4. Purchase Frequency

How often do your customers come back? If you’re not paying attention to this, you’re leaving money on the table.

Example: If a customer buys once a year, and their AOV is £50, they’re worth £50. But if they come back three times, that’s £150. That’s 3x more lifetime value with no extra acquisition cost.

What to do: Email flows, loyalty programmes, replenishment reminders – these aren’t just nice to have. They’re revenue multipliers. Retention isn’t glamorous, but it’s where the profit lives.

5. Cart Abandonment Rate

This is the silent killer. If people are adding products and bailing before checkout, you’re leaking revenue.

Example: If 1,000 people add to cart, but only 400 complete purchase, your abandonment rate is 60%. That’s 600 missed sales.

What to do: Fix checkout friction. Simplify steps, reduce form fields, offer multiple payment options (Apple Pay, Klarna, PayPal), and follow up with abandoned cart emails or SMS within 30 minutes. Urgency works.

6. Media Efficiency Ratio (MER)

Think of MER as the grown-up version of ROAS. It’s total revenue divided by total ad spend.

Example: You spend £10,000 on ads and generate £50,000 in sales. Your MER is 5.0. But here’s the kicker – you need to look at blended MER, not just channel-specific numbers. Facebook may say 8.0, but your overall account could be at 2.5 once you factor in attribution and brand traffic.

What to do: Track total performance, not just channel performance. Brands that obsess over last-click ROAS often strangle their growth. Look wider.

7. New Customer Acquisition Cost (NCAC)

This is how much it costs you to bring in a fresh customer. You can’t scale if you’re paying £60 to acquire someone worth £40.

Example: If your NCAC is £25 and your first-purchase AOV is £50, you’re in good shape. But if your AOV drops to £20 and you’re still spending £25 to acquire, you’re upside-down.

What to do: Get creative with top-of-funnel. Run efficient Meta and TikTok ads, but also explore partnerships, organic influencer seeding, and email lead magnets to reduce CAC over time.

8. Gross Margin

Revenue is vanity. Margin is reality. If your gross margin’s too slim, you’ll struggle to reinvest in growth.

Example: If your product sells for £100 but costs £70 to make and ship, your gross margin is 30%. That leaves £30 to cover marketing, operations, and profit. It’s tight.

What to do: Review your COGS quarterly. Look at packaging, freight, fulfilment fees, and even discounting strategies. Many brands kill their margin through lazy promotions and blanket codes. Be strategic.

9. CAC (Customer Acquisition Cost)

Different to NCAC, this is your overall cost to acquire a customer across all channels and touchpoints.

Example: Let’s say you spend £50,000 in marketing over a month and bring in 1,000 new customers. Your CAC is £50. To be profitable, your average customer needs to generate at least that – ideally more.

What to do: Work backwards from margin. If your gross profit per customer is £70, then a £50 CAC leaves you £20. That’s not bad, but you need volume and retention to make it work.

Concluding: Make These Numbers Dance Together

The magic happens when you stop treating these metrics in isolation. Improving CVR without fixing AOV is fine, but fixing both at once? That’s scaling fuel. Same goes for CAC and frequency – the more your customers come back, the more you can afford to pay to get them in the door.

This is what we do every day at HOC-Digital – break down the numbers, find the gaps, and create ad strategies that don’t just drive clicks, but drive profitable growth.

If you’re stuck in the weeds and want clarity, start with these nine. Master them, measure them properly, and build your growth engine from the inside out.