The E-commerce Metrics & KPIs That Actually Matter

Most e-commerce dashboards are noise. Sessions, likes, add-to-carts, a headline ROAS figure – plenty of numbers, very little signal. The metrics that really matter are the handful that tell you whether you can profitably acquire a customer and keep them. Below are the ten KPIs we track for every store we run, each with its formula, a benchmark to judge yourself against, and why it earns its place.

The ecommerce KPIs at a glance

Metric	Formula	What good looks like (2025 benchmark)	Why it matters
Qualified visitors	Sessions from your target audience	No fixed target – judge by whether CVR holds as traffic grows	Volume is worthless if the intent is wrong
Conversion rate (CVR)	Orders ÷ sessions × 100	~1.5–3.5% (UK average ≈ 3.4%)	Turns existing traffic into revenue
Average order value (AOV)	Revenue ÷ orders	No universal figure – split new vs returning; returning should be higher	Fastest lever for revenue without more spend
Purchase frequency	Total orders ÷ unique customers	Repeat-purchase rate ~20–30% (higher for consumables)	Retention multiplies lifetime value
Cart abandonment rate	(Carts created − completed) ÷ carts created	~70% average; under 65% is strong	Exposes checkout friction leaking revenue
Media efficiency ratio (MER)	Total revenue ÷ total ad spend	Directional – often 3–4x+ to be profitable, margin-dependent	Blended view that ROAS hides
New customer CAC (NCAC)	New-customer spend ÷ new customers	Below first-order gross profit	Guards profitability on the first sale
Gross margin	(Revenue − COGS) ÷ revenue × 100	DTC often targets 60–70%+ (directional)	The cash that funds everything else
Customer acquisition cost (CAC)	Total marketing spend ÷ all new customers	Below LTV; feeds the ratio below	The all-in price of a customer
LTV : CAC ratio	LTV ÷ CAC	3:1 healthy (2:1–4:1 range)	The single best test of scalable economics

Treat the benchmark column as a directional rule of thumb, not gospel – every category, price point and margin profile is different. The point is to know roughly where healthy sits, then beat your own numbers month on month.

The ten metrics that really matter

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.

Formula: CVR = orders ÷ sessions × 100.

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.

Benchmark: UK stores average around 3.4%, with most sitting in a 1.5–3.5% band. Beauty and skincare often see 3–4%, luxury closer to 1%. Judge yourself by category, not the headline average.

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.

Formula: AOV = revenue ÷ number of orders. Run it twice – once for new customers, once for returning.

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.

Formula: Purchase frequency = total orders ÷ unique customers (over a fixed window). The share of customers who buy more than once is your repeat-purchase rate.

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.

Benchmark: A repeat-purchase rate of roughly 20–30% is typical, and higher for consumables and replenishable products. Anything you can do to lift it flows straight into LTV (metric 10).

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.

Formula: Cart abandonment rate = (carts created − completed purchases) ÷ carts created × 100.

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

Benchmark: The Baymard Institute puts the average across studies at around 70%. If you’re under 65% you’re doing well; mobile almost always abandons more heavily than desktop, so segment by device.

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.

Formula: MER = total revenue ÷ 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.

A note on POAS and contribution margin: MER still measures revenue, not profit. The real north star is Profit on Ad Spend (POAS) – or contribution margin after ad spend – which strips out COGS, shipping and fees before it judges a campaign. Two accounts with an identical MER can have wildly different profitability once margin is in the picture. We cover this in more depth in why ROAS is misleading and what you should track instead.

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.

Formula: NCAC = new-customer acquisition spend ÷ number of new customers.

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.

Benchmark: There’s no universal figure – a healthy NCAC is simply one that sits below the gross profit on the first order (and comfortably below full LTV). If you want to go deeper on this, read stop obsessing over CAC in DTC.

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.

Formula: Gross margin = (revenue − COGS) ÷ revenue × 100.

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.

Benchmark: Many healthy DTC brands aim for 60–70%+ gross margin so there’s enough headroom to fund acquisition, but this is highly category-dependent – electronics run thin, cosmetics run fat.

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.

Formula: CAC = total marketing spend ÷ all new customers acquired.

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. For the full picture of how CAC connects to payback and repeat behaviour, see CAC payback period vs repurchase rate.

10. Customer Lifetime Value and the LTV : CAC Ratio

Every metric above feeds into this one. Lifetime value (LTV, sometimes CLV) is what a customer is worth to you across their whole relationship, not just their first order – and it’s only meaningful when you weigh it against what it cost to acquire them.

Formula: LTV = AOV × purchase frequency × gross margin %. The relationship that matters is the ratio: LTV ÷ CAC.

Example: If your AOV is £60, customers buy three times, and your gross margin is 60%, your LTV is £60 × 3 × 0.60 = £108. If your CAC is £36, your LTV : CAC ratio is 3:1.

Benchmark: A 3:1 ratio is the widely-cited healthy target, with most brands living somewhere in a 2:1 to 4:1 range. Below ~2:1 and you’re acquiring too expensively or retaining too weakly; much above 4:1 and you’re probably under-investing in growth and could afford to spend more to acquire. Measure LTV on margin (contribution), not revenue, or the ratio flatters you. For a full treatment, see mastering unit economics in paid ads.

What to do: Push both sides. Lift LTV with retention, higher returning-customer AOV and frequency; hold CAC down with sharper targeting and creative. The ratio is the truest test of whether you can scale profitably.

Making 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 ten. Master them, measure them properly, and build your growth engine from the inside out.

FAQ

What is the single most important ecommerce KPI?

If you can only watch one, watch the LTV : CAC ratio. It rolls up conversion, AOV, frequency, margin and acquisition cost into a single test of whether your economics can scale. A ratio around 3:1 is the widely-used healthy benchmark.

What is a good conversion rate for an ecommerce store?

UK stores average roughly 3.4%, and most sit in a 1.5–3.5% band. But it’s highly category-dependent – beauty often converts at 3–4% while luxury may sit near 1% – so benchmark against your sector and, more importantly, against your own trend.

How do you calculate customer lifetime value (LTV)?

A simple, robust version is LTV = average order value × purchase frequency × gross margin %. Using gross margin (rather than revenue) keeps it honest, because it reflects the actual profit a customer generates rather than top-line sales.

Why use MER instead of ROAS?

ROAS is usually channel-specific and last-click, so it double-counts and flatters. MER (total revenue ÷ total ad spend) gives you a blended, account-wide view. Better still, move to POAS or contribution margin so profit – not just revenue – drives your decisions.

What is a normal cart abandonment rate?

Around 70% is the long-run average across studies from the Baymard Institute, and it has barely moved in a decade. Under 65% is strong. Mobile almost always abandons more than desktop, so always segment by device before you panic.