Sustainable growth – the 5 most important KPIs in e-commerce

KPIs – Overview with impact

Of course, figures aren’t everyone’s cup of tea. But if you want to hold your own in e-commerce, you shouldn’t ignore your Key Performance Indicators (KPIs). These metrics provide you with measurable insights: where are things going well – and where do you need to make improvements? They’re like a sat-nav for your business. With them, you can optimise processes, identify weaknesses and target your investments more effectively.

Particularly exciting: some KPIs show you with just a few clicks whether your marketing measures are working. And the best thing? Most tools such as Google Analytics, HubSpot or Shopify also provide these figures. The five most important KPIs you should know are

• Acquisition costs (CAC)

• Customer value (CLV)

• Conversion rate (CR)

• Average order value (AOV)

• Return rate (RR)

1. acquisition costs (Customer Acquisition Cost – CAC)

Acquiring customers costs money – that’s no secret. But exactly how much? This is where CAC comes into play. It shows how much you spend on marketing for each new customer you acquire.

The formula is simple:

Marketing costs : Number of new customers = CAC

Online channels in particular offer you the chance to analyse exactly where your customers are coming from – Facebook Ads, Google Ads or perhaps influencer marketing? Not every click leads to a purchase, and not every channel is equally effective. So: measure, compare, optimise.

A Facebook campaign example:

You spend €1000 and gain 125 new buyers. The result? 8 € CAC

This is your key figure. And this is exactly what helps you make smart budget decisions. But be careful: target group and product influence performance. What works for vegan cosmetics may flop for sustainable furniture. The CAC is not a universal solution – it is a tool that you should interpret individually.

Tip: Set up a simple spreadsheet where you can record your monthly CAC per channel. This will help you spot trends – and quickly identify where you can use your budget most effectively.

2. customer value (Customer Lifetime Value – CLV)

Returning customers are worth their weight in gold – especially if they’re truly connected to your brand. The Customer Lifetime Value (CLV) shows you how much revenue a customer generates over the course of their entire relationship with your shop – minus the acquisition costs.

Whilst the CLV isn’t exactly easy to calculate, every approximation helps. It’s particularly important to note that the better your brand is perceived, the more likely customers are to return – rather than switching to the competition. Good design builds trust. Good images stick in the mind.

Formula:

Turnover per customer – CAC = CLV.

If you know the CLV, you can also invest more in the initial approach. Because even if the first purchase is not yet a win – in the long term, the connection pays off. A bit like a good first date with potential.

A common mistake: Many people place ads, expect immediate sales and stop everything if it doesn't work right away. Those who keep an eye on CLV, on the other hand, recognise the long-term effect and can invest more courageously.

Tip: When it comes to customer acquisition, it’s advisable to plan for the long term rather than just looking at the short term. Calculate your CLV on a quarterly basis. This will help you get a feel for how quickly marketing initiatives pay off – rather than having to guess all over again every week.

3. conversion rate (Conversion Rate – CR)

Your shop has 1,000 visitors, but only 16 make a purchase? Welcome to reality – the average conversion rate in e-commerce is 1.6 %, whilst top shops achieve around 3.6 %. The question is: how many of those visitors actually become real customers?

Everything counts here: shop speed, intuitive navigation, trust seal, product presentation and, of course, the visual language. If your products are visually convincing, the probability of purchase increases immediately. UX (user experience) is not a bonus, but a must.

Tools such as Google Analytics or HubSpot show you where users are dropping off. Perhaps the checkout form is too complicated, or the product images are too bland. Or maybe it’s just missing a bit of heart.

Also exciting: Conversion often differs significantly between desktop and mobile. Many shops perform less well on mobile – yet more and more people are buying on the move.

Tip: Take a look at your conversion rate (CR) per device (desktop vs. mobile). Start by improving the mobile user journey – test whether image sizes, text and CTAs work properly on mobile devices. And make sure your key metrics are immediately recognisable.

4. average shopping basket value (Average Order Value – AOV)

The higher the AOV, the better for your sales.

Quite simply:

Total sales : number of orders = AOV.

Example:

If your shop generates €100,000 in sales with 500 orders, the average shopping basket is €200.

But how do you increase this figure? Two strategies: upselling and cross-selling. Recommend suitable products or higher-value alternatives – but do so subtly and stylishly. A visually well-presented bundle is more persuasive than a clumsy "Why not buy this as well?" message.

Well-designed product pages also help. Beautiful photos, comprehensible texts and a clearly structured presentation not only increase trust – they also invite you to browse. This often leads to more items in the shopping basket without being intrusive.

Your design therefore plays a key role in determining how „valuable“ your shop appears. Customers are more likely to buy three products if they feel emotionally engaged – and visual storytelling is your best friend here.

Tip: Try adding a prompt at checkout: “You’ve got the lip balm – why not try it with our organic hand cream too?”. A small addition with a big impact on average order value – without coming across as pushy.

5. return rate (Return Rate – RR)

Now things are getting tricky. The online returns rate in Germany stands at 4 %, and for fashion it’s as high as 28.5–70 %. That’s hardly surprising, as there are additional reasons here, such as the product being different from expected (approx. 50 %), the product being damaged (approx. 25 %), an alternative having been ordered (approx. 20 %) or even impulse purchases (5 %). Particularly critical: amongst the 14–29 age group, an above-average number return items – often because the product doesn’t fit or doesn’t meet expectations.

What is often forgotten: Every return is not only a cost factor, but also an environmental problem. Packaging, transport, storage – all consume resources. If you want to sell more sustainably, you have to take countermeasures here.

There are many reasons for returns: unclear sizes, bad photos, damaged products or simply impulse purchases. The solution? Honest, high-quality product presentation, good packaging, clear information. Say how the shoe really turns out – and show how it looks when worn.

Psychological tricks also help: Returns are more frequent with purchase on account than with prepayment. Small incentives such as discounts or give-aways can help to minimise returns – without preventing the purchase.

Tip: Collect specific reasons for returns (e.g. via stickers attached to items or return forms). This will help you prioritise your actions – and achieve more with fewer returns.

KPIs are more than just numbers

At first glance, key figures seem sober, but they are extremely valuable. They show you where you are losing money, where you should invest wisely and how you can become more successful in the long term. Instead of just acting on instinct, KPIs give you a solid foundation for strategic decisions.

Be careful not to optimise all KPIs at the same time. Set priorities, try things out, compare channels and keep an eye on long-term developments. Remember: success in e-commerce is not a sprint, but a sustainable marathon – and KPIs are your compass.

You don't just want to optimise KPIs, you want to make your brand really shine?

Then start with what really excites your target audience: product photos that build trust, a corporate identity that creates brand recognition, and giveaways that build customer loyalty, even before the shopping basket is filled.

Here at 2bu design, we’ll help you to visual clarity, find your style and build a brand identity that doesn’t rely on loud marketing – yet still makes an impact. Fewer returns thanks to better product presentation, more sales through emotional imagery, and a design strategy that aligns with your values.

Sounds good? Then let’s work together to see how we can position your brand in a way that will make your KPIs happy too – sustainably, efficiently and with substance.