KPI stands for Key Performance Indicator. It is a metric directly linked to a business objective that lets you evaluate whether you are moving in the right direction.
The keyword is key. Not all metrics are KPIs. You can measure hundreds of data points across your digital channels, but only a few are truly key indicators. The number of visits to your website is a metric. The conversion rate of those visits into customers is a KPI, because it is directly connected to revenue.
A metric is any quantifiable data point: page views, social media followers, emails sent. A KPI is a metric that meets three conditions:
The number of Instagram followers is a metric. The percentage of followers who visit your website and buy is a KPI. The difference is not in the data itself, but in how you use it to make decisions.
We have organised the indicators into four categories that reflect the stages of the customer lifecycle: acquisition, conversion, retention and revenue. This structure lets you quickly identify in which phase you have improvement opportunities.
| Category | KPI | What it measures | Formula / How it is calculated |
|---|---|---|---|
| Acquisition | 1. Cost Per Acquisition (CPA) | How much it costs to get a new customer | Total investment / New customers |
| Acquisition | 2. Cost Per Lead (CPL) | How much it costs to generate a lead | Acquisition investment / Leads generated |
| Acquisition | 3. Organic traffic | Visits from unpaid searches | Sessions with source/medium = organic |
| Acquisition | 4. CTR (Click-Through Rate) | Percentage of clicks over impressions | (Clicks / Impressions) x 100 |
| Conversion | 5. Conversion rate | Percentage of visitors who convert | (Conversions / Visitors) x 100 |
| Conversion | 6. Conversion rate by channel | Conversion segmented by traffic source | Channel conversions / Channel visits |
| Conversion | 7. Cart abandonment rate | Users who start checkout and do not complete | (Abandoned carts / Created carts) x 100 |
| Conversion | 8. Lead-to-Customer Rate | Percentage of leads that become customers | (New customers / Total leads) x 100 |
| Retention | 9. Retention rate | Percentage of customers who repeat | (Repeat customers / Total customers) x 100 |
| Retention | 10. Churn Rate | Percentage of customers who stop buying | (Lost customers / Customers at start of period) x 100 |
| Retention | 11. NPS (Net Promoter Score) | Satisfaction and likelihood of recommendation | % Promoters - % Detractors |
| Revenue | 12. ROAS (Return on Ad Spend) | Return for each euro invested in advertising | Ad revenue / Ad spend |
| Revenue | 13. AOV (Average Order Value) | Average value of each order | Total revenue / Number of orders |
| Revenue | 14. CLV (Customer Lifetime Value) | Total value a customer generates over their lifecycle | AOV x Purchase frequency x Average customer lifespan |
| Revenue | 15. Revenue per Visitor (RPV) | Average revenue generated per visitor | Total revenue / Unique visitors |
Below, we go deeper into each category with practical context.
Acquisition indicators measure the efficiency with which you attract new users and leads to your digital ecosystem.
CPA is arguably the most direct KPI for evaluating the efficiency of your acquisition investment. Divide everything you have invested (advertising, content, tools, team) by the number of new customers acquired.
The important nuance is defining what counts as "investment". If you only include ad spend, you get a partial CPA. For a complete view, also include content production costs, automation tools and team time.
Similar to CPA, but measures the cost of generating a lead (not a customer). It is especially relevant in B2B models where the sales cycle is long and there are multiple steps between the lead and the purchase.
A low CPL is not necessarily good if the leads are low quality. You should always cross-reference CPL with the Lead-to-Customer Rate to get the full picture.
The volume of visits from organic searches is an indicator of the health of your content strategy and your search engine visibility. Unlike paid traffic, organic traffic is cumulative: the content you publish today can continue attracting visitors for years.
CTR measures the effectiveness of your titles, descriptions and creatives at generating clicks. A low CTR on your ads indicates a relevance or creative problem. A low CTR in organic results may indicate that your meta titles and descriptions are not optimised.
This is where CRO takes centre stage. Conversion KPIs measure the effectiveness with which you transform visitors into customers or qualified leads.
The percentage of visitors who complete the target action. It is the most universal KPI in CRO and probably the one with the greatest business impact. A 1% improvement in conversion rate can translate into thousands of euros in additional revenue without increasing traffic or ad spend.
The overall conversion rate is useful as a global indicator, but to make decisions you need to segment it by channel. Organic search traffic typically has a different conversion rate than social media traffic or email marketing traffic.
Segmenting by channel lets you identify where your best opportunities lie and where there are alignment problems between the user's expectation and the experience on your website.
In ecommerce, this KPI is critical. The global average cart abandonment rate hovers around 70%, meaning 7 out of 10 users who add a product to the cart do not complete the purchase. Every percentage point you reduce in abandonment has a direct revenue impact.
For B2B models or those with a long sales cycle, this KPI connects marketing to sales. It measures what percentage of the leads you generate end up becoming paying customers. If you generate many leads but few convert, the problem may be in lead quality or the nurturing process.
Acquiring a new customer is between 5 and 25 times more expensive than retaining an existing one. Retention KPIs measure your ability to keep customers active and satisfied.
The percentage of customers who make a repeat purchase within a given period. A healthy business has a growing or, at minimum, stable retention rate. If it drops, you need to investigate what has changed in the customer experience.
The other side of retention. Churn rate measures the percentage of customers you lose. In subscription models, it is the most critical KPI: a monthly churn of 5% means you lose more than half your customer base in a year.
NPS measures satisfaction and likelihood of recommendation. It is calculated by asking customers "on a scale of 0 to 10, how likely are you to recommend our company?" and subtracting the percentage of detractors (0-6) from the percentage of promoters (9-10).
Ultimately, it all comes down to this: how much your business earns relative to what it invests. These KPIs directly connect marketing to financial results.
Return on ad spend. If you invest 1,000 euros and generate 5,000 euros in attributed sales, your ROAS is 5x. It is the KPI that best connects ad investment with business results.
The average value of each order. Increasing AOV is one of the most effective levers for growing revenue without needing more traffic. Strategies like upselling, cross-selling and free shipping thresholds are classic CRO tools for improving this indicator.
The total value a customer generates throughout their entire relationship with your company. It is the KPI that puts CPA in perspective: you can afford a high CPA if the CLV is large enough.
Revenue per visitor combines conversion rate and AOV in a single metric. It is especially useful for evaluating A/B tests, as it captures both changes in conversion and in order value.
Do not start with KPIs, start with objectives. If your quarterly goal is to increase revenue by 20%, the relevant KPIs will be different than if your goal is to reduce churn by 10%.
A dashboard with 50 metrics is not a dashboard, it is noise. Select between 5 and 10 KPIs covering the four categories (acquisition, conversion, retention, revenue) and make sure each one has a clear target.
Not all KPIs need to be reviewed with the same frequency. Conversion rate can be reviewed weekly. CLV is a monthly or quarterly indicator. NPS can be measured every quarter.
The biggest challenge is not defining KPIs, but connecting data sources to measure them. Make sure your web analytics, CRM, email platform and ad tool are integrated to provide a unified view.
As we explore in depth in our guide on data-driven marketing, data-based decision-making requires not just measuring, but measuring the right things and acting accordingly.
If you had to choose a single category of KPIs to track, choose conversion. The reason is simple: conversion is the point where marketing translates into business results.
You can have spectacular organic traffic (acquisition), enviable retention and growing revenue. But all of that rests on conversion. Without conversion, traffic is just a nice number on a dashboard. Without conversion, retention has no customers to retain.
Conversion KPIs tell you whether your website, your landings and your user flows are doing their job: transforming visitors into customers.
Likes, followers and impressions are activity metrics, not impact metrics. They can be useful as secondary indicators, but they should not be your main KPIs.
A KPI without a target is just a metric. "Our conversion rate is 2.3%" is not actionable. "Our conversion rate is 2.3% and our target is 3% by Q4" is.
Consistency is key for identifying trends. If you change your KPIs constantly, you will never have a long enough time series to detect patterns and make informed decisions.
Averages hide reality. Your overall conversion rate might be 3%, but if you segment by device you discover it is 1.5% on mobile and 5% on desktop. That difference is a huge optimisation opportunity.
Defining and measuring KPIs is the first step. The step that actually generates value is acting on them. Every KPI below its target is an improvement hypothesis waiting to be formulated and tested.
If you need help defining your conversion KPIs, setting realistic targets and designing a data-driven optimisation programme, at Boost we are a consultancy specialising in conversion. We work with marketing teams to transform metrics into decisions and decisions into measurable results.
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