CVR (Conversion rate)

Key Performance Indicator (KPI) that measures the proportion of visitors who have carried out an expected action on a site or application, in relation to the total number of visitors exposed.
It is expressed as a percentage and is calculated by the formula :

CVR (%) = (Number of conversions ÷ Number of visitors) × 100

🎯 Why it's a central KPI:

CVR is the main evaluation criterion in most A/B or MVT tests, as it reflects the ability of a page, message or path to transform a visit into real value: purchase, lead, registration, strategic click, etc.

📌 Examples of shares recorded as conversions :

• E-commerce: order validated, added to basket, stock alert subscription,
• Lead gen / SaaS: submit form, request demo, create account,
• Content: download a guide, subscribe to a newsletter, watch a full video.

🔍 Role of the CVR in A/B testing :

When testing a variation, the aim is generally toincrease the CVR relative to the control version. The test makes it possible to determine, with a certain level of statistical confidence, whether the change has a positive, neutral or negative causal impact on this KPI.

The CVR is therefore the main KPI most often used for :

• evaluate the performance of a single variation (A/B test),
• compare several combinations of changes (MVT),
• measure the impact of dynamic or targeted personalization.

🧪 CVR & test structure :

• In an A/B test, we measure the CVR of the variation vs. that of the control to isolate the effect of a change.
• In an MVT test, each combination has its own CVR, and we analyze the individual or crossed impact of several elements (title + image + CTA, etc.).
• Visit CVR can be leading or lagging depending on the nature of the conversion :
  • Leading (e.g.: click on a button) → KPI quick to measure, useful for detecting early signals,
  • Lagging (e.g.: final purchase) → strategic KPI, but longer to observe.

✅ Best practices :

• Always combine CVR with other context metrics (e.g. bounce rate, revenue per visitor, segmentation by device or source),
• Check the statistical significance of the result before drawing a conclusion,
• Take into account the Minimum Detectable Effect (MDE ) to determine the minimum test duration,
• Cross-reference CVR with quality indicators (e.g., product return rate, churn rate if CVR lead).

📈 CVR ≠ absolute success :

A good conversion rate is only relevant if it is aligned with the business objective.
A very high CVR on an intermediate action (e.g.: click on "start now") can mask a disappointing performance on the final action (e.g.: paid subscription).
This is why CVR must be integrated into an overall reading of the funnel.

‍