The essentials
- Definition: CRO (Conversion Rate Optimization) is the discipline of increasing the share of visitors who take the action you want, without increasing traffic.
- Why it matters: going from 2% to 2.5% conversion produces the same result as 25% more traffic, at a far lower cost and with a lasting effect across every channel.
- The method: measure, find the leaks, form a hypothesis, test, roll out; all in short cycles.
- 2026 benchmarks: a structured programme gains 10 to 30% more conversions in six months on a site that has never been optimised.
The aim of CRO (Conversion Rate Optimization) covers every method for increasing the proportion of visitors who take the action you want: a purchase, a quote request, a booking, a sign-up. It isn't about bringing more people in but about losing fewer along the way. It is digital marketing's most profitable lever, because its effect applies to all your existing traffic, whatever its source, and it isn't paid for by the visit. The metric itself is covered in conversion rate: definition.
Why CRO pays better than traffic
| Situation | Visitors | Rate | Conversions | What the action costs |
|---|---|---|---|---|
| Starting point | 10 000 | 2 % | 200 | Baseline |
| + 25% paid traffic | 12 500 | 2 % | 250 | Several thousand euros a month, recurring |
| + 0.5 point of conversion | 10 000 | 2,5 % | 250 | A few days of work, a permanent effect |
| Both | 12 500 | 2,5 % | 313 | The conversion gain multiplies your acquisition |
The method in five steps
- Measure: conversion rate by source, device, landing page and funnel step. An overall rate says nothing; the gap between mobile and desktop, often 30 to 50%, already points to a project. Breaking the journey into steps is set out in the AARRR funnel. The analysis is described in analysing a conversion funnel with GA4.
- Find the leaks: the steps where the progression rate collapses, abandoned forms, slow pages, errors on mobile. Session recordings and click maps complete the figures with observation.
- Form a hypothesis: "visitors abandon the form because it asks for eleven fields including a company registration number; cutting it to four fields will raise the submission rate by 20%". A hypothesis names a cause, an action and an expected effect.
- Test: an A/B test where volume allows, a straight release with before-and-after measurement where it doesn't. The testing method is set out in A/B testing.
- Roll out: apply what worked to the other pages of the same type, document what failed, start again. A CRO programme lives on repetition; the full plan is in improving your conversion rate.
The levers that work
- Clarity of the offer: what you sell, to whom, at what price, visible without scrolling; this is the first factor, far ahead of button colour.
- Reducing friction: fewer fields, optional account creation, one-click payment, the ability to go back.
- Proof: reviews, testimonials, figures, client logos, guarantees — placed at the moment of doubt rather than all at the bottom of the page.
- Speed: every extra second of load time costs 5 to 15% of conversions; see the Core Web Vitals.
- Consistency with the source: a landing page that carries through the ad's promise converts two to three times better than a generic home page; see landing page.
- Mobile first: most of the traffic, often a minority of the conversions; fixing mobile is the project with the best return.
- Answering objections: shipping costs, timescales, commitment, security — addressed explicitly rather than left hanging.
What CRO is not
It is not a collection of universal tricks: a button colour or a countdown timer produce no lasting gain, and devices that force people's hand damage the relationship and the return rate. Nor is it a redesign: changing the whole site at once makes it impossible to know what produced the effect. Finally, CRO doesn't make up for an ill-suited offer or badly targeted traffic: a visitor arriving from a misleading ad won't convert, whatever the page. The benchmarks by sector are in e-commerce KPIs.
How GreenRed helps
Rather than juggling several tools, GreenRed's Site health module brings these metrics together in a single dashboard, compares them over time and tells you which actions come first. You can try it free, with no card, from the Pricing.
Frequently asked questions
What is CRO?
Conversion rate optimisation: every method that increases the share of visitors taking the action you want (a purchase, a quote, a sign-up), without increasing traffic. Its effect applies to every traffic source and isn't paid for by the visit.
What gain should you expect from a CRO programme?
10 to 30% more conversions in six months on a site that has never been optimised, more if mobile has been neglected. A 0.5-point gain on a 2% rate is the equivalent of 25% more traffic, at a far lower cost and with a permanent effect.
Do you need A/B tests?
When volume allows: you need several hundred conversions per variant to conclude anything. Below that, you release the version you judge better and compare the periods before and after, allowing for seasonality. A test without enough volume produces false conclusions.
Where do you start with CRO?
By measuring conversion rate by device, source and landing page, then walking the whole funnel on mobile in real conditions. The friction found that way, along with load speed, gives you your first projects, before any testing.