Conversion rate optimisation (CRO) is the systematic process of increasing the percentage of visitors who take a desired action on your website or app - without necessarily increasing your traffic. That action could be a purchase, a form submission, a phone call, a free trial sign-up, or any goal your business cares about.
The word optimisation is important. CRO is not guesswork, and it's not 'making your buttons bigger.' It's a structured, evidence-driven discipline that uses behavioural data, user research, and controlled experiments to find and fix the friction between a visitor arriving and a conversion happening.
Plain English definition
CRO answers one question: of everyone who visits this page, why aren't more of them doing what we want? Then it tests fixes.
The conversion rate formula
Conversion Rate Formula
Conversion Rate = (Conversions ÷ Total Visitors) × 100
Express the result as a percentage.
Worked example: in one month your product page receives 8,400 visitors. Of those, 168 complete a purchase - a 2.0% conversion rate. You run an A/B test, conversions rise to 235. New rate: 2.8%. That 0.8 percentage point lift is a 40% revenue increase from the same traffic. No extra ad spend.
Why CRO matters
Editorial note on benchmarks
There is no universal CRO benchmark. Conversion rates vary by offer, audience, device, traffic source, and the definition of a conversion. Treat the worked examples in this guide as illustrations, then use your own historical rate as the baseline.
For a useful benchmark to be credible, it needs context. Unbounce's 2024 Conversion Benchmark Report is a good example: it analysed more than 41,000 landing pages, 464 million unique visitors, and 57 million conversions over the preceding year. That scale makes the findings useful as directional evidence, but it still does not turn an industry average into a target for every page.
+41K
Landing pages analysed
+464M
Unique visitors
+57M
Conversions
The report also reinforces why one blended conversion rate can mislead. In some industries, mobile brings up to seven times more visitors than desktop while converting at a lower rate. Break your reporting down by device, traffic source, industry, and conversion definition before deciding whether performance is strong or weak.
Benchmarking guidance: Google Analytics: mark events as key events
External benchmark report: Unbounce Conversion Benchmark Report (2024)
What's covered in this series
This pillar breaks the full CRO process into four focused guides - each one a standalone read you can act on immediately.
CRO Series
- Conversion Rate Formula, Benchmarks & ExamplesHow to calculate your conversion rate correctly, compare it to industry benchmarks, and understand what 'good' looks like for your specific context.
- Macro vs Micro Conversions: What to Track and WhyThe difference between primary conversion goals and the smaller signals that reveal where visitors are dropping out - and why tracking both changes your testing strategy.
- CRO Research Methods: Finding What's Actually BrokenThe quantitative and qualitative methods that surface the real reason visitors aren't converting - before you spend a single hour on a test.
- What to Test First: A CRO Prioritisation GuideA practical ranking of the highest-impact elements to test, the frameworks to prioritise your backlog, and the common mistakes that waste testing budgets.
Crow automates the research phase of CRO - scoring your landing pages, surfacing friction points, and prioritising what to test first. Run a free audit on your page and get a prioritised list of fixes in under 60 seconds.
