The Complete Guide to Conversion Rate Optimisation
Conversion rate optimisation (CRO) is how you turn the traffic you already have into more revenue. It's the highest-leverage growth work most teams neglect. This guide walks through the full CRO loop — audit, prioritise, test, ship — and links to the tools that make each step easier.
What is CRO, really?
CRO isn't "make the button bigger". It's a disciplined loop: measure where visitors drop off, hypothesise why, test the fix, and roll out the winners. Done right, a modest 15–25% CVR lift is transformative — try it in the website ROI calculator to see what it's worth to your business.
Step 1 — Audit the full journey
Start with the funnel. Every step from landing page to confirmation is a leaky bucket. Use your analytics to find the pages with the highest exit rate relative to their traffic. Then walk the journey yourself on mobile — most conversion killers live on mobile checkout, not desktop.
This is what Thrivio Lens automates: it audits every page, scores the issues by impact, and shows you the exact steps costing you conversions.
Step 2 — Prioritise ruthlessly
Most teams die from too many small tests. Rank opportunities by:
- Expected impact — traffic × current CVR × plausible lift
- Confidence — how strong is the evidence?
- Effort — copy swap vs. new design vs. dev sprint?
The top of the list should be high-traffic pages with clear evidence and low effort. Everything else waits.
Step 3 — Test properly
Before running an A/B test, calculate the sample size you need. Underpowered tests either miss real wins or call noise as a win. Use the statistical significance calculator to plan the test, and the A/B test significance checker to evaluate the result.
Rules of thumb:
- Never call a test before your pre-calculated sample size
- 95% confidence, 80% power is the standard
- Test one change at a time on high-traffic pages; batch minor changes on low-traffic ones
Step 4 — Ship the winners, roll back the losers
A winner isn't "ship it and move on". Roll it out gradually, monitor the segment-level impact (does it still work on mobile? on paid traffic?), and document what you learned. The compounding value of CRO comes from the second-order lessons, not the individual wins.
The most common CRO wins
Across hundreds of audits, the same wins keep appearing:
- Message-match between ad and landing page
- Single, clear CTA above the fold
- Address / postcode lookup in checkout
- Social proof near the primary CTA, not buried in a footer
- Mobile speed — every 100ms of LCP costs conversions
Measure the right thing
CVR alone lies. A drop in CVR with a rise in AOV can be a net win. Always track:
- Conversion rate (calculator)
- Revenue per visitor
- Bounce / engagement rate (analyser)
- Return on ad spend for paid traffic (ROAS calculator)
Where Thrivio fits
Thrivio runs the audit, scores the opportunities, drafts the experiment brief and even mocks up the variant in Studio. It's the CRO loop, condensed into one workspace — see Opportunities for how the backlog works.
CRO isn't a project. It's a habit. Start with one page, one test, and one clear next step.