How to Choose a CRO Agency That Moves Revenue, Not Just Conversion Rate
Conversion rate is a means to an end. The right CRO agency understands the difference - and tests toward revenue, not just rates.
A CRO agency (conversion rate optimisation agency) manages the process of identifying friction in your funnel and running experiments to remove it - increasing the percentage of visitors who convert into customers or leads. The best ones increase revenue. The worst ones optimise a metric while ignoring what the metric is actually for.
Through The Glass Creatives integrates CRO into growth programmes where the traffic-to-revenue gap represents meaningful opportunity. The industry has seen the output of both high-performing and underperforming CRO agencies - here's what the difference looks like before you sign.
Read conversion rate optimization services explained for a breakdown of deliverables and pricing before evaluating agencies. And if you're building a full growth stack, growth marketing services covers how CRO fits alongside paid, email, and SEO.
What Separates High-Quality CRO Agencies from Average Ones
They start with qualitative research - user interviews, session recordings, support ticket analysis - before writing a single test hypothesis
They document test hypotheses with clear rationale: observation → hypothesis → predicted outcome
They calculate required sample sizes before running tests - not stopping tests when they "look positive"
They report on revenue impact - average order value, revenue per visitor - not just conversion rate
They build a testing backlog that evolves with learnings - not a static roadmap
Red Flags in a CRO Agency Pitch
They guarantee a specific conversion rate improvement without knowing your traffic volume or current rate
Their case studies only show percentage improvements, not absolute revenue or lead volume change
They don't ask about your traffic quality or acquisition sources before scoping
They can't explain statistical significance in plain language
Their "testing" is really just design changes deployed without controlled experiments
Questions to Ask Before Hiring
Walk me through the last test you ran - what was the hypothesis, how did you measure it, and what was the revenue impact?
How do you handle tests that reach significance but show contradictory results on different metrics?
What traffic volume do you require before you'll recommend an A/B testing programme?
Who writes the copy for test variations - an in-house copywriter or a strategist?
"A CRO agency that reports on conversion rate without reporting on revenue per visitor is hiding the full picture. Conversion rate can go up while revenue per visitor goes down - that's not optimisation, that's noise." - Mherie Vic Prevendido, TTGC
Choose TTGC if / Choose a CRO Specialist if
Choose TTGC if you need CRO integrated with your brand strategy, paid media, and email programme - we optimise the full funnel, not a single page in isolation. Choose a CRO-only specialist if your site has 50,000+ monthly sessions, you're running tests continuously, and you need a team entirely focused on experimentation infrastructure and statistical rigour.
Sources
- CXL Institute - "CRO Agency Evaluation Guide." CXL, 2025.
- VWO - "How to Choose a CRO Agency." VWO Blog, 2025.
- Optimizely - "Experimentation Programme Maturity Model." Optimizely, 2026.
Ask TTGC whether your funnel is ready for CRO - we'll tell you honestly.
Book a free Brand and Growth Assessment and see exactly how Through The Glass Creatives would approach it.
