Launching a redesign without a baseline is like flying blind. You will never be able to prove that your project delivered results if you haven't captured a snapshot of the starting point. A well-built baseline lets you objectively measure the impact of your changes and justify your investment to leadership.
Why your baseline determines the measurable success of your project
Without a baseline, no impact measurement is possible
Many redesign projects never measure their return, because no reference data was collected before launch. Without an initial snapshot, comparing before and after stays an impression.
It is essential to define clear and measurable goals (KPIs) from the strategy and preparation phase. This step determines your entire ability to prove the value of your project.
The baseline protects you from perception bias
Teams often overestimate the real improvement because they poorly remember the initial situation. A documented baseline neutralizes this bias by setting objective numbers.
It also helps you detect seasonal variations: if you launch in January and compare with December, you risk confusing project effect with calendar effect.
It turns your project into a credible case study
Establish your reference metrics before any redesign: current traffic, conversion rate, SEO rankings, speed. They are what will give meaning to the numbers that follow.
These numbers mean nothing without a baseline: you need to prove where you started to showcase where you end up.
The essential data to capture in your baseline
Traffic and acquisition sources
Collect for a minimum of 2 to 4 weeks (ideally 3 months to smooth out seasonality):
- Total sessions and unique users
- Traffic by channel (organic, direct, referral, social, paid)
- Page views and overall bounce rate
These metrics show you whether your redesign improves or degrades the visibility and attractiveness of your site.
SEO performance and rankings
Complete snapshot of your organic rankings:
- Number of keywords ranked (top 3, top 10, top 50)
- Monthly organic traffic
- Referring domains and active backlinks
A poorly prepared redesign can knock your organic traffic down hard if URLs and redirects are not mapped correctly. It is the most common risk, and the slowest to recover from.
Conversion and engagement
For each important business objective:
- Overall conversion rate and per landing page
- Average conversion value
- Time on site and navigation depth
Google Analytics 4, Hotjar, or Matomo are sufficient for most projects to evaluate your site with powerful analytics tools.
Technical performance
Measure loading speed before any modification:
- Core Web Vitals (LCP, FID, CLS) via PageSpeed Insights
- Server response time (TTFB)
- Weight of main pages
It is essential to evaluate your starting point in terms of speed and then set realistic performance goals. Without this technical baseline, you cannot prove UX improvement.
The fatal trap: a baseline that is too short or too broad
Less than 7 days of data = unreliable baseline
One week of data rarely captures the normal variations in your activity. If you measure during an exceptional peak or dip, your baseline will be skewed.
Our recommendation: 2 weeks minimum for an express baseline, 1 month ideal, 3 months to eliminate any seasonal effect.
Too many KPIs kill the measurement
A redesign requires thorough preparatory work. But be careful: listing 50 indicators dilutes your attention and complicates post-launch reading.
Focus on 8 to 12 KPIs maximum, directly tied to your business objectives: traffic, conversion, SEO, speed. The rest is noise.
Forgetting the external context
Your baseline must include external events that influence your metrics: active paid campaigns, business seasonality, competitor actions, Google algorithm changes.
Note these elements in a separate document: they will help you interpret gaps between baseline and post-launch.
How to organize your baseline collection in 1 to 2 weeks
Week 1: extraction and centralization
Set up your measurement tools if not already done:
- Google Analytics 4 with conversion goals activated
- Google Search Console for SEO
- PageSpeed Insights or GTmetrix for performance
Export data from the last 3 months (or at minimum the last 30 days). Centralize everything in a shared Google Sheet or Looker Studio.
Week 2: validation and documentation
Verify the consistency of your data:
- Compare GA4 figures with those from your CRM or e-commerce tool
- Check that peaks/dips correspond to known events
- Identify and document anomalies (bug tracking, exceptional campaigns)
Write a "Baseline [Project Name] - [Date]" document that lists:
- The 8 to 12 selected KPIs
- Their average value over the period
- External context (seasonality, active campaigns)
Concrete action: create your baseline dashboard
Use this template to structure your baseline:
| KPI | Period | Average Value | Min | Max | Source |
|---|---|---|---|---|---|
| Sessions | 02/01-02/28 | 45,230 | 38,100 | 52,400 | GA4 |
| Conversion rate | 02/01-02/28 | 2.3% | 1.9% | 2.7% | GA4 |
| Keywords top 10 | 02/28 | 127 | - | - | GSC |
| LCP (median) | 02/01-02/28 | 2.8s | 2.4s | 3.3s | PSI |
Share this file with all project stakeholders before launch.
