A heat map (also written as heatmap) is a data visualization tool that overlays user behavior onto a webpage, using color gradients to show where visitors are most and least active. Hot colors (red, orange) indicate high activity; cool colors (blue, green) indicate low activity.
Heat maps are a qualitative research tool in CRO — they help diagnose where friction exists before you run quantitative experiments to fix it.
Types of Heat Maps
Click Maps
Show where visitors click on the page — including non-clickable elements, which often indicates confusion or unmet expectations. If users are clicking on a non-linked image that looks like a button, they expect it to do something.
Scroll Maps
Show how far down the page visitors scroll before leaving. If 80% of visitors never see your primary CTA because it's placed below the fold where only 20% scroll, a scroll map reveals that immediately.
Move Maps
Track mouse cursor movement as a proxy for eye tracking. Not perfectly correlated with where users look, but useful for identifying areas of visual interest and ignored sections.
Session Recordings
Not technically a heat map, but frequently offered alongside them. Session recordings are replays of individual user sessions that let you watch exactly how a specific visitor navigated your page.
How Heat Maps Support CRO
Heat maps answer different questions than analytics:
| Analytics Tells You | Heat Maps Tell You |
|---|---|
| How many people left | Where they were when they left |
| What the click rate was | What they tried to click that didn't work |
| Where traffic dropped off | Which section of the page caused the drop |
Heat maps are most valuable in the research phase of a CRO program — before you decide what to test. They surface the hypotheses worth testing.
Limitations
Heat maps aggregate behavior, which can obscure differences between user segments. A click map showing low CTA engagement might look very different for mobile versus desktop visitors — most heat map tools let you filter by device, which is essential.
Heat maps don't explain intent. A visitor who scrolls past your pricing section might have been highly interested but unconvinced, or they might have been looking for something else entirely. Session recordings and user surveys provide the "why" that heat maps alone can't.
Sampling bias. Heat maps typically sample a fraction of sessions, not all traffic. For low-traffic pages, sample sizes may be too small to draw reliable conclusions.
When to Use Heat Maps
Use heat maps when:
- Conversion rate is low and you don't know where the friction is
- You've run a page redesign and want to confirm users are engaging with new elements
- You suspect mobile visitors are having a different (worse) experience than desktop
- You want to validate or refute a hypothesis before investing in an A/B test