What it is
A funnel chart draws each stage of a process as a band whose width is proportional to its count, centred so the shape narrows like a funnel. The drop between bands is how many were lost at that step.
✓ Use it when
- You have an ordered process where each stage is a subset of the one before: visitors → sign-ups → trials → purchases.
- You want to show where the biggest drop-off happens.
✗ Avoid it when
- The stages are not subsets of each other — use a bar chart.
- Precise comparison matters — sorted bars carry the same information on a common baseline.
Tips for a better chart
- Order the stages as the process runs, from the top.
- Add the conversion rate between stages in the labels or subtitle: it is usually the real story.
- Keep the number of stages small, four to seven.
The maths
Stage conversion is ck = nk/nk−1, and overall conversion is the product of the stage rates, nK/n1 = Π ck. A small improvement at a narrow stage can therefore move the end result more than a large one at a wide stage.
A little history
The funnel comes from sales theory rather than statistics. The AIDA model — attention, interest, desire, action — is commonly credited to the advertising pioneer E. St. Elmo Lewis around 1898, on the account of the psychologist E. K. Strong (Strong 1925). Picturing the stages as a narrowing funnel followed, and the funnel chart became a fixture of web analytics with online conversion tracking.
Questions
Does my data need to be sorted?
Chart Buffet sorts the stages from largest to smallest by default. If your process can grow between stages, it isn’t really a funnel; use bars.
References
- Strong, E. K. (1925). Theories of selling. Journal of Applied Psychology 9(1), 75–86.
- Strong, E. K. (1925). The Psychology of Selling and Advertising. New York: McGraw-Hill.
- Wikipedia contributors (2026). AIDA (marketing). Wikipedia.