The essentials
- The basic rule: a line for a trend, bars for a comparison, a figure with its gap for a status, a table for the detail; the rest is rare.
- To avoid: the pie chart beyond three slices, the radar for different units, the double scale, the gauge without a target, the 3D chart.
- Readability: 6 to 8 visuals per screen, one question per chart, the target visible, colours limited to three meanings.
- Heatmap: useful for days and hours (posts, calls, sales) and for page funnels; useless for comparing channels.
The same indicator can be read in two seconds or in two minutes depending on how it is represented. Choosing the chart is not a matter of taste: each type of question (is it going up, who is best, where do we stand, where is the problem) has a visual shape that answers it better than the others. This article gives the match between types of KPI and charts, the readability rules and the representations to avoid. It complements creating a clear dashboard for a leadership team and adding target objectives to your dashboard.
Four questions, four shapes
| The question asked | Representation | Example KPIs |
|---|---|---|
| How is it changing? | Line chart, with a target line and the previous period in grey | Sessions, leads, revenue, positions, cost per lead over time |
| Who is best? What share? | Sorted horizontal bars, stacked bars for the split | Leads by channel, cost per result by campaign, share of sources |
| Where do we stand? | Key figure with the gap to target and the variation, gauge or progress bar for a cumulative total | Leads for the month, net ROAS, conversion rate, progress towards the annual objective |
| Where is the problem? | Sorted table with conditional formatting, heatmap, funnel | Pages in decline, days and hours of conversion, funnel steps |
The useful charts, one by one
- The line chart: the most widely read representation. One to three series at most, the target as a dotted line, the previous year in light grey, events annotated (campaign, outage, promotion). A weekly line smooths out the daily noise.
- Horizontal bars: for comparing categories (channels, campaigns, pages). Sorted by value, with full labels and a single colour except to flag whether the target has been met. Vertical bars suit periods (months) when the line chart is too flat.
- 100% stacked bars: for a split over time (the share of channels month by month). Limited to five segments, otherwise the small shares become unreadable.
- The key figure: a value, the gap to target as a percentage, the variation against the previous period, a sparkline over 12 periods. It is the top block of a leadership dashboard.
- The gauge and the progress bar: for a cumulative total towards an objective (annual revenue, leads for the quarter), with the expected progress at today’s date. Without a target, they serve no purpose.
- The table: for the detail and the diagnosis: 10 to 30 sorted rows, two or three numeric columns, conditional formatting (colour according to the gap). A well-sorted table is often worth more than a chart.
- The funnel: for a conversion funnel with three to six steps, with the pass-through rate between each step; funnel analysis is detailed in analysing a conversion funnel with GA4.
- The heatmap: for two crossed dimensions (day of the week and hour: conversions, calls, post engagement; or page and device). It shows concentrations, not precise values.
The representations to avoid
| Representation | Problem | Replace with |
|---|---|---|
| Pie or doughnut beyond 3 slices | The eye compares angles poorly; the small slices are unreadable | Sorted horizontal bars |
| Radar (spider chart) | Compares different units on a single scale; the surface area misleads | Score table or bars by criterion |
| Double vertical axis | Two scales, a false reading of the crossing points | Two separate line charts, or a ratio (cost per lead) |
| 3D chart, effects, gradients | Distort the proportions and slow down reading | A flat version, one colour |
| Daily line chart over 12 months | Unreadable noise | Weekly line chart or 7-day moving average |
| Scatter plot for a leadership team | Requires a statistical reading | Sorted table or bars; the scatter plot remains useful to the analyst |
| Gauge without a target, speedometer | No information, a lot of space | Key figure with its gap |
The readability rules
- One question per chart: the chart title is the question (“Leads by channel, last 30 days”), not the name of the metric.
- Six to eight visuals per screen: beyond that, the dashboard reads like a report; you add a page, not a chart.
- The target always visible: a dotted line, the gap as a percentage, or colour; a figure without a reference says nothing.
- Three meaningful colours: one for the main series, one for the comparison, one for the alert. Channel colours (Facebook blue, YouTube red) are acceptable if they stay consistent across the whole dashboard.
- The reading order: key figures at the top, trends in the middle, details and tables at the bottom; decisions are made at the top, explanations are looked for at the bottom.
- The same period everywhere: a dashboard mixing 7 days, 30 days and the quarter on the same screen is misleading.
- Accessibility: sufficient contrast, no information carried by colour alone (add a symbol or a label), text size readable on mobile.
A guide by marketing KPI
| KPI | Recommended representation | Useful detail |
|---|---|---|
| Sessions, users | Weekly line chart with last year | Bars by source underneath |
| Leads, sales | Key figure with its gap, monthly line chart with target | Sorted bars by channel |
| Cost per lead, CAC, ROAS | Key figure, line chart with a threshold line (maximum cost, break-even ROAS) | Bars by campaign |
| Conversion rate | Key figure, weekly line chart | Bars by device and by landing page |
| Funnel | Funnel chart with the pass-through rate | Table by segment |
| SEO positions, AI citations | Line chart of the number of keywords by position band (top 3, top 10) | Table of the pages rising and falling |
| Social engagement | Bars by format or by post | Heatmap by day and hour |
| Channel split | 100% stacked bars by month | Never a pie chart |
The ready-made templates in Looker Studio are presented in the best Looker Studio templates for GA4, and complete examples in examples of marketing dashboards.
How GreenRed helps
Rather than juggling several tools, GreenRed's overview brings these metrics together in a single dashboard, compares them over time and tells you which actions come first. You can try it free, with no card, from the Pricing.
Frequently asked questions
Which chart should you use for a marketing KPI?
A line chart for a trend over time, sorted horizontal bars to compare channels or campaigns, a key figure with its gap to target for a status, a sorted table for the diagnosis, a funnel chart for a conversion funnel, a heatmap to cross day and hour.
Why avoid the pie chart?
The eye compares angles and surface areas poorly: beyond three slices, the gaps between categories can no longer be read and the small shares disappear. Sorted horizontal bars give the same information with values that are readable and comparable.
Is the radar useful for comparing channels?
Rarely. It places indicators with different units (CTR, cost, volume) on a single scale and the resulting surface area means nothing. A score table or a series of bars by criterion is more accurate. The radar remains acceptable for scores normalised out of 10, an audit for example.
When should you use a heatmap?
For two crossed dimensions where you are looking for concentrations: day and hour of conversions, calls or post engagement; page and device; funnel step and segment. It is not suitable for comparing precise values between channels.
How many charts per dashboard?
Six to eight per screen, with one question per chart, the target visible and the same period everywhere. Beyond that, the dashboard becomes a report; you add a page per audience (leadership, marketing, campaigns) rather than charts on the same page.