Complex report and dashboard charting
Key Takeaway
Pick the chart that answers the business question. Use a line chart for how a value changes across ordered time periods, bar and pie charts to compare values at a point in time, and a combination chart for several measures on one chart.
Report and dashboard charts turn grouped report data into a picture, so users can see a trend or comparison before they read the rows. As an admin, you pick the chart type that fits the business question. Some requirements are harder, such as two measures on one chart or a second axis. For those, you use combination charts and dashboard widget settings. When you know each chart's rules and limits, you can predict what a given configuration will show.
Where charts appear
A report chart appears just above the report table. Charts can also appear in dashboard widgets. You can add a chart to any report grouped by rows (a summary report) or by rows and columns (a matrix report).
You can embed up to two report charts per page. You add them only from the enhanced page layout editor. In Lightning Experience, an embedded chart shows the source report table's groupings, not the report chart's groupings. In Salesforce Classic, an embedded chart shows the report chart's groupings.
Historical trend reports in Lightning Experience support charts. Tabular views aren't available for these reports. You must set the snapshot date as the primary row grouping.