Donut Chart Total is different between Classic and Lightning Experience
|Knowledge Article Number||000240421|
|Description||The number in the center of a Donut Chart in Classic, is the same number as that of the Grand Total on the report.
This functionality has been modified in Lightning Experience so that the Grand Total may not always match the number at the center of the Donut Chart.
|Resolution||In Classic, the number at the center of the Donut Chart is the same as the Grand Total on the report. Essentially, it applies the calculation of the Custom Summary Formula to the subtotals, resulting in the Grand Total.
In Lightning Experience, as well as on Salesforce1, the number at the center of the Donut Chart is a sum of the individual segments on the chart. The Grand Total is displayed separately; both at the top of the report, and at the end.
Note that Donut Charts do not currently support percentages in Lightning Experience.