Pie Chart Calculator

A pie chart is a circular part-to-whole display. Each category becomes a sector whose angle and area are proportional to that category's value divided by the sum of all values. Because a full circle contains 360 degrees, a category representing 25 percent of the total occupies a 90-degree sector. This calculator performs the normalization automatically, displays the resulting circle, and lists exact percentages beside the visual so that the proportions remain accessible and easy to verify. Pie charts work best when the categories are mutually exclusive, collectively describe one meaningful total, and number only a few. A simple budget divided into housing, food, and other spending is a good candidate. Three regional sales totals or three survey-response groups can also be understood quickly as slices. The chart is less effective when categories overlap, when values include negative numbers, or when the viewer needs to compare many similar values precisely. In those cases, a bar chart or table usually communicates differences more accurately. The calculator accepts raw positive values; they do not need to add to 100. It first sums all three entries and then divides every value by that total. For values 50, 100, and 50, the total is 200. Their proportions are therefore 25 percent, 50 percent, and 25 percent. The generated sectors use those ratios regardless of whether the original units are dollars, people, hours, votes, or counts. Units should be consistent across all categories because unlike quantities cannot form a coherent whole. Good labels are short, specific, and distinct. A legend entry such as Other may be useful for grouping small categories, but it should not conceal an important segment. Consider sorting slices from largest to smallest when preparing a formal presentation and use a consistent starting point if comparing several charts. Color should reinforce the labels rather than replace them; viewers may have color-vision differences, and printed output may lose hue distinctions. This tool always includes a textual legend with names, values, and percentages for that reason. A pie chart communicates composition at one point or for one defined group. It generally should not be used to show change over time, because comparing sector angles across multiple circles is difficult. A line chart is better for trends, and grouped bars are better for comparing category values across periods. Likewise, if exact ranking is the main message, the summary table may be more useful than the circle itself. Before sharing a chart, check that the total has a clear interpretation and that omitted categories do not distort the story. Values should come from the same measurement period and scope. Rounded percentages may visually sum to 99.99 or 100.01 even though the underlying proportions sum exactly to 100; that is a display-rounding effect, not a calculation error. The calculator retains full precision for drawing sectors and shows two decimal places in its readable summary.