Pie Chart Maker

A pie chart only works when every slice is measured against the same real total. Imagine a class survey with 24 votes for reading, 18 for games, and 8 for drawing. The total is 50. Reading takes 24 / 50 = 48% of the circle, so its angle is 24 / 50 x 360 = 172.8 degrees. Games takes 129.6 degrees and drawing takes 57.6 degrees. Add the three angles and you get exactly 360 degrees: one complete circle.

This tool applies that value / total x 360 rule to every positive row after validation and optional grouping. Sorting changes where a slice appears, not its size. Switching from pie to doughnut removes the middle of the drawing, not part of the data, so the angles stay identical. Pulling out a slice changes only its position.

Displayed percentages need one extra step. Three equal values have raw shares of 33.333...%. Showing each as 33.3% would make the labels add to 99.9%. The tool first rounds down to tenths, then gives the remaining tenth to the slice with the largest discarded fraction. The labels become 33.4%, 33.3%, and 33.3%. They add to 100.0%, while the slice geometry still comes from the original one-third values.

Open the arithmetic table under your chart when students need to show their working. It prints each value, the real total, the displayed percentage, and the exact angle rule side by side.

A colour chart can collapse into a row of similar grey slices on a classroom printer. This maker gives every slice more than a colour: a repeating pattern, a dark outline, a letter key, and a legend entry with the category, value, percentage, and angle. A student can match A on the circle to A in the legend even when two fills print at nearly the same shade.

• Print for a handout or display. The shared print layout uses black on white, landscape Letter or A4 paper, and clean page isolation. Up to twelve legend entries stay with the chart. A longer legend starts on a fresh page so neither the chart nor the text is squeezed into unreadable type.
• SVG for worksheets, posters, and documents that may be resized. SVG stores paths and text rather than a fixed pixel grid, so edges stay sharp and the file remains editable.
• PNG for slides, online classrooms, and applications that expect a standard image. It exports on a white background at high resolution.

For the cleanest small chart, keep the legend on and let the letter keys do the labelling. Very narrow slices deliberately skip an on-slice key when it would collide with a neighbour, but their exact value and percentage remain in the legend and arithmetic table.