What this calculator does
A pie chart is really just arithmetic wearing a circle: every slice is a share of a total, expressed as a percentage, and that percentage sets how many of the circle’s 360 degrees the slice gets. This pie graph maker calculator does that arithmetic for any list of category values you enter, without drawing the chart itself.
Working out the numbers behind a pie chart is useful on its own, whether you are drawing one by hand with a protractor, building one in spreadsheet software, or just need to know what share each category actually holds. Enter the raw values for each category, in any order, and it returns the percentage and angle for every one of them plus the largest slice at a glance.
The formula
Add up every category value to get the total. Each category’s percentage is its own value divided by that total, times 100. Its angle is the same fraction of the full circle: the value divided by the total, times 360 degrees, since a circle has 360 degrees and a pie chart splits the whole of it among the categories.
| Term | Meaning |
|---|---|
| Total | The sum of every category value entered. |
| Percent of total | A category’s value divided by the total, expressed as a percentage. |
| Angle (degrees) | A category’s share of the full 360-degree circle: (value ÷ total) × 360. |
The inputs explained
| Field | What to enter |
|---|---|
| Category values (comma or space separated) | Enter each category’s value, separated by commas or spaces. Order does not matter, but the calculator numbers them in the order entered. |
When to use it
Drawing a pie chart by hand
A protractor needs degrees, not percentages. Converting each category to its angle first means the slices can be marked out directly on paper.
Checking a chart built elsewhere
If a spreadsheet or presentation tool has drawn a pie chart, recomputing the percentages independently confirms the slice sizes actually match the underlying data.
Summarising a survey or budget split
A budget split across several categories, or survey responses split across several options, is exactly the kind of list this calculator turns into shares and angles.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the slices split for an even four-way split versus an uneven one
The same four categories, entered with different relative sizes.
| Category values | Largest category share | Largest category angle |
|---|---|---|
| 25, 25, 25, 25 | 25.0% | 90.00° |
| 40, 25, 20, 15 | 40.0% | 144.00° |
| 70, 10, 10, 10 | 70.0% | 252.00° |
| 90, 5, 3, 2 | 90.0% | 324.00° |
Percentage and angle for a five-category budget split
A single worked example with five categories, showing every row of the breakdown table.
| Category values | Total value | Number of categories |
|---|---|---|
| 500, 300, 150, 100, 50 | 1,100.00 | 5 |
Questions
Does this calculator draw the actual pie chart?
No. It calculates the percentage and angle for each slice, which is the maths behind a pie chart, but it does not render the chart graphic itself. Those numbers plug directly into a protractor, spreadsheet chart tool or design software.
Why do the angles always add up to 360?
A full circle is 360 degrees, and every category’s angle is its share of that total. Since the percentages themselves add up to 100%, the angles, being the same shares of 360 instead of 100, always add up to the full circle.
Can I enter category values that are already percentages?
Yes. If your values already sum to 100, the percentage output will simply match what you entered, and the angle for each will still come out correctly as (value ÷ 100) × 360.
What if a value is entered as zero?
A zero-value category is allowed and will show as 0% and a 0-degree angle. It still counts as one of the categories in the total count, it simply takes no space in the chart.
For the mean, spread and quartiles of a raw data set instead of category shares, see the descriptive statistics calculator. To measure how varied a set of categories is, rather than just its shares, try the Simpson’s Diversity Index calculator.