Pie Chart Maker with Percentages

Two ways to enter your data

You already have percentages

Choose Percentages above the rows and type 40, 35, 25. Below the rows a counter shows the running total. It turns green at 100%, and tells you how much is missing ("need 10% more") or how much you're over. When you add a new row, it's filled with whatever is left to reach 100.

You have raw numbers

Choose Values and type the counts as they are: 9 votes, 7 votes, 6 votes. Then set Show on chart to %. Each slice now shows its share of the total, and you never have to do the division yourself. Switch it back to Values and the slices show the counts again.

How the percentages are calculated

Each slice is its value divided by the total of all values, times 100. For the fruit survey in the editor, 27 students answered:

If your numbers are in a spreadsheet, the same calculation is =B2/SUM(B$2:B$5), formatted as a percentage.

Why the labels add up to 99.9%

Look at the total row. Every label is rounded to one decimal, and in this case all four got rounded down a little, so they add up to 99.9% instead of 100%. The slices themselves are drawn from the exact values, so the chart is still correct. Only the printed numbers are rounded.

If a teacher or a client will add up your labels, you have two options. Leave it and add a note like "percentages may not add up to 100 due to rounding", which is what newspapers and statistics offices do. Or switch to Percentages and type the rounded numbers yourself, bumping the largest slice by 0.1 (33.4 instead of 33.3).

When your percentages don't add up to 100

In Percentages mode the chart always fills the whole circle, whatever the total is. If you type 40, 30 and 20, the counter says you need 10% more, but the three slices are stretched to fill the space, so each looks bigger than its label says. Fix the total before you download:

• Something is missing. Add a row for it. It gets the missing 10% automatically. Name it "Other" if it's a mix of small things.
• The total is over 100. Usually this is a multiple-choice survey where people could pick more than one answer. Those answers don't split one whole, so a pie chart is the wrong chart for them. Use a bar chart.
• It's a rounding leftover of 99 or 101. Adjust the largest slice by 1.