How it works
This random percentage generator draws one of 101 whole percents, all equally likely. Split 100% gives a sum such as 38% + 31% + 5% + 26% = 100%, and Smallest part keeps every share above a floor.
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How the split stays fair
With Smallest part on 1, four parts need three cuts. The page draws three different cut points from 1 to 99 and takes the gaps: cuts at 38, 69 and 74 give 38, 31, 5 and 26. Every one of the 156,849 ways to write 100 as four whole parts has the same chance. A larger Smallest part works the same way on what is left after every part has its floor.
Percent, decimal and fraction
Percent means out of 100, so 35% is 0.35 as a decimal and 35/100, or 7/20, as a fraction. This page draws whole percents only. For a percent such as 37.42%, set Highest to 100 on the random decimal generator, which opens on two decimal places.
- Rolling a 30% chance? Use pick a number 1 to 100: 30 or less means yes. The 101 values here would skew it slightly.
- Set Smallest part to 0 and a part may come out as 0%. The opening setting of 1 never gives an empty share.
- To say a percent as a 1-in-N chance, divide 100 by it: 25% is 1 in 4 and 5% is 1 in 20.
Questions and answers
How does a percentage randomizer make pie chart data?
Tap Split 100%, set Split into to the number of slices and press. The slices total exactly 100, so the chart needs no rounding fix, and Copy gives the whole sum. Name the parts adds a label to each slice; names stay in your browser.
Are the parts of a random split roughly equal?
No. Every split is equally likely, but most are lopsided: with four parts the largest averages about 52%, the smallest about 7%, and half the splits have a part of 50% or more. Raise Smallest part to 15 and each lands between 15% and 55%.
Why does 0 to 100 hold 101 values and not 100?
Count both ends: 0, 1, 2 and so on up to 100 makes 101 numbers. That is why 0% and 100% can both come up here. For exactly 100 values, use the pick a number 1 to 100 page.