Streak Simulator: How Streaky Is Ordinary Luck?

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Number of tries

Chance of success each try %

Run length to look for

Count runs of

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Enter your numbers, then press Calculate.

From the book, Chapter 7. In 100 fair flips the chance of a run of six or more is 80.7%; a longest run of four or less, typical of made-up lists, has only 2.8%. The longest run averages 7.0 in 100 flips and 10.3 in 1,000. A team that wins 60% of its games has a 64.4% chance of a five-game winning streak in a 30-game season.

Exact figures are counted, not simulated; the buttons play it out with your browser’s random numbers, so they differ a little each time. Everything stays in your browser: no sign-up, nothing stored or sent.