How does best of five work?

Five rounds are available, and the first side to win three of them takes the series, so a game can end after three rounds rather than always running to five. The line under the coin says where it stands after every round: "2 to 1 after 3 rounds. First to 3 wins." Once a side reaches three the series is decided and no further flip can change it, so Flip round stops and New game becomes the button to press.

Why does the number of rounds have to be odd?

Because an even series can end level and there would be no winner to report. A best of four that finishes two apiece has no majority, and inventing a tie-breaker would mean the page deciding something the coin did not. The round count therefore takes any odd number from 1 to 99, and an even one is refused with a message saying to pick 3, 5 or 7 instead.

Is each round as fair as a single flip?

Every round uses crypto.getRandomValues from your browser, with an equal chance of heads or tails. Previous rounds do not influence the next draw. Being 2 to 0 down leaves the next round at 50 to 50.

Does the tally carry over between games?

The tally counts every flip on this game page, across series and mode changes, and is remembered here until Reset tally. New game clears the current series and leaves those counts alone. The main simulator has a separate saved tally. Opening either page only reads its record; flips and resets save immediately.

Can I go back to flipping a pile of coins?

Yes. Switch the mode from Best of to Flip and the count field comes back, taking any number of coins from 1 to 1000 in a single throw. The two modes share one tally, so a hundred coins thrown after a best of five are added to the same running count.

Can I play in a phone browser?

The same game controls run on a phone, tablet or computer with a current browser that supports crypto.getRandomValues. Nothing needs installing. Browser storage keeps this page's tally when available.

Coin Flip Game

Choose three, five or seven rounds and flip one round at a time until heads or tails takes the majority. This page starts on best of five, so either side needs three wins. The line under the coin reports the score after each round.

Best of 5

No rounds played yet. Best of 5, first to 3 wins.

Mode

Rounds

Heads

Tails

Heads share

0.0%

Longest run

none yet

Flips

Press Space to flip without reaching for the mouse.

Accuracy. A fair 50 to 50 draw from the browser's own cryptographic randomness, never a pattern or a seed. It cannot know anything about the decision you are making with it.

Common questions

How does best of five work?: Five rounds are available, and the first side to win three of them takes the series, so a game can end after three rounds rather than always running to five. The line under the coin says where it stands after every round: "2 to 1 after 3 rounds. First to 3 wins." Once a side reaches three the series is decided and no further flip can change it, so Flip round stops and New game becomes the button to press.
Why does the number of rounds have to be odd?: Because an even series can end level and there would be no winner to report. A best of four that finishes two apiece has no majority, and inventing a tie-breaker would mean the page deciding something the coin did not. The round count therefore takes any odd number from 1 to 99, and an even one is refused with a message saying to pick 3, 5 or 7 instead.
Is each round as fair as a single flip?: Every round uses crypto.getRandomValues from your browser, with an equal chance of heads or tails. Previous rounds do not influence the next draw. Being 2 to 0 down leaves the next round at 50 to 50.
Does the tally carry over between games?: The tally counts every flip on this game page, across series and mode changes, and is remembered here until Reset tally. New game clears the current series and leaves those counts alone. The main simulator has a separate saved tally. Opening either page only reads its record; flips and resets save immediately.
Can I go back to flipping a pile of coins?: Yes. Switch the mode from Best of to Flip and the count field comes back, taking any number of coins from 1 to 1000 in a single throw. The two modes share one tally, so a hundred coins thrown after a best of five are added to the same running count.
Can I play in a phone browser?: The same game controls run on a phone, tablet or computer with a current browser that supports crypto.getRandomValues. Nothing needs installing. Browser storage keeps this page's tally when available.

A fair 50 to 50 draw from the browser's own cryptographic randomness, never a pattern or a seed. It cannot know anything about the decision you are making with it.