Gambler's fallacy simulator: is red ever 'due'?
Predict how often a bet on the 'due' colour wins, then flip a fair coin by hand or 500 times at once. You will see streaks turn up often and the win rate on 'due' bets settle close to 50%.
How it works
The tool flips a fair two-colour coin: red and black each come up with probability 1/2, and every flip is drawn fresh, with no link to earlier ones. A 'due' bet backs the colour opposite to the latest result, so its chance of winning is 1/2 whatever the streak. Six reds in a row has a probability of 1/2 to the power 6, or 1 in 64, from any starting point, yet the seventh flip is still 50/50. Over n bets the win rate settles near 50%, with a typical wobble of the square root of (0.25 ÷ n), about 2.2 points after 500 bets.
You first predict the win rate of betting on the 'due' colour: below, about or above 50%. The chips then show the last 20 flips, and the line beneath names the current streak, such as 'Red · 3 in a row'. 'Bet it breaks' backs the opposite colour and is counted in the two readouts, 'due' bets placed and win rate on 'due'. 'Bet it continues' adds a flip without being counted. 'Auto-bet due ×500' places 500 'due' bets in one go, which pulls the win rate towards 50% much faster than single clicks.
The gambler's fallacy is the belief that a run of one result makes the other more likely next. In a 2004 study, people predicting random outcomes from a roulette game showed this 'negative recency', expecting the next result to break the recent pattern. Online rules assume the opposite: the UK Gambling Commission's RTS 7 does not permit 'compensated' games that shift probabilities during play, and says a simulated coin must land heads with probability 0.5 on every toss. Real roulette also differs from this coin: Pennsylvania's rules give a single-zero wheel 37 pockets with zero coloured green, so a red bet wins on 18 of them.
What it leaves out: The coin has no green zero, so it isolates independence rather than modelling a real wheel's edge, and the tally counts every bet against the latest flip, not only bets placed after long streaks. As an educational demo for readers aged 18 and over, it has no power to alter the edge of any real game.
Sources
Checked on 2026-11-05. Independent, not affiliated. 18+.
- UK Gambling Commission: Remote gambling and software technical standards, RTS 7: Generation of random outcomes (last updated 7 May 2024)gamblingcommission.gov.uk
- Ayton P, Fischer I. The hot hand fallacy and the gambler's fallacy: two faces of subjective randomness? Memory & Cognition 32(8):1369-1378 (2004), PubMed 15900930pubmed.ncbi.nlm.nih.gov
- Pennsylvania Code: 58 Pa. Code § 617a.1, Roulette ball; Roulette wheel and table; physical characteristics (current through 56 Pa.B. 6006, 5 September 2026)pacodeandbulletin.gov
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