Streak Tool
Probability of winning or losing streaks from your win rate and streak length.
How to Use This Calculator
- Type in your single-bet win probability as a percentage (e.g., 55)
- Type in the streak length you want to test
- Type in the total number of bets
- Read off the streak probability and expected longest run
Formula
P(streak of N wins) = p ^ N
P(streak of N losses) = (1 − p) ^ N
Expected Longest Run (approx) = log(N · (1 − p)) / log(1 / p)
P(≥ 1 winning streak of length N in M bets) ≈ 1 − (1 − p^N)^(M − N + 1)
Frequently Asked Questions
Why is my expected longest streak so long?
Variance scales logarithmically with sample size. Over 1000 coin flips you’ll usually hit a run of 9-10 heads. Long streaks feel shocking but are mathematically expected — most bettors misread them as hot/cold spells instead of plain variance.
How does streak length affect bankroll management?
Even a 60% win rate throws off 5+ losing streaks routinely. Your bankroll plan (Kelly fractions, flat staking) has to ride these out without busting. Run a streak length of 5-7 here to gauge how often such losing runs hit, then size your unit to match.
Do sports streaks predict anything?
Mostly no. Independent events (coin-flip-style markets) generate streaks by pure chance. Small predictive effects exist (injury cascades, team morale) but tend to be overhyped. Treat past streaks as variance unless a concrete model gives you reason not to.
What's the math behind 'expected longest run'?
For independent Bernoulli trials with success probability p over N trials, the expected longest run of successes converges to log(N(1−p))/log(1/p). It’s a logarithmic approximation, accurate for large N, that yields the typical longest streak you’d see.