Streak Calc
Odds of win/loss streaks from win rate and length.
How to Use This Calculator
- Enter your single-bet win probability as a percentage (e.g., 55)
- Enter the streak length you want to test
- Enter the total number of bets
- Read off the streak probability and the 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 does my expected longest streak look so long?
Variance scales logarithmically with sample size. Across 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 or cold spells instead of plain variance.
How does streak length shape bankroll management?
Even a 60% win rate throws up 5+ losing streaks on the regular. Your bankroll management (Kelly fractions, flat staking) has to soak those up without busting. Run this calculator at a streak length of 5-7 to see how often those losing runs hit and size your unit to match.
Are sports streaks actually predictive?
Mostly not. Independent, coin-flip-style markets spit out streaks purely by chance. Small predictive effects exist (injury cascades, team morale) but they’re typically overhyped. Treat past streaks as variance unless you have concrete, model-based reasons to think otherwise.
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 that holds up well for large N and gives the typical longest streak you’d expect to see.