Streak Helper
See the chance of winning or losing streaks from your win rate and run length.
How to Use This Calculator
- Enter your single-bet win probability as a percentage (for example, 55)
- Enter the streak length you’d like to look at
- Enter the total number of bets
- View 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 come out so long?
Variance grows logarithmically as your sample gets bigger. Across 1000 coin flips you’ll typically spot a run of 9-10 heads. Long streaks feel surprising, but the maths expects them — most bettors mistake them for hot or cold spells when they’re really just ordinary variance.
How should streak length shape my bankroll management?
Even a 60% win rate throws up 5+ losing streaks on a regular basis. Your bankroll management (Kelly fractions, flat staking) needs to soak these up without busting you. Try this calculator with a streak length of 5-7 to see how often those losing runs turn up, then size your unit to match.
Are sports streaks actually predictive?
Mostly no. Independent events (coin-flip-style markets) throw up streaks purely by chance. There can be small predictive effects (injury cascades, team morale) but they’re usually overstated. Treat past streaks as variance unless you have solid, model-based reasons to think otherwise.
What's the maths behind the 'expected longest run'?
For independent Bernoulli trials with success probability p over N trials, the expected longest run of successes settles toward log(N(1−p))/log(1/p). It’s a logarithmic approximation that holds up well for large N and gives you the typical longest streak you’d expect to see.