Streak Calculator
Probability of win or loss streaks given your strike rate and run length.
How to Use This Calculator
- Input your single-bet win probability as a percentage (e.g., 55)
- Input the streak length you want to assess
- Input 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 is my expected longest streak so long?
Variance scales logarithmically with sample size. Across 1000 coin flips you’ll typically observe a run of 9-10 heads. Long streaks feel startling but are mathematically expected — most bettors misread them as hot/cold periods rather than routine variance.
How does streak length feed into bankroll management?
Even a 60% win rate generates 5+ losing streaks on a regular basis. Bankroll management (Kelly fractions, flat staking) has to absorb these without ruin. Run this calculator at a streak length of 5-7 to see how frequently those losing runs occur and size your unit accordingly.
Do sports streaks have predictive power?
Largely no. Independent events (coin-flip-like markets) generate streaks purely by chance. Minor predictive effects exist (injury cascades, team morale) but are usually overstated. Treat past streaks as variance unless you hold concrete model-based reasons to think otherwise.
What's the math driving '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 returns the typical longest streak you would observe.