Streak Calculator

Calculate the probability of winning or losing streaks. Enter your win rate, streak length and number of bets to see streak odds and expected longest run.

Please enter a probability between 0.1% and 99.9%
Results
P(Winning Streak of Length N) --
P(Losing Streak of Length N) --
Expected Longest Run --
P(≥ 1 such streak in N bets) --

How to Use This Calculator

  1. Enter your single-bet win probability as a percentage (e.g., 55)
  2. Enter the streak length you want to evaluate
  3. Enter the total number of bets
  4. View 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 does my expected longest streak look so long?

Variance grows logarithmically with sample size. With 1000 coin flips you’ll typically see a streak of 9-10 heads. Long streaks feel surprising but are mathematically expected — most bettors mistake them for hot/cold periods rather than ordinary variance.

How does streak length affect bankroll management?

Even a 60% win rate produces 5+ losing streaks regularly. Bankroll management (Kelly fractions, flat staking) must absorb these without ruin. Use this calculator with a streak length of 5-7 to see how often you’ll see those losing runs and size your unit accordingly.

Are sports streaks predictive?

Mostly no. Independent events (coin-flip-like markets) produce 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 concrete model-based reasons to believe 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’s accurate for large N and gives the typical longest streak you’d observe.