Coin Flip Probability
Calculate the exact odds of any coin flip sequence. Heads or tails — what are the chances of your next streak?
Probability0.0977%
Odds1 : 1,024
Stop calculating. Start flipping.
Start FlippingProbability Table
Every coin flip is independent. The probability of a sequence is simply 0.5 raised to the power of the streak length. Use the calculator above or reference the table below.
| Streak length | Probability | Odds |
|---|---|---|
| 1 | 50.0% | 1 : 2 |
| 2 | 25.0% | 1 : 4 |
| 3 | 12.5% | 1 : 8 |
| 5 | 3.1% | 1 : 32 |
| 7 | 0.7813% | 1 : 128 |
| 10 | 0.0977% | 1 : 1,024 |
| 15 | 0.003052% | 1 : 32,768 |
| 20 | 1 in 1 million | 1 : 1 million |
| 25 | 1 in 33.6 million | 1 : 33.6 million |
| 30 | 1 in 1.1 billion | 1 : 1.1 billion |
| 40 | 1 in 1 trillion | 1 : 1 trillion |
| 50 | 1 in 1 quadrillion | 1 : 1 quadrillion |
Why Streaks Are Rarer Than You Think
Humans consistently underestimate how rare long streaks are. A 10-streak has less than 0.1% probability, yet many people think it should happen "eventually." The fact is: most players will never reach 10 in a row. The current world record is 21 — see the leaderboard.
