Coin Toss Streak Calculator

Calculate the probability of consecutive heads or tails in coin flip sequences

Calculate Streak Probability

Total number of coin tosses (1-100)

Number of consecutive heads/tails

Type of streak probability to calculate

Display format for probability

Streak Probability Results

26.2695%
Exactly 3
50.7813%
At least 3
75.4883%
At most 3

Selected Result

Probability of exactly 3 consecutive heads in 10 flips:26.2695%

Mathematical Calculation

Formula used: P(L ≤ k) = f(k,n) / 2^n

Recurrence relation: f(k,n) = Σ f(k, n-i) for i = 1 to k+1

Total possible outcomes: 2^10 = 1,024

Sequence type: 4-step Fibonacci (Tetranacci)

Probability Interpretation

🎲 Moderate probability event - this streak has a reasonable chance
Expected frequency: About 26 times out of 100 sequences

4-step Fibonacci Sequence

The f(k,n) values used in calculating streak probabilities follow a 4-step Fibonacci pattern:

f(3,0)
1
f(3,1)
2
f(3,2)
4
f(3,3)
8
f(3,4)
15
f(3,5)
29
f(3,6)
56
f(3,7)
108
f(3,8)
208
f(3,9)
401
f(3,10)
773

Example: 3 Heads in 10 Flips

Problem Setup

Question: What's the probability of getting at least 3 consecutive heads in 10 coin flips?

Method: Use f(k,n) recurrence relation

Solution

P(L ≥ 3) = 1 - P(L ≤ 2)

P(L ≤ 2) = f(2,10) / 2^10

f(2,10) = 504 (Tribonacci sequence)

Result: ≈ 50.78%

Fibonacci Sequences

2-step (k=1):Fibonacci
3-step (k=2):Tribonacci
4-step (k=3):Tetranacci
5-step (k=4):Pentanacci

Statistical Tips

Longer streaks become exponentially less likely

Order matters: HHHTT ≠ HTHTH despite same totals

At-least probabilities are always ≥ exact probabilities

More flips increase chances of longer streaks

Understanding Coin Flip Streak Probabilities

What Are Streaks in Coin Flips?

A streak (or run) occurs when you get the same result several times in a row. Unlike basic coin flip probability where only the total count matters, streak analysis considers the order of results. For example, HHHTH has a streak of 3 heads, while HHTHH has only a streak of 2 heads.

Why Study Streaks?

  • Understanding randomness and probability patterns
  • Applications in gambling and game theory
  • Quality control and statistical process control
  • Financial market analysis and trend detection

Mathematical Framework

P(L ≤ k) = f(k,n) / 2^n

f(k,n) = Σ f(k, n-i) for i = 1 to k+1

  • L: Length of longest head streak
  • k: Target streak length
  • n: Total number of coin flips
  • f(k,n): Number of sequences with max streak ≤ k

Key Insight: The f(k,n) values follow generalized Fibonacci sequences, making this problem connect to famous mathematical sequences!

Probability Types Explained

Exactly k

The probability that the longest streak is exactly k heads in a row. Calculated as P(L ≤ k) - P(L ≤ k-1).

At Least k

The probability of getting k or more consecutive heads. Calculated as 1 - P(L ≤ k-1).

At Most k

The probability that the longest streak is k heads or fewer. Directly calculated as P(L ≤ k) = f(k,n) / 2^n.