Coin Flip Probability Calculator

Your details

How many times you toss the coin. Max 1,000 for real-time computation.
The target count of heads (or successes) you want to evaluate.
Choose whether you want the probability of getting exactly k heads, k or more heads, or k or fewer heads.
The probability of landing heads on a single flip. Use 0.5 for a fair coin, or a different value for a biased coin.
ProbabilityUncommon
0.205078

Exact binomial probability as a decimal (0 to 1)

Percentage chance20.5078%
Odds (1 in X)1 in 4.9
Expected heads5
Standard deviation1.581
0.205078
Very rare<0.01Rare0.01-0.1Uncommon0.1-0.5Likely0.5-0.9Very likely0.9+

20.51% chance of exactly 6 heads

  • The probability of getting exactly 6 heads in 10 flips of a fair coin (p = 0.5) is 20.51%.
  • On average you would expect 5.00 heads per 10 flips (n x p = 10 x 0.5).
  • About 68% of the time, the number of heads will fall between 3.4 and 6.6 (within one standard deviation of the mean).

Next stepFlip a physical coin or run a simulation to see how well actual results match this theoretical probability.

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