Work out coin toss instantly with clear inputs, formula shown and shareable results.
The streak probability is computed exactly with a dynamic programme that tracks the current run length and forbids it ever reaching the target, then takes one minus the survival probability. Runs are far more likely than intuition suggests: three heads in a row appears in about 83% of ten-toss sequences, which is why streaks are poor evidence of anything.
Run probability
P(at least one run of k) = 1 - P(never reaching a run of k), computed by tracking run length
All the same
P = p^n + (1 - p)^n
P(at least one run of k) = 1 - P(never reaching a run of k), computed by tracking run length. The streak probability is computed exactly with a dynamic programme that tracks the current run length and forbids it ever reaching the target, then takes one minus the survival probability.
Runs are far more likely than intuition suggests: three heads in a row appears in about 83% of ten-toss sequences, which is why streaks are poor evidence of anything.
Enter number of tosses, streak length you are asking about, chance of heads. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.