Comprehensive Calculator Guide
This calculator gives the exact chance of a run of k or more heads somewhere in n flips, and of a run of either face. Six heads in a row within 100 flips happens about 54.6% of the time. That is far more often than most people expect.
Streaks are common
One start point gives p^k, but many start points add up. Real random sequences are full of runs; invented ones avoid them.
How to Use
- Enter the flips and the run length.
- Change p if needed.
- Press “Calculate” to see the chances.
Formula Used
One start: p^k | Overall: tracked flip by flip
Practical Examples
- Example 1
- 6 in 100: 54.61%, either face 80.68%.
- Example 2
- 3 in 10: 50.78%.
Important Tips
- A long run isn’t proof of bias.
- Try the real-vs-fake classroom test.
- Works for any two-outcome series.
Common Mistakes to Avoid
- Using the single-start chance.
- Expecting a reversal.
- Mixing heads-only and either-face runs.
Frequently Asked Questions
- 10 heads in a row?
- About 0.1% at one start.
- Longest run in 100?
- Usually 5–6.
- Does a run mean bias?
- Not necessarily.