Coin Flip
The chance of a fair coin landing heads 10 times in a row is 1 in 1,024. In 3 flips, the chance of at least one head is 87.5%.
How to use
- Press Flip coin to get heads or tails. A single flip plays a short spin animation.
- To flip many times at once, choose 10, 100 or 1,000 first. The result shows how many heads and tails you got and the longest streak.
- Totals keep adding up across flips, so you can compare your running record with the 50 percent you would expect. Press Clear to start over.
How it works
Each flip asks your browser's cryptographic random generator for a number and maps it to heads or tails. Numbers that would favor one side are thrown away and redrawn, so both sides have exactly the same chance. No flip depends on an earlier one.
A streak is a run of the same side in a row. The longest streak is the longest run in your whole record, counted for heads and tails separately and then overall.
The percentages are your own counts divided by the total. They rarely sit exactly at 50 percent in a short run, and they drift closer to it as the number of flips grows.
Chance of a run of the same side
| Flips in a row | Chance of one specific side every time |
|---|---|
| 2 | 1 in 4 (25%) |
| 3 | 1 in 8 (12.5%) |
| 5 | 1 in 32 (about 3.1%) |
| 10 | 1 in 1,024 (about 0.1%) |
FAQ
Is the coin fair?
Yes. Each flip has a 50 percent chance of heads and 50 percent of tails, and the outcome is drawn from the browser's cryptographic random source rather than a simple formula such as Math.random.
Why do I see long streaks of heads or tails?
Random sequences contain more streaks than people expect. In 100 flips, a run of 5 or more of the same side is likely, and a run of 7 or more shows up in about half of all 100-flip sessions.
If I get five heads in a row, is tails more likely next?
No. Each flip is independent, so the next flip is still 50 percent heads and 50 percent tails. Believing otherwise is called the gambler's fallacy.
Can I use it to make a decision?
Yes, for low-stakes choices such as who goes first. Agree beforehand which side means which option, then flip once.
Is anything saved or sent?
No. Flips are made and counted in your browser and are gone when you leave the page.