Flip a Coin 100 Times
Flipping a fair coin 100 times gives exactly 50 heads only about 8% of the time; 45 to 55 heads happens about 73% of the time.
Flip 100 times now
What's your call?
Practice · not recorded · no coins
Your results: heads, tails, longest streak
After you flip a coin 100 times, the results panel shows the number of heads, the number of tails and the longest streak of the same side. You can also see how your heads count compares with the expected 50, so you can tell at a glance whether the run was ordinary or unusual. Most runs look ordinary: 45 to 55 heads covers 72.87% of all results, and a streak of six or seven in a row is common. You can switch to 3, 10 or 1,000 flips and compare. Every batch is free and runs in your browser, with no sign up needed.
What's normal in 100 flips
A normal result for 100 flips is anywhere from about 40 to 60 heads, and most of the time it falls between 45 and 55. Exactly 50 heads happens only 7.96% of the time. 45 to 55 heads comes up 72.87% of the time, and 40 to 60 heads 96.48% of the time. Getting exactly 40, or exactly 60, is 1.08% each. So if your run ended with 53 heads and 47 tails, that is about as typical as it gets. Even 41 heads sits inside the range you would expect roughly 96 times out of 100. Only results outside 40 to 60 are genuinely rare.
Flip a coin 3 times: all outcomes
Flip a coin 3 times and there are 8 equally likely outcomes: HHH, HHT, HTH, THH, HTT, THT, TTH and TTT. Three heads in a row is one of them, so its chance is 1 in 8, or 12.5%. Exactly 2 heads shows up in three outcomes, which is 37.5%, and exactly 1 heads is also 37.5%. At least one heads happens 87.5% of the time. Set the flip counter to 3 to try it, then run it a few times and see how often you get HHH. If you are working on a probability question, the full binomial breakdown is on the coin flip probability page.
Streaks aren't suspicious
Streaks of six or seven in a row are completely normal in 100 coin flips. A run of at least 5 of the same side shows up 97.2% of the time, at least 6 shows up 80.7% of the time, and at least 7 shows up 54.2% of the time, so more often than not. A run of 8 or more appears 31.5% of the time, and 10 or more 8.7%. People expect randomness to switch sides a lot, so real streaks look suspicious, but a coin has no memory and does not try to balance out. If anything, 100 flips with no streak longer than four would be the odd result.
100 flips: what's normal
| Result | Chance |
|---|---|
| Exactly 50 heads | 7.96% |
| 45 to 55 heads | 72.87% |
| 40 to 60 heads | 96.48% |
| Exactly 40 (or exactly 60) heads | 1.08% |
Longest run somewhere in 100 flips
| A run of at least… | Chance |
|---|---|
| 5 | 97.2% |
| 6 | 80.7% |
| 7 | 54.2% |
| 8 | 31.5% |
| 10 | 8.7% |
FAQ
What is the probability of getting heads 3 times in a row?
It is 1 in 8, or 12.5%. Each flip is independent with a 1/2 chance, so three heads in a row is 1/2 × 1/2 × 1/2. When you flip a coin 3 times, the chance of exactly 2 heads is 37.5% and of at least one heads is 87.5%. Five heads in a row is 1 in 32, and ten in a row is 1 in 1,024.
What happens if you flip a coin 100 times?
You will usually get close to 50 heads, but rarely exactly 50. The chance of exactly 50 heads in 100 flips is about 8%. The chance of 45 to 55 heads is about 73%, and of 40 to 60 heads about 96%. Streaks are normal too: there is a 54% chance of seeing seven or more of the same side in a row somewhere in 100 flips.