Updated 18 October 2026
The basic rule
A fair coin has two equally likely outcomes, so each flip is a 1 in 2 chance (50%). Flips are independent: the coin does not remember what happened before. To get the chance of several specific results in a row, multiply: two heads in a row is ½ × ½ = ¼, three is ⅛, and so on, halving each time.
Odds of getting heads every time
If you flip a coin k times, this is the chance that every single flip is heads (the same applies to all tails):
| Flips | Odds all heads | Chance |
|---|---|---|
| 1 | 1 in 2 | 50.00% |
| 2 | 1 in 4 | 25.00% |
| 3 | 1 in 8 | 12.50% |
| 4 | 1 in 16 | 6.25% |
| 5 | 1 in 32 | 3.12% |
| 6 | 1 in 64 | 1.56% |
| 7 | 1 in 128 | 0.781% |
| 8 | 1 in 256 | 0.391% |
| 10 | 1 in 1,024 | 0.098% |
| 20 | 1 in 1,048,576 | 0.000% |
Notice that even the single most likely result, exactly half heads, gets less likely as you flip more. With 10 flips, exactly 5 heads happens about 24.6% of the time; with 100 flips, exactly 50 heads is only about 8%. What does get more reliable is the percentage: over thousands of flips, the share of heads settles close to 50%.
How common are streaks?
Most people underestimate streaks. Starting fresh, five heads in a row is a 1 in 32 shot, but in a long series of flips there are many places a streak can start, so long runs become very likely. This table shows the chance of seeing a run of heads of at least that length somewhere in the sequence:
| Streak | 10 flips | 20 flips | 50 flips | 100 flips | 1,000 flips |
|---|---|---|---|---|---|
| 3 in a row | 50.8% | 78.7% | 98.3% | 100.0% | >99.99% |
| 4 in a row | 24.5% | 47.8% | 82.7% | 97.3% | >99.99% |
| 5 in a row | 10.9% | 25.0% | 55.2% | 81.0% | >99.99% |
| 6 in a row | 4.7% | 12.2% | 31.5% | 54.6% | 100.0% |
| 7 in a row | 2.0% | 5.8% | 16.5% | 31.8% | 98.2% |
| 8 in a row | 0.78% | 2.7% | 8.4% | 17.0% | 86.1% |
| 10 in a row | 0.10% | 0.59% | 2.0% | 4.4% | 38.5% |
Counting a streak of either side (heads or tails) makes long runs more likely still. That is why a run of 6 or 7 the same in an afternoon of flipping is nothing to worry about.
The gambler's fallacy
After a long run of tails, it feels like heads is "due". It is not. The coin cannot see the history, so the next flip is still 50/50. The idea that results even out is true only in proportion: over many flips, an early streak becomes a smaller and smaller share of the total. The streak is diluted, not corrected.
Are real coin tosses fair?
Close, but not perfectly. In 2023, a team of researchers led by František Bartoš recorded 350,757 hand flips and found coins landed on the same face they started on around 50.8% of the time. The likely cause is that a tossed coin wobbles slightly, spending a little longer with its starting face up. Spinning a coin on its edge on a table is far less fair, because the weight of the design can tip it one way. A digital coin like ours has no starting face, so it avoids both problems.
Try it yourself
Use the coin flipper to flip 100 times and check your heads percentage and best streak against the table above. It is a great classroom experiment.
Frequently asked questions
What are the odds of getting heads 3 times in a row?
If you flip exactly 3 times, the chance that all 3 are heads is 1 in 8, or 12.5%. Each flip is a 1 in 2 chance, and 1/2 × 1/2 × 1/2 = 1/8.
What are the odds of 10 heads in a row?
Starting from scratch, 1 in 1,024 (about 0.1%). But over 1,000 flips there is roughly a 38% chance of a 10-heads streak appearing somewhere.
After 5 tails, is heads more likely?
No. A coin has no memory, so the next flip is still exactly 50/50. Expecting a 'due' result is the gambler's fallacy.
Is a coin toss fair in real life?
Almost. A 2023 study of 350,757 hand flips found coins landed on the side they started on about 50.8% of the time, a small but measurable bias. Spinning a coin on a table can be far less fair.