Scientists Toss 350,757 Coins and Prove Coin Tosses Aren’t 50/50 — Here’s the Actual Probability They Found

Have you ever played any game before and decided who should go first, based on a coin toss? This is probably because most people believe that flipping a coin has a 50/50 probability, with heads and tails having equal chances.

However, a new study set to prove that idea false found something surprising. By flipping 350,757 times, their results suggested that coin tosses are not exactly 50/50, and here’s the actual probability.

How Did Scientists Flip So Many Coins?

The scientists who did the study published at Cornell University gathered 48 volunteers from different countries. They used many sets of coins from 46 currencies, so one type of coin could not affect the result as much. Each person, all with unique flipping styles and powers, began doing coin tosses until collectively, they reached 350,757 tosses!

The volunteers flipped as many coins as they could for longer sessions, with some lasting several hours just doing coin tosses. That dedication made this study one of the largest studies on the actual results of a coin toss and not just its probabilities.

Read more: Cornell University

What Did the Study Find?

Scientists Just Proved Coin Tosses Are Flawed Using 350,757 Coin Flips

The study showed a surprising result: that coin tosses are not always 50/50, but more than that, a coin is more likely to land on the same side it started when flipped. About 50.8% of the time, their research showcases that if you start with heads, you are slightly more likely to end up with heads again, and vice versa.

But, we have to admit, this bias is very small, and the percentage is not that far from the expected 50%. However, the fact that they did it so many times, and the study’s scientific process was trustworthy, resulted in a credible probability of 50.6% to 50.9%, specifically around 50.8% for the side you started with.

Why Do Coins Bias Toward the Same Side?

This odd behavior and unexpected result are not from some type of magic; it is based on physics. Their findings could be explained by a phenomenon called precession, where the initial side that is facing above is more likely to spend a tiny bit more time on top in the air after the flip.

In other words, when you toss a coin, it spins in the air, wobbling between the front and back, called precession. The side facing downward, or the one you started with, is also more likely to be the one that lands because the other side will spend slightly more time facing upward if it began that way.

Read more: Phys.org

Why It Matters—Even A Tiny Bias Counts

What Researchers Learned from 350,757 Coin Flips

The idea that coin tosses are not always 50/50 came from a 2007 physics model by Persi Diaconis and his team, who predicted this same‑side bias would be around 51%. Although the new study did not reach 51%, it is a lot closer to it than 50%.

Both of these studies suggest that coins really do return to the same side more than half the time. Even though that difference is small and can’t be observed in everyday life, it is real, and the probability, in the way we do coin tosses, is not exactly 50/50.

Author's Final Thoughts

This is a study that highlights how important it is to test even familiar ideas with real data, where even a simple coin toss could reveal something that is not exactly obvious. By flipping 350,757 coins, scientists found that 50.8% of the time, the coin will land on the same side it started on. That bias might be tiny, but it is factual, and it demonstrates how the world and physics work in real time.

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