Coin Flip

About the Coin Flip

What is a coin flipper?

A coin flipper is a tool that tosses a virtual coin and shows heads or tails at 50% each.

It works like a real coin toss for settling a choice, and it also keeps a running tally. This coin flip draws each side with the Web Crypto API's crypto.getRandomValues() and rejection sampling, so heads and tails are exactly equally likely, and it can flip up to 10,000 coins at once.

What should you know before you flip a coin online?

• Heads and tails each have a 50% chance on every flip. The last flip has no effect on the next one.
• Streaks are more common than they feel. Five heads in a row comes up in 1 of every 32 runs of five flips, about 3.1% of the time.
• An even split is less likely than it sounds. Ten coins land exactly 5 heads and 5 tails only 24.61% of the time.
• A real coin isn't quite 50/50. A 2023 study of 350,757 flips found coins landed on the side they started on 50.8% of the time.

How do you flip a coin online?

1. Choose how many coins to flip. Pick 1 for a single toss, or any number up to 10,000.
2. Flip. Tap the coin, press the flip button, or press Space.
3. Read the result. It appears under the coin, with the tally, the longest streak and the recent flips.
4. Ask a yes or no question. Set Sides to Yes and No, and the same flip answers it.

Example

Ten coin flips will be converted to a heads and tails tally with the odds of that split:

10

6 heads, 4 tails
H T T H H T H H T H
Chance of exactly this split in 10 flips: 20.51%
Longest streak in this batch: 2

With 1 coin the result is Heads or Tails at 50% each, and with Sides set to Yes and No the same flip gives a yes or no answer.

Is a coin flip really 50/50?

A coin flip from a fair random number generator is exactly 50/50, and a real coin is very close.

A 2023 study led by František Bartoš recorded 350,757 flips and found that a coin lands on the side it started on 50.8% of the time. That matches a 2007 physics model by Persi Diaconis, Susan Holmes and Richard Montgomery, which predicted about 51%. When the starting side was random, heads and tails still came up 50/50.

This coin flipper has no starting side and no thumb. Each flip is a fresh draw from the browser's random number generator, so the split is 50/50 by design.

What are the odds of flipping heads several times in a row?

The chance of flipping heads several times in a row halves with every extra flip.

The same odds hold for tails. Getting either side every time, all heads or all tails, is twice as likely, so three matching flips come up 25% of the time.

Common mistakes

These coin flip mistakes come from trusting a gut feeling about chance.

• Expecting tails after a run of heads. Each flip is independent, so the next one is still 50/50. Believing otherwise is called the gambler's fallacy.
• Calling a coin biased after 6 heads in 10 flips. Small batches wobble, and 6 or more heads in 10 flips happens 37.7% of the time. Flip 1,000 coins and the share settles near half.
• Deciding what heads means after the flip. Agree which side wins before you flip, or the coin decides nothing.

Common Use Cases

People flip a coin when two options are equally good and someone has to choose.

• Settling a choice. Two restaurants that sound equally good, or who pays for dinner.
• Games and sports. Who kicks off or who serves first.
• Teaching probability. Flip 100 or 10,000 coins and watch the share of heads settle toward 50%.
• Yes or no questions. Switch Sides to Yes and No for a quick answer.

For more than two options, Spin the Wheel picks from a list. The Dice Roller rolls numbers, and the Yes or No Wheel spins for an answer.

Frequently Asked Questions

Is it always 50/50 when you flip a coin?

A coin flip from a fair random number generator is always 50/50, and a real coin is close. A 2023 study of 350,757 flips found a slight 50.8% lean toward the side the coin started on.

Is an online coin flip truly random?

Yes, this coin flip draws each side from crypto.getRandomValues(), the browser's cryptographic random number generator. Neither side comes up more often, and past flips have no effect on the next one.

What are the odds of flipping heads 5 times in a row?

The odds of a coin landing heads 5 times in a row are 1 in 32, or 3.125%. Each extra flip halves the chance, so 10 in a row is 1 in 1,024.

Can you flip a coin 100 times at once?

Yes, set the number of coins to 100, or anything up to 10,000, and press the flip button. The coin flip shows how many heads and tails came up and the chance of that exact split.

Which side of a coin is heads?

Heads is the side of a coin with the main portrait or emblem, usually a head of state. Tails is the other side.

How do you flip a coin on your phone?

Open the coin flip page in your phone's browser and tap the coin. The result appears under it, with no app to install.