How the free online coin flipper works

Each press produces one of two equally likely results: heads or tails. The outcome is chosen first with the browser's crypto.getRandomValues() function. The coin animation starts afterward and only reveals the result.

How we turn a random number into heads or tails

Create one empty 32-bit number. The browser creates a Uint32Array with space for one unsigned integer.
Ask the browser to fill it. crypto.getRandomValues() replaces the empty value with a cryptographically strong pseudorandom integer.
Use the full range. A 32-bit unsigned integer can be any whole number from 0 through 4,294,967,295.
Split the range exactly in half. Values below 2,147,483,648 are heads. Values at or above it are tails. Each side receives exactly 2,147,483,648 possible values.
Animate the chosen side. Only after the result exists do we spin the coin and show heads or tails.

The exact JavaScript used for each result

const randomValue = new Uint32Array(1);
crypto.getRandomValues(randomValue);

// 0x80000000 is 2,147,483,648: the exact midpoint.
const isHeads = randomValue[0] < 0x80000000;

Why this is the right approach

Balanced: the number range divides evenly, giving heads and tails the same number of possible values.
Stronger than Math.random(): the Web Crypto API is designed to provide cryptographically strong random values. Math.random() is used only to vary how many times the picture spins.
Private: the value is generated on your device. No question, choice, or result needs to be sent to our server.
Fast and widely supported: the browser provides the generator directly, with no third-party service or network request.

Browsers generally implement this with a cryptographically strong pseudorandom generator seeded from high-quality system entropy. We do not claim that it is a physical or quantum coin toss. It is the browser-standard method for strong random values. Read the technical references at MDN Web Docs and the W3C Web Cryptography specification.

When a coin toss is useful

This simple coin flip game works best when there are two acceptable options and you want a neutral tie-breaker. It can choose who goes first, split a task, settle a friendly disagreement, or demonstrate basic probability. For an important medical, legal, safety, or financial decision, do not leave the choice to chance.

Are heads and tails really 50/50?

In this simulator, yes: both outcomes are assigned the same share of the random-number range. Over a small number of flips, an uneven split is normal. The percentages tend to move closer to 50/50 only across many flips, and an exact tie is never guaranteed.

If you want to explore those odds, use the coin flip probability calculator. To run a larger experiment immediately, flip multiple coins at once.

Heads or tails: a simple way to decide

Assign one option to heads and the other to tails.
Press Flip Coin and wait for the result.
Use the outcome, or notice how you feel about it. Your reaction may reveal which option you preferred.

Frequently asked questions

Is the coin flip free?

Yes. You can flip the coin as often as you like without creating an account.

Does the site save my results?

Your totals are saved only in local storage in your browser so they remain available after a refresh. The reset button deletes those totals.

Can I flip the coin with a keyboard?

Yes. Press the space bar anywhere on the page, unless you are currently typing in a form field.

Why did I get several heads or tails in a row?

Streaks are a normal part of randomness. Every new flip still has the same 1-in-2 chance for either result, regardless of previous flips.

Flip a Coin

Choose the right kind of coin flip

Flip Multiple Coins

Coin Flip Probability