Coin flipper | Make Decisions Instantly

Is a 50/50 Coin Flip Really Fair?

A fair coin has exactly two equally likely outcomes, so each flip is a 50/50 chance. This tool models that ideal coin: every flip reads a fresh random value from your browser's crypto.getRandomValues(), the same secure source used for cryptography, and maps it to heads or tails with no bias.

Real physical coins are very close to fair, but tiny imbalances in weight, the spin and the catch can shift the odds by a fraction of a percent. A digital flip removes those imperfections entirely, which is why it is ideal for teaching and for decisions that need to be demonstrably unbiased.

Over many flips the proportion of heads gets closer and closer to 50% — this is the law of large numbers. In a small number of flips, though, lopsided results and long streaks are completely normal: getting 7 heads in 10 flips is not "unfair", just chance.

How to Use

1. Tap the coin or press Flip for a single heads-or-tails result.
2. Optionally rename the sides (for example "Yes" and "No").
3. To run an experiment, enter a number and press Flip Many.
4. Watch the live tally of heads vs tails, percentages and longest streak.
5. Copy the results or clear them to start over.

Key Features

• Animated single coin flip with optional sound.
• Cryptographically secure randomness (crypto.getRandomValues) for a true 50/50.
• Flip up to 100,000 times at once for statistics demos.
• Live heads/tails counts, percentages and longest streak.
• Custom labels and copyable results in three formats.
• Mobile-first, works fully offline in your browser.

Common Use Cases

• Settling a quick yes/no decision fairly.
• Teaching probability and the law of large numbers.
• Choosing who goes first in a game.
• Generating random binary data for tests.
• Demonstrating coin-flip streaks and odds.