How to use it
- Choose how many coins to toss, from 1 to 10.
- Press Flip, or press Space or Enter.
- Check the running tally for heads and tails counts and percentages, and the history for each toss.
Settle it best of N
When one toss feels too final, switch to Best of N. In a best of 3, the first side to come up twice wins. Give heads and tails names such as "Pizza" and "Tacos" and the result shows those names. Best of N always tosses one coin at a time.
Good for
- Choosing between two options, like where to eat or what to watch
- Deciding who kicks off or picks a side before a game
- Probability lessons: toss 10 coins many times and watch the percentages settle
How the result is decided
Each coin is decided with a random number from your browser's crypto.getRandomValues. Instead of simply taking the remainder after dividing by 2, values from the uneven tail of the range are thrown away and drawn again (rejection sampling), so the remainder step adds no modulo bias. The result is fixed before the animation starts; the animation only shows it. If your device is set to reduce motion, the result appears without animation.
Is a real coin really 50/50?
Research suggests a hand-flipped coin lands on the side that started face up slightly more often. A 2007 physics model by Diaconis, Holmes and Montgomery predicted about 51%, and an experiment in which 48 people flipped coins 350,757 times (Bartoš et al., released in 2023) found the starting side about 50.8% of the time, while heads and tails overall came up 50.0% each. This tool does not use a starting side; the result comes only from the random number.