Is this coin flip truly random?

Yes. This coin flipper uses JavaScript's Math.random() function which provides a cryptographically sufficient pseudo-random number for each flip. Each flip has an independent 50/50 probability of landing heads or tails, just like a fair physical coin. The result of one flip does not affect the next.

What are the odds of flipping heads 10 times in a row?

The probability of flipping heads (or tails) 10 times in a row is (1/2)^10 = 1/1024, or approximately 0.098%. This is about 1 in 1,024. While rare, it will happen roughly once every 1,024 sequences of 10 flips. Each individual flip is still 50/50 regardless of what came before.

Why does my coin seem to land on heads more often?

With small numbers of flips, results can deviate significantly from 50/50. This is called short-run variance and is completely normal. Over hundreds or thousands of flips, the ratio will converge toward 50/50. This is an illustration of the Law of Large Numbers. Try flipping 100 or 1000 times using the multi-flip feature to see it in action.

Can I use this for making decisions?

Yes. A coin flip is a time-honoured method for making binary decisions. Some people find that the moment the coin is in the air, they realise which outcome they are hoping for, which helps clarify their actual preference. Either way, the result is genuinely random and fair.

What is the gambler's fallacy?

The gambler's fallacy is the mistaken belief that if heads has come up several times in a row, tails is now 'due'. In reality, each coin flip is independent. The coin has no memory. After 5 heads in a row, the next flip is still exactly 50/50. Past results do not influence future outcomes.

Coin Flipper

Flip a coin online for a fair, instant heads or tails. Use it to settle a disagreement, decide who goes first, break a tie, or make any quick 50/50 call without hunting for a real coin. Every flip is a genuinely random, independent result, and you can flip 10 or 100 coins at once to watch the law of large numbers pull the ratio back towards an even split. Your running tally of heads, tails, current streak, and percentages is tracked below, and you can press the spacebar to flip.

Heads

Total Flips

Heads

Tails

Current Streak

Flip history will appear here

About this coin flipper

This coin flipper generates a genuinely random result using JavaScript's Math.random() function. Each flip is independent, meaning the result of previous flips has no influence on the next one. The probability is exactly 50% heads and 50% tails on every single flip, just like a fair physical coin.

Probability reference

2 heads in a row: 25% (1 in 4)
5 heads in a row: 3.125% (1 in 32)
10 heads in a row: 0.098% (1 in 1,024)
20 heads in a row: 0.0001% (1 in 1,048,576)

The gambler's fallacy

It is tempting to think that after five heads in a row, tails is somehow "due". It is not. The coin has no memory, so the next flip is still exactly 50/50. This mistaken belief is called the gambler's fallacy, and the multi-flip feature above is a good way to see how short runs can look lopsided while the long-run average still settles near 50%.

Related tools

This coin flipper uses pseudo-random number generation. For cryptographic or security-critical applications, use a hardware random number generator.

If you've found a bug, or would like to contact us, or learn more about James Graham and Calculate.co.nz.

Calculate.co.nz is partnered with Interest.co.nz for New Zealand's highest quality calculators and financial analysis.

All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice.

Calculate.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform, helping Kiwis understand the home buying and selling process from start to finish. Whether you're a first home buyer navigating your first property purchase, an investor evaluating your next acquisition, or a homeowner planning to sell, Realtor.co.nz provides clear, independent, and trustworthy guidance on every step of the New Zealand property transaction journey.

Calculate.co.nz is also partnered with Health Based Building and Premium Homes to promote informed choices that lead to better long-term outcomes for Kiwi households.

Calculate.co.nz is hosted in Auckland via SiteHost new Zealand.

All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.