Is there enough bitcoin for everyone?

Short answer: Yes.

There will only ever be 21 million bitcoin. But each bitcoin is made up of 100 million units called Satoshis (sats). So, we can do some math to figure out that twenty-one million bitcoin with 100 million sats each is 2.1 quadrillion pieces of bitcoin, more than enough for the almost 8 billion people on Earth— even if all the bitcoin hasn’t been mined yet, even if the world population keeps on growing.

Long answer: No.

Just because a bitcoin can be divided into 100 million sats doesn’t mean you can use a single sat by itself.

Bitcoin uses a blockchain. Think of this as an account book with pages full of entries. Every bitcoin transaction must be recorded in this book to be a real transaction. But there’s only so much room on each page, so every transaction pays a small fee for the space it takes up.

The fee is based on the size of the transaction in bytes. The fee is charged as a rate (sats per byte) and the cheapest rate is 1 sat per byte.

When you make a bitcoin transaction you have to include information about the piece or pieces of bitcoin you are using and information about where they are going.

Let’s imagine a transaction takes up 160 bytes, and you pay the minimum fee rate of 1 sat per byte. If the piece of bitcoin you are trying to transact is less than 160 sats, the fee to get it included in the blockchain will be greater than the amount of bitcoin it contains. It isn’t worth spending.

Currently, all implementations of the Bitcoin protocol include something called the Dust Limit. This is a minimum number of sats that must be spent in a transaction for the transaction to be broadcast to the network.

This dust limit is 546 sats, which means that transactions will not be relayed across the Bitcoin network unless the value of each piece of bitcoin coming out of the transaction is greater than 546 sats. This number is based on a multiple of the size of a very simple transaction.

At the moment, you can’t spend less than 546 sats. So there are not as many separate pieces of bitcoin as we thought.

However, the Dust Limit is a policy, not a rule of the Bitcoin protocol, and it could be changed (there was some discussion of this in 2021), but it’s not the only factor that controls how many people can use bitcoin.

Each block in the Bitcoin blockchain (each page of the account book) is limited in size, and can only contain around 2000 transactions (the number may be more or less, depending on the size of the transactions). The Bitcoin protocol also has a function that ensures that a new block is only added every 10 minutes, on average. This means that the average number of transactions that can be processed each day by the Bitcoin blockchain is about 300,000. At a world population of 8 billion, that’s not even 1 transaction per person each year.

Additionally, there are bitcoin that have been “lost” (owners have lost their keys and can no longer make a transaction with these pieces of bitcoin). Best guesses about how many bitcoin have been lost are between 3 and 4 million. So there aren’t even as many sats to begin with as we thought.

Altogether, this means that it is highly unlikely that each of the almost 8 billion people on Earth could use bitcoin.

Real answer: It doesn’t matter.

Lots of people say Bitcoin should increase the size of the blocks or the speed of the chain, or multiply the number of bitcoin that exist, or further divide them (instead of 100 million satoshis in each bitcoin, why not 100 billion?).

Even if all these changes were made, it still wouldn’t help 8 billion people to use bitcoin. This is because the real limiting factor for how many people can use bitcoin is actually something called the UTXO set.

The information about any piece of bitcoin you own is called an unspent transaction output (UTXO). A UTXO can be about a 10,000 bitcoin “piece” or it can be about a 1000 sat “piece.” Taken together, the information about all the different pieces of bitcoin that exist is called the UTXO set.

As the UTXO set gets bigger (as there are more UTXOs with smaller pieces of bitcoin in them) it becomes more difficult for average people around the world to verify every Bitcoin transaction entirely on their own computer (to run the math to make sure the spender really does own the bitcoin they are trying to spend).

If a large number of people from a wide array of places around the globe cannot verify the Bitcoin blockchain on their own — if they have to rely on a company, or a bank, or a government to do it for them — none of the 8 billion people on Earth will be able to use bitcoin, because it won’t be useful.

Bitcoin is a new kind of money: it can be sent to anyone, anywhere, anytime, and no one can take it from you. There will only ever be 21 million and no one is in charge of it.

But Bitcoin isn’t magical. It achieves these properties by being decentralized — because you don’t need special equipment to audit the blockchain, there are at least 50,000 people all over the world verifying every bitcoin transaction as you read this. If you need fancy equipment to audit the blockchain, that decentralization goes away, and you end up with money that a few groups control. It loses the anyone, anywhere, anytime properties that make it valuable.

So, how is bitcoin going to become money for the world?

There is no question that scalability is a major hurdle for Bitcoin adoption. Lots of people are working on solutions that allow more people to use bitcoin without sacrificing the properties that make it valuable.

Solutions like the Lightning Network have the potential to be used at a much greater scale. Lightning allows people to conduct a large number of transactions but only include two transactions on the Bitcoin blockchain. The beginning and end transactions, after everything in between is netted out, are all that take up blockspace. But the network is set up in such a way that it inherits most of the valuable properties of bitcoin itself.

Solutions like this are called layer 2 solutions. Layer 1 is the blockchain, which doesn’t scale very well at all, but provides the strong censorship resistance and decentralization that makes the money valuable. Layer 2s are whatever systems people dream up for using transactions on the blockchain to facilitate transactions that are not included on the blockchain.

So, will people pay for dinner with a transaction on the bitcoin blockchain in the future? No, but the payment system they use will likely be built on a foundation layer of bitcoin. There are a number of different layer 2 projects like Lightning that have the potential to dramatically increase the number of people who can use bitcoin. It is just going to take a little while for creative minds to figure out how to make them work. In the meantime, maybe you should get some bitcoin for yourself, just in case it catches on.

Thanks to John Carvalho and Marty Bent for reminding me of this issue. These thoughts aren’t new; lots of bitcoiners have been talking about the problem for a long time. But it’s hard to find much maintstream discussion of the issue these days, especially aimed at normal bitcoiners (not devs). So I thought I’d add the above to the conversation to keep the topic in the spotlight.