Bitcoin wins users nonstop, but how far can it support its infrastructure? Can it support millions of users? How far is the Bitcoin scalability?

Paradoxically, the sudden arrival of millions of users delighted by its advantages would not benefit them, indeed, it could harm them a lot, since the experience of all users would be seriously affected.

And it is not unknown. One of the frequently asked questions about Bitcoin is: can it work if millions of people decide to make it their main means of payment?

Unfortunately, with the current version of Bitcoin, the answer is no.

However, this problem has its days numbered, as it has been the obsession of many programmers who have created multiple incredible scalability proposals. Now it only remains to decide, through consensus of the nodes., which and when it will be implemented.

In the next chapter we will help you understand, even more, the guts of Bitcoin and why it is currently not scalable, while we will accompany you to learn about some of the most notable scalability proposals.

Bitcoin and scalability: Bitcoin is currently not scalable

Let's first emphasize that by scalability we do not mean that Bitcoin cannot be understood by the majority of the population due to the paradigm shift as money. Nor because, due to the price that it can reach, it is inaccessible for some people. Nor that there could not be enough bitcoins for everyone.

All of this, apart from being false, is not what we are referring to when talking about scalability.

As of today, November 2016, Bitcoin is not perfect:

  • Payments are not instantaneous (although they are reflected instantly, they are not confirmed instantly).
  • Micropayments are becoming totally unfeasible. One of the great features of Bitcoin.
  • There is a constant risk of high mining centralization.
  • Bitcoin is not scalable.

As we can see, there is much to improve (or as some see it: opportunities to create great things) but, of all the issues to be solved in Bitcoin, the last one we have mentioned is one of the main tasks to achieve: that Bitcoin be scalable. Fixing this will make the other problems mentioned cascade better.

Bitcoin aspires to be a global financial system, and the data shows that people are in favor of it, so it must be prepared for its use by million concurrent usersAnd all this without losing any of its main characteristics that make it truly unique and valuable.

And is that Bitcoin is still an experiment. An incredible and popular experiment, yes, but one that is still at an early stage. In fact, despite having revolutionized the entire financial sector from its most archaic pillars (and other sectors as well), version 1.0 of the software has not even come out, we are still in version 0.20.1 (released in August 2020).

This means that we are still in a moment of constant development to be able to create the software with enough power to be used massively and in an optimal way.

In fact, its scalability problem is a debate almost as old as Bitcoin itself and the main reason for it is very localized: the block.

The block

As we already explained in the chapter dedicated to blockchain, blocks are the essential piece of the blockchain, which is the distributed ledger that supports Bitcoin.

The blocks store the essential information regarding all the transactions that occur. The problem is that each block is limited to the maximum size of information it can store.

En How do Bitcoin transactions work?? We explained that a block stores all the transactions that have occurred since the last block. Each of these transactions is made up of a series of information, which occupies a variable amount of disk space and which will be added to the block.

As a temporary measure to prevent network attacks (we'll see why below), and until we find better solutions, Satoshi Nakamoto decided to add an extra line of code to limit the capacity of each block in 1 Megabyte (Despite the fact that initially no limit was set or the miners later agreed not to accept blocks greater than 500kb). A size, which in its time, was more than enough.

Which means that each node of the Bitcoin network has the Bitcoin program running, which has written in its source code that no block can occupy a disk space greater than that indicated, and if it exceeds it, it must be rejected.

And here is the key, the size, as this determines the capacity of Bitcoin. Let's see why.

Filling the block

A normal transaction in Bitcoin usually occupies between 0.2kb and 1kb within the block (although there are some that occupy more, the normal thing is this).

With this data we will take 0.5kb (which is a fairly common size) as the average size per transaction. If we also take into account that the maximum size of the block that is created every 10 minutes is 1024kb (1mb),