How much would it cost to store the Bitcoin Cash blockchain?

There has been a lot of discussions about how large the blockchain of a cryptocurrency like Bitcoin Cash could grow if became a mainstream currency. Let’s test it with some hypothetical estimates and current data to see how far it is possible to grow.

The blockchain stores transactions in the form of bytes. A transaction requires on average between 250 and 500 bytes (or even more), depending on its complexity, the number of inputs and outpust. For comparison, a single tweet can store up to 280 B (280 ASCII characters).

To calculate the current capacity of the network, we can take the maximum block size (32 MB) and divide it by the average size of a transaction (350 B). This gives us that the number of transactions per block is (this number may vary):

32 MB / 350 B/tx ≈ 91 400 tx

Since the average time between blocks is 10 minutes, with 32 MB we would reach up to approximately 150 tx/s. This is still higher than the current capacity of the BTC network (up to 7 tx/s), but still not enough for the overall demand for digital transactions.

Suppose then that we increase the maximum block size to 10 GB. Per block there would be up to:

10 GB / 350 B/tx ≈ 28 500 000 tx (!)

In transactions per second:

28 500 000 tx / 10 min ≈ 47 500 tx/s

This is ten times what Visa, Mastercard, Paypal, etc. process. But is it possible to have such huge blocks? Would the network and storage be enough? Let’s go one at a time. As for bandwidth:

10 GB / 10 min ≈ 130 Mb/s

There are domestic connections that reach 1 Gb/s and corporate connections that can reach up to 10 Gb/s. There is almost no current restriction with bandwitdth.

On the other hand, storage space seems to be more concerning. Ignoring pruning (section 7 of the Bitcoin whitepaper), blocks of 10 GB every ten minutes yield the following space requirement:

10 GB / 10 min = 525.96 TB / year

“But that’s too much! There would be no nodes or miners who could pay that much for that much storage space!”

Let’s do some market research, at today’s price, on how much it would cost to store up to 600 TB of data per year. On Amazon, a 16 TB drive designed to store data on a server costs $350. To store 600 TB, 38 drives are required, i.e. an investment of 13,300 USD.

Does it still seem too much? Let’s see what an ASIC, which is the only type of machine capable of mining Bitcoin Cash profitably, costs: almost 20,000 USD per unit!

The largest mining farm in the United States has 100,000 ASICs. You do the math.

In other words, for just over half the cost of a single top-of-the-line ASIC, we can store transactions for a huge number of people.

It turns out that the blockchain scales very well. In the end, Satoshi was right.