Bitcoin transaction/sec calculation

You might have heard in news, websites, word of mouth or any other communication channel that the bitcoin transaction rate is somewhere between 3 to 7 transactions/sec.

If you are like me, you want to understand where this number come from or how it is calculated. So here it is. Before I get to the calculation, we need to define few terms and they are:

Transaction — is a transfer of bitcoin from one address to another. Example, John transferring bitcoin to Smith inorder to buy bitcoin ebook.

Block — a group of transactions, marked with a timestamp and fingerprint of the previous block.

Block chain — is a list of validated blocks, each linked to its predecessor all the way to the genesis block.

If you want to remember them easily, just think of them as train, carriage & passengers. Transactions is your passengers, carriage contain passengers (in this case it is block) and train consists of series of connected carriages (in this case it is blockchain).

Now that we have defined the terms, lets get to the calculation.

source: https://tradeblock.com/bitcoin/historical/1w-f-tsize_per_avg-11101-blksize_per_avg-01071

From the above graph we can see that the block size is getting to 1MB and average transaction size is hovering around 505bytes. So…

How many transactions/block?

Formula: Transactions/block = Block size/average transaction size.

Average transactions/block = 1000000 Bytes/505 Bytes => 1980

What is the transactions/sec?

Formula: Transactions/sec = Transactions per block/ block time (in seconds)

Note: A new bitcoin block is on average discovered every 10 minutes. Therefore,

Transactions/sec = 1980/(10*60) = 1980/600 = 3.3

There you have it, now you know how the transaction/sec value for bitcoin is calculated.