What is blockchain transaction fee?

Transaction fees serve two essential purposes when it comes to blockchain networks. They reward miners or validators who help confirm transactions and help protect the network from spam attacks.

Transaction fees can be both small or large, depending on the network activity. Market forces can also influence the fees you pay. While high fees can hinder wider blockchain adoption, very low fees could potentially bring security concerns.

Why transaction fees?
Transaction fees are and have been an essential part of most blockchain systems since their inception. You are most likely to have come across them when sending, depositing, or withdrawing crypto.

The majority of cryptocurrencies use transaction fees for two important reasons. First of all, fees reduce the amount of spam on the network. It also makes large-scale spam attacks costly and expensive to implement. Secondly, transaction fees act as an incentive for users that help verify and validate transactions. Think of it as a reward for helping the network.

For most blockchains, transaction fees are reasonably cheap, but they can get quite expensive depending on network traffic. As a user, the amount you choose to pay in fees determines your transaction's priority in being added to the next block. The higher the fee paid, the quicker the confirmation process.

Bitcoin transaction fees
As the world's first blockchain network, Bitcoin set the standard for transaction fees used by many cryptocurrencies today. Satoshi Nakamoto realized that transaction fees could protect the network from large-scale spam attacks and incentivize good behavior.

Bitcoin miners receive transaction fees as part of the process of confirming transactions to a new block. The pool of unconfirmed transactions is called the memory pool (or mempool). Naturally, miners will prioritize transactions with higher fees, which users agreed to pay when sending their BTC to another bitcoin wallet.

Malicious actors who wish to slow down the network must therefore pay a fee associated with each transaction. If they set the fee too low, miners will likely ignore their transactions. If they put them at a suitable level, they incur a high economic cost. So, transaction fees also act as a simple but effective spam filter.

How are BTC transaction fees calculated?
On the Bitcoin network, certain crypto wallets allow users to set their transaction fees manually. It's also possible to send BTC with zero fees, but miners will most likely ignore such transactions, meaning they won't be validated.

Unlike some tend to believe, Bitcoin fees are not dependent on the amount sent but on the transaction size (in bytes). For example, imagine your transaction size is 400 bytes, and the average transaction fee is now at 80 satoshis per byte. In that case, you would have to pay around 32,000 satoshis (or 0.00032 BTC) for a good chance of having your transaction added to the next block.

When network traffic is high, and there is a great demand for sending BTC, the transaction fee needed for speedy confirmation rises as other bitcoin users try to do the same. This may occur during periods of intense market volatility.

As such, the high fees can make it challenging to use BTC in day-to-day situations. Buying a $3 cup of coffee might not be practical if the fees are much higher than that.

Only a certain number of transactions can be included within a block, which has a limit of 1MB (i.e., block size). Miners add these blocks to the blockchain as quickly as possible, but there is still a limit to how fast they can go.