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What Is A Coinbase Transaction In Bitcoin?

Last Updated December 19, 2023 12:18 PM
Andrew Kamsky
Last Updated December 19, 2023 12:18 PM

Key Takeaways

  • Coinbase transactions are always the first in a new block and initiate the creation and distribution of new cryptocurrencies.
  • These transactions distribute mining rewards through block subsidies and collect transaction fees, hence playing a vital role in the Bitcoin network.
  • Unlike regular transactions, coinbase transactions have no inputs, as they generate new Bitcoin, not transfer existing ones.
  • The halving process in Bitcoin periodically reduces mining rewards by half, directly affecting the rewards from coinbase transactions.

A crypto transaction involves an exchange of digital assets between two parties over a blockchain network. Each transfer is recorded as a data block and added to a public ledger on the cryptocurrencies respective blockchain, ensuring transparency and security. Each transfer can be identified on the blockchain explorer by inputting the public address.

Coinbase Transaction In Bitcoin, Explained

In every block, the first transaction, known as a coinbase or generation transaction, is crafted by a miner. Its primary function is to generate new coins. 

This transaction features a unique field called the coinbase, serving as its input. Additionally, it allows the inclusion of up to 100 bytes of arbitrary data, offering a space for storing various data types.

What Is The Genesis Coinbase Transaction?

In the early days of Bitcoin in 2009, Satoshi Nakamoto, while mining the very first genesis block, created the initial coinbase transaction. This transaction credited 50 BTC to the address ‘1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa’, aligning with the halving protocol of that period. 

Interestingly, the 50 BTC in this address remains unspent. 

Moreover, this genesis block is unique as it was never confirmed within the blockchain, a mystery that blockchain developers and researchers are left puzzled by. However, some suggest that this first coinbase transaction was hardwired into the genesis block’s source code, making the usual confirmation process unnecessary. This was likely done to avoid the creation of an alternate blockchain, which would result if the genesis block were left unconfirmed.

Demystifying Bitcoin Transactions: A Fundamental Process In Blockchain Value Transfer

In a Bitcoin transaction, the sender initiates a transfer of any Bitcoin amount, a process also applicable to other blockchains such as Ethereum, directing the transfer to the recipient’s digital wallet or public address. 

The transaction then undergoes verification by network participants, termed miners in proof-of-work systems and validators in proof-of-stake systems.

This secure and efficient method for value transfer in the digital era highlights the innovative mechanisms of blockchain technology. It introduces the unique concept offering called coinbase transactions, which play a pivotal role in creating and distributing new digital currencies.

Coinbase Transaction Basics

Coinbase transactions represent a unique aspect of the cryptocurrency network, distinct from regular payment transactions between two parties. Coinbase transactions involve creating and distributing new cryptocurrencies, similar to the minting of fiat currencies. 

Understanding the basics of a coinbase transaction is necessary for investors wishing to understand the cryptocurrency world, particularly individuals interested in mining and understanding blockchain technology. 

Purpose Of The Coinbase Transaction

A coinbase transaction’s primary role is to distribute the “block subsidy,” which is a reward for mining a new block, and to gather all the transaction fees from other transactions included in that block.

Crypto Mining Rewards: Block Subsidy And Fees

Currently, the crypto mining reward for finding a block offers miners a subsidy set at 6.25 BTC for each block. This implies that the miner who successfully adds a new block to the blockchain gets rewarded with 6.25 BTC. 

Additionally, the coinbase transaction includes all transaction fees from the block. Said fees are then paid by users who make transactions and want the transactions included in the blockchain.

Key Features Of Coinbase Transactions

Coinbase transactions exhibit distinct characteristics, setting them apart from regular cryptocurrency transactions. These characteristics or traits can be seen below:

No Inputs

Unlike regular transactions, a coinbase transaction doesn’t have any inputs. This is because it’s creating new Bitcoin as part of the block subsidy, not transferring existing ones.

Position In The Block

A coinbase transaction is typically the initial transaction in a new block, with the reward being directed to either a single wallet address or multiple addresses.

Restrictions On Spending Rewards

Rewards from a coinbase transaction require a certain number of confirmations before they can be spent. Rewards from a coinbase transaction in the Bitcoin network require 100 confirmations before they can be spent. 

The Concept Of Halving

The halving in the blockchain reduces the reward for mining a new block by half after a certain number of blocks are mined. In turn, this will affect the reward amount in each coinbase transaction.

Example Of A Coinbase Transaction

To understand the manner of Coinbase transactions better, one may look at a real example. For instance, in Block number 650,000  on the Blockstream Explorer, one may notice that the coinbase transaction has no inputs. 

This means that the transaction output is the sum of the block subsidy (6.25 BTC) and the transaction fees collected in that block, in this case, 0.244131 BTC. So, the total output of this particular coinbase transaction would be 6.494131 BTC.

Block #650,000
Block #650,000


Coinbase transactions are a cornerstone of the cryptocurrency world, underpinning the creation of new digital currencies and the reward system for miners. 

Coinbase transactions are unique in structure and serve a role in the blockchain that not only facilitates the cryptocurrency supply’s growth but also ensures the network’s ongoing security and robustness. 

Understanding coinbase transactions is required for anyone looking to deepen their knowledge of how cryptocurrencies function at a fundamental level.


What exactly is a coinbase transaction in Bitcoin?

A coinbase transaction, unique to each block in the blockchain, is the first transaction created by a miner. It’s important for generating new coins and includes a unique ‘coinbase’ field as its input. This transaction also allows for storing up to 100 bytes of arbitrary data.

How did the first coinbase transaction occur?

The first coinbase transaction was made by Satoshi Nakamoto in 2009 while mining Bitcoin’s genesis block. It involved transferring 50 BTC to a specific address, which remains a mystery as the blockchain never confirmed this transaction.

What are the characteristics of coinbase transactions?

Coinbase transactions are known for being the first in a block, requiring several confirmations before their rewards can be spent, and being affected by the halving process, which reduces mining rewards over time.

How do coinbase transactions differ from regular Bitcoin transactions?

Unlike standard Bitcoin transactions, Coinbase transactions are used to introduce new coins into the system and don’t have any inputs. They also play a role in distributing mining rewards and collecting transaction fees.

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