Author: b10c, Bitcoin developer; Compiled by: AIMan@Golden Finance

This article discusses the centralization of Bitcoin mining in 2025 by analyzing the computing power share of the current five major mining pools. A mining centralized index is proposed in the article and updated using AntPool and its friends' proxy mining pool. The index shows that Bitcoin mining is currently highly centralized, and six mining pools have mined more than 95% of the blocks.

In the current Bitcoin mining landscape, almost all computing power is controlled by a few large mining pools, which are responsible for generating block templates. These pools control which transactions are included in their blocks and which are excluded. As long as these mining pools do not collude and decide to review transactions, this will not damage Bitcoin's censorship resistance. However, this also begs the question: how many different block template producers are there? The well-known 51% attack refers to a single miner or mining pool controlling more than half of the computing power and can surpass all other miners by mining on their own chains. However, even if a mining pool has only 40% computing power, there is a roughly 50% chance of outperforming all other mining pools in six blocks. What mining pools nowadays have 40% computing power? Overall, how centralized is Bitcoin mining today? Especially in the case of a hypothetical proxy mining pool, smaller mining pools represent mining tasks for larger mining pools while writing their own name into coinbase transactions.

This article discusses the issue of centralized Bitcoin mining in two parts. The first part analyzes the mining pool information contained in the Coinbase transaction. The second part considers the hypothetical proxy pool. Both parts showcase the largest mining pool and mining centralized index.

The pool usually leaves the ASCII tag in its coinbase transactions. For example, the mining pool F2Pool contains the tag /F2Pool/. Additionally, mining pools often reuse their coinbase output addresses. The data set of these identifiers can be used to find which mining pool mined blocks. In this article, I used the bitcoin-data/mining-pools dataset. In order to measure the proportion of computing power, I calculated the daily block count of each mining pool divided by the total daily block count. The data displayed are averaged using a 31-day moving average.

The computing power of the top five mining pools is currently Foundry (30%), AntPool (19%), ViaBTC (14.5%), F2Pool (10%) and MARA Pool (5%). Among them, MARA Pool is the youngest mining pool and was established in May 2021. In addition, it is also the only private mine in the top fivePool. At the end of 2020, Foundry began digging out the first batch of blocks. After one year of operation, Foundry surpassed other mining pools and became the largest mining pool, accounting for about 17% of the computing power of the entire network. More than a year later, in January 2023, Foundry's computing power accounted for 30% of the coins and has remained at this level. The computing power of AntPool, a mining pool owned by ASIC mining machine maker Bitmain, rose from around 10% in 2020 to more than 25% in 2024, and then dropped to below 20% again by the end of 2024. Last year, ViaBTC surpassed F2Pool in the competition for third place.

At present, the two largest mining pools account for more than 50% of the computing power, followed by third and fourth places, which together account for 25%, which means that 75% of the computing power is controlled by four mining pools. To better understand this, the following mining centralized index can help.

Mining Centralized Index

In order to measure the change in the degree of Bitcoin mining centralization over time, the Mining Centralized Index displays the sum of computing power of the top 2, top 3, top 4, top 5 and top 6 mining pools. The higher the value, the higher the degree of centralization.

For example, in May 2017, the total computing power of the top two mining pools was less than 30%, and the total computing power of the top six mining pools was less than 65%. At that time, Bitcoin mining reached the most decentralized level in the history of mining pool mining. The situation in December 2023 is in sharp contrast to this, when the top two mining pools controlled more than 55% of the computing power, while the top six mining pools controlled 90% of the computing power. Compared with the period from 2019 to 2022, the top two mining pools controlled about 35% of the computing power of the entire network, while the top six mining pools controlled about 75% of the computing power. In comparison, the current centralization of Bitcoin mining is much higher.

It is observed that AntPool and multiple smaller mining pools emit very similar block templates. It is presumed that these smaller pools are proxy pools for AntPool, meaning that they relay the mining jobs for AntPool but change the coinbase tag and address to their own. This causes the computing power estimation based on coinbase tags and addresses to become inaccurate. Since the block belongs to smaller miners, AntPool's computing power share is underestimated. However, AntPool and these smaller miners (collectively, "AntPool & Friends") can be counted as a large mining pool consisting of multiple mining pools. It can only be assumed which mining pools fall into the "AntPool & Friends" category and it is unclear when they areJoin this group. As of this writing, the following mining pools are considered part of the AntPool & friends group: AntPool, Poolin, CloverPool, Braiins, Ultimus Pool, Binance Pool, SecPool, SigmaPool, Rawpool, Luxor, Mining Squared. Since there is no sufficient evidence yet, SpiderPool is not currently considered an AntPool proxy.

The proportion of computing power of "AntPool and its friends"

This chart assumes that all mining pools considered "AntPool and its friends" belong to the alliance since 2023. Since this assumption has not been confirmed, it is assumed that the computing power share for the whole year of 2023 is slightly overestimated. However, the data for 2024 should be more accurate, with "AntPool and its friends" accounting for about 40% of the computing power of the entire network. While AntPool and its friends have higher computing share than Foundry in the past two years, Foundry appears to have grown 5% in early 2025, while AntPool and its friends have dropped by 5%. This trend seems to be reversing as AntPool and his friends grow again.

Given that AntPool and his friends share of computing power is 10% to 15% higher than what was assumed in the previous Mining Centralized Index chart, it is worth a reexamination of the index.

Considering "AntPool and its friends" Mining centralized index

The mining centralized index containing AntPool and its friends shows that in the past two years, "AntPool and its friends" and Foundry have controlled 60% to 70% of the computing power. What's worse, however, is that 96% to 99% of blocks are mined by only six mining pools. These data suggest that Bitcoin mining is highly concentrated in a few mining pools with production templates.

Bitcoin requires a small mining pool like MARA Pool with a 5% computing power. Some large American mining companies may leave Foundry and start mining independently with their computing power. In addition, transferring computing power to mining pools like Ocean (<1%) or DEMAND (0%) allows miners to build mining templates on their own, which helps to increase the degree of decentralization of Bitcoin mining. More individuals and small miners are also helpful in mining at home, however, the computing power of home mining is still insignificant compared to industrial computing power.

How many different block template manufacturers are there?

IWe can't tell, but we know that six block template producers mine more than 95% of the blocks.

Are there currently a mining pool with 40% computing power?

No, but it is estimated that AntPool and his friends control about 40% of the network’s computing power in 2023 and throughout the first half of 2024. Foundry has about 35% of its computing power in early 2025. Currently, AntPool and Foundry each have more than 30% of their computing power.

How is the centralization of Bitcoin mining today?

Based on the mining centralization index, Bitcoin mining briefly reached its most decentralized state in May 2017. It was also a good period from 2019 to 2022. Starting in 2023, Bitcoin mining has become increasingly centralized, especially driven by large mining pools such as Foundry and proxy mining pools such as AntPool.