The confirmation risk calculator, created by the Software and Bitcoiner engineer Jameson LOPP, is introduced to the Bitcoin ecosystem (BTC) as a useful tool to understand the safety of transactions in that chain.
This development allows quantifying the level of certainty that a user can have when accepting a payment after a certain number of confirmations in the network. In an ecosystem where centralization of the mining and the computing power of the great pools generate questions about the robustness of the system, this calculator offers a technical and precise approach to Evaluate the risks of a double expense I am not bitcoin.
LOPP is a relevant figure in the bitcoiner ecosystem for its focus on individual security and sovereignty. Recently, for example, as Cryptonotics reported, he proposed an initiative to burn the BTC vulnerable to quantum computing, arguing that this measure would protect the integrity of the network against future technological threats.
What is the confirmation risk calculator and what is it for?
The LOPP calculator, presented for the first time in February 2023 in its personal blog, is a tool designed to assess the probability that a confirmed transaction in the Bitcoin Network be reversed by a double expense attack. This type of attack occurs when a malicious actor tries to rewrite the history of the block chain to cancel an already accepted transaction, spending the same funds on another operation.
The calculator based on a mathematical model that considers the percentage of hashrate (computing power) controlled by an attacker and the number of confirmations that the transaction has received, thus offering a risk calculation to which the payment receiver faces.
LOPP underlines its practical utility for merchants, exchanges and individual users who need to determine how many confirmations are enough before considering a definitive transaction.
LOPP was based on Bitcoin Whitepaper
Traditionally, says the engineer Bitcoiner, the empirical rule of waiting has been used Six confirmations to guarantee a security level of 99.99%assuming that the attacker controls 10% of the global hashrate.
However, LOPP argues that this assumption, established in Bitcoin protocol and reflected in the Satoshi Nakamoto Whitepaper, It is no longer held in the current panorama. «These calculations were made long before the invention of mining pools and industrial mining operations. At that time, it was reasonable to assume that it would be very difficult for someone to have more than 10% of the global hashrate,» writes LOPP, pointing out that since 2011 multiple entities have emerged with significantly higher participations.
At present, some mining pools, such as Foundry USA, Antpool, F2pool or Viaabtc, control among all 75% of the processing power contributed by Pools to the total of the Bitcoin network, according to Mempool.Space.
The technical model behind the calculator
The calculator is based on a probabilistic model described in pages 6 and 7 of Bitcoin Whitepaper, where competition is raised Between the honest chain and the attacker’s chain as a «binomial random walk.»
This mathematical concept describes a process in which each new block represents a step in a given direction: if the block is generated by the honest network (most hashrate), the advantage of this grows; If the attacker generates, his chain progresses and reduces the gap. Binomial nature comes from the fact that there are only two possible results per round, and the probabilities depend on the power of relative computing.
Lopp explains it as follows: «The player (attacker) is expected to lose most of the time, so the longer this game plays with a negative expected value, the less likely it is that it will be victorious.» Thus, with an attacker who has less than 50% of the hashrate, the probability that he can reach and overcome the honest chain decreases exponentially as the number of blocks to be overcome increases, a phenomenon that reflects the security inherent in Bitcoin’s design.
A concrete example that LOPP stands out in its analysis is the case of Foundry USA, one of the main mining pools that, at the time of the publication of the article (February 2023), controlled 36% of the global hashrate (32% currently). According to their calculations, if a user accepted a payment after only three confirmations, there was a 49% probability that Foundry I could rewrite the chain and execute a double expense.
Updating this analysis with data from March 2025, the relevance of the LOPP calculator becomes even more evident. Drawing the same equation, but with the current conditions of the network, if a user accepted today a payment after only three confirmations, the probability that Foundry USA can carry out that malicious behavior amounts to almost 52%.
This increase with respect to 49% calculated by LOPP in 2023, although Foundry now controls 32% of the hashrate, suggests that other factors (such as fluctuations in the total hashrate or greater potential coordination between Pools) could be influencing the risk. This data, integrated to the LOPP model, underlines how the Mining power concentration remains a critical variable In 2025, reinforcing the need for tools such as this to adjust security expectations to the reality of the network.
These calculations show how current mining dynamics have altered traditional security notions. For example, «the standard of six confirmations to reach 99.99% of certainty that a double expense will not occur (assuming an attacker with 10% hashrate) now requires 60 confirmations to achieve the same level of trust,» says LOPP.
Would a pool go against the Bitcoin Network?
The engineer also clarifies that this scenario does not imply an imminent or systemic threat to Bitcoin. The viability of such attacks is limited by practical and economic factors. The mining pools, LOPP details, are discouraged to perform this type of maneuvers, since a successful attack could undermine confidence in the network and, consequently, seriously affect your business.
Among the reasons for their confidence, it is highlighted that industrial miners deepen their search for cheap energy sources and distributed globally, as well as technological advances such as Stratum V2, which return some control to individual miners against Pools operators. In this sense, the role of Pool Ocean could also be highlighted, which uses its own Datum protocol, offering miners autonomy in their task.
The confirmation risk calculator remains a reflection of Bitcoin’s dynamism, a network that, despite its solid foundations, must adapt to the realities of modern mining. The data of 2025 confirm that the risks indicated by LOPP have not disappeared, but evolve over time, demanding users with a more precise understanding of security.