On April 2, 2025, a curious fact caught the attention of Bitcoin network observers. As reported by X user and mempool developer @mononautical, Foundry USA, one of the largest mining pools in the ecosystem, mined a block with just seven transactions,the emptiest block in over two years, according to the Mempool.space developer.
Analyzing the data of the block in question through mempool.space, it was observed that it was mined on April 1, 2025. Its size was 1.94 bytes, with a total weight of 5,369 WU (weight units).
The block included only 7 transactions. Source: Mempool.space
The block included only 7 transactions. The block did not generate any fee revenue, as the fee rate ranged from 0 to 5 satoshis per vbyte, and the median fee was 0 satoshis per vbyte.
In total, the fees collected were 0.00 BTC; in USD, it raised approximately $5.91, showing exceptionally low total fees when other blocks reach up to $4,000 in fees.
Meanwhile, the subsidy for mining the block was 3.125 BTC, which corresponds to the current normal reward after the last halving in 2024. This subsidy, added to the non-existent commissions, gave Foundry USA a total income of 3.125 BTC, equivalent to $266,247 at the time of mining.
According to mempool data, block 890466 raised -70%, -81%, and -84% of the expected fees, weight, and transactions. Foundry USA is a key player in Bitcoin mining. Founded in 2020 and based in the United States, the company has become the pool with the highest hashrate in the world.
This block of seven transactions comes in a particular context for the Bitcoin network, which has been showing a trend of low-activity blocks in recent days.
Several miners, including pools like F2Pool and AntPool, have also been mining blocks with a small number of transactions. This situation appears to be related to the mempool (the "waiting room" for pending transactions) being practically empty, limiting the number of transactions available to include in blocks.
The Foundry block, with its seven transactions, aligns with this trend but is notable for being the emptiest in over two years, according to Mempool.space, suggesting the network is experiencing a period of low transaction activity.
However, the reason why this block mined by Foundry has so few transactions could be explained, in addition to the low activity on the network, by something even more essential: the timestamps of Bitcoin blocks.
As is universally known, the average processing time for each block in Bitcoin is 10 minutes. However, due to the probabilistic nature of this blockchain accounting process, these times can be longer or shorter.
The latter is precisely what can be seen at block 890466 in the mempool. The block was mined just one second after block 890465 (at 20:38:17), according to the timestamps, which are measured in UTC. This means that the block with only 7 transactions wouldn't have had enough time to be filled with user transactions, hence the unusually low number of them.
Of course, if more users were using the Bitcoin network at the present time, it's possible that the number of transactions contained in block 890466 would have deviated from the average anyway, although not as markedly as in this case.
While the network continues to operate normally and mining of nearly empty blocks is not an immediate problem, the low transaction activity observed in recent days could be an indication that Bitcoin, at least temporarily, is being used more as a store of value than as a means of everyday exchange.
The block mined by Foundry USA, although small in number of transactions, is a reminder of the complexity and changing dynamics of the Bitcoin network. Some users believe this variability is healthy, as it follows normal cyclical supply and demand processes. Others see the absence of users participating in the Bitcoin network as a troubling sign for mining, making it increasingly dependent on a revenue source that will not always be available: the block subsidy.
